Re: [Emc-users] Watchdog Sizing
On 4 December 2010 00:46, Kirk Wallace kwall...@wallacecompany.com wrote: I'm working on using an ATtiny to watch EMC2's charge pump. Why not use a charge pump circuit to watch the charge pump signal? That is what it was designed for, and is probably the most fail-safe solution. The timeout period is set by the capacitors and resistors you choose, and can't get accidentally changed or disabled. A charge pump circuit consists of two diodes, one small capacitor (a few hundred pF or a few nF), one medium capacitor (a few tens of nF), and a resistor. Also needed is something to look at its output and turn off the dangerous stuff if the output drops too low. That can be as simple as a transistor driving a relay coil, or you could use a schmidt trigger input logic gate followed by whatever you need to drive. No microcontroller, no programming, no configuration, no bits. Analog lives! John Kasunich -- John Kasunich jmkasun...@fastmail.fm -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
I was wondering, can a fault ever occur with EMC where the frequency of the charge pump frequency increases?? This would keep the charge pump detector 'up', but a uP would detect an error condition. Regards Roland On 8 December 2010 20:53, John Kasunich jmkasun...@fastmail.fm wrote: On 4 December 2010 00:46, Kirk Wallace kwall...@wallacecompany.com wrote: I'm working on using an ATtiny to watch EMC2's charge pump. Why not use a charge pump circuit to watch the charge pump signal? That is what it was designed for, and is probably the most fail-safe solution. The timeout period is set by the capacitors and resistors you choose, and can't get accidentally changed or disabled. A charge pump circuit consists of two diodes, one small capacitor (a few hundred pF or a few nF), one medium capacitor (a few tens of nF), and a resistor. Also needed is something to look at its output and turn off the dangerous stuff if the output drops too low. That can be as simple as a transistor driving a relay coil, or you could use a schmidt trigger input logic gate followed by whatever you need to drive. No microcontroller, no programming, no configuration, no bits. Analog lives! John Kasunich -- John Kasunich jmkasun...@fastmail.fm -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
actually - really? we could get it - just paying for your time? thanks sam On 12/8/2010 1:25 PM, Roland Jollivet wrote: I was wondering, can a fault ever occur with EMC where the frequency of the charge pump frequency increases?? This would keep the charge pump detector 'up', but a uP would detect an error condition. Regards Roland On 8 December 2010 20:53, John Kasunichjmkasun...@fastmail.fm wrote: On 4 December 2010 00:46, Kirk Wallacekwall...@wallacecompany.com wrote: I'm working on using an ATtiny to watch EMC2's charge pump. Why not use a charge pump circuit to watch the charge pump signal? That is what it was designed for, and is probably the most fail-safe solution. The timeout period is set by the capacitors and resistors you choose, and can't get accidentally changed or disabled. A charge pump circuit consists of two diodes, one small capacitor (a few hundred pF or a few nF), one medium capacitor (a few tens of nF), and a resistor. Also needed is something to look at its output and turn off the dangerous stuff if the output drops too low. That can be as simple as a transistor driving a relay coil, or you could use a schmidt trigger input logic gate followed by whatever you need to drive. No microcontroller, no programming, no configuration, no bits. Analog lives! John Kasunich -- John Kasunich jmkasun...@fastmail.fm -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
Roland Jollivet wrote: I was wondering, can a fault ever occur with EMC where the frequency of the charge pump frequency increases?? This would keep the charge pump detector 'up', but a uP would detect an error condition. It seems unlikely. The most likely effect of a software problem will be a crash. This would most likely cause pulses to stop, not to speed up. There is now a watchdog HAL component, which can monitor heartbeats from other modules (not that any other modules currently output such a heartbeat), and which will disable its output if any heartbeat stops. This would cause situations where some userspace modules die, but the realtime kernel keeps running, to still cause a fault. (As it is, if RT is running, the heartbeat will be output, regardless of whether e.g. the GUI has crashed) - Steve -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
S, Roland Jollivet piše: I was wondering, can a fault ever occur with EMC where the frequency of the charge pump frequency increases?? This would keep the charge pump detector 'up', but a uP would detect an error condition. Regards Roland NE567 can solve that too... -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Wed, 2010-12-08 at 13:53 -0500, John Kasunich wrote: On 4 December 2010 00:46, Kirk Wallace kwall...@wallacecompany.com wrote: I'm working on using an ATtiny to watch EMC2's charge pump. Why not use a charge pump circuit to watch the charge pump signal? That is what it was designed for, and is probably the most fail-safe solution. The timeout period is set by the capacitors and resistors you choose, and can't get accidentally changed or disabled. A charge pump circuit consists of two diodes, one small capacitor (a few hundred pF or a few nF), one medium capacitor (a few tens of nF), and a resistor. Also needed is something to look at its output and turn off the dangerous stuff if the output drops too low. That can be as simple as a transistor driving a relay coil, or you could use a schmidt trigger input logic gate followed by whatever you need to drive. This is what I have from the last time I played with the above type of circuit (sourced by JK?): http://www.wallacecompany.com/machine_shop/Shizuoka/watchdog-1b.png It worked on my breadboard but didn't work when I transferred it to a PCB. Other things came up and I didn't get back to fixing it. No microcontroller, no programming, no configuration, no bits. Analog lives! John Kasunich The analog method is probably more practical, but the digital solution may be viable too. It may be possible to do this with very few components (Vregulator, cap or two, ATtiny2313), at the same cost and have more flexibility (wide charge pump frequency range, learning mode, different fault responses, complex WD signal). I'm still playing with it, and for me the programming hurdle is pretty high, so who knows what the result might be. For someone needing a one-off circuit for a particular machine, the analog circuit above is probably the quickest solution. Especially, if there were(was?) a widget or cloud app that one could use to calculate the part values and model performance (Spice? but that is another unfilled time sink). -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Wed, 08 Dec 2010 12:15 -0800, Kirk Wallace kwall...@wallacecompany.com wrote: This is what I have from the last time I played with the above type of circuit (sourced by JK?): http://www.wallacecompany.com/machine_shop/Shizuoka/watchdog-1b.png It worked on my breadboard but didn't work when I transferred it to a PCB. Other things came up and I didn't get back to fixing it. A few things come to mind looking at that circuit. 1) Using a schmidt input gate (the 74LS14) is good, but I would use a CMOS input gate like a 74HC14. That way the loading on the pump can be ignored, and you can use much larger resistors and smaller caps. 2) The caps seem very large. When I see microfarads, I think electro- lytics, which have sloppy tolerances, high leakage current, and are polarized. This is the kind of circuit that wants to use film or ceramic caps. I would design it with the output cap (C3) as 0.1uF or maybe 1uF if I had that value laying around in ceramic or film. 3) The pump caps (C1 and C2) should be 10 to 100 times smaller than the output cap. You don't want a single pulse on the input to be able to transfer a significant amount of charge to the output - it should take many pulses to charge the output. 4) The time constant of the load resistor (R5) and the output cap (C3) is what determines how long it will take to drop out after the input stops pulsing. It should be much longer than the input period, but short enough to be safe. For a 1kHz input, I'd probably aim for 100mS. With a 0.1uF output cap, that is a 1 meg R5... hence the desire for a CMOS input. 5) I worry a bit about the extra stage. The classic charge pump circuit has only two diodes and one pump cap. Imagine the circuit as drawn, with IC1C and C2 removed, and D3 shorted. That version produces an output voltage that is always a little less than the output swing of IC1F minus two diode drops, which ensures that the input to IC1A is always lower than it's power supply rail. The version shown, with three diodes and two pump caps, can produce an output that approaches twice the IC1 output swing minus three diode drops. That exceeds the input rating of IC1A. The above statements are based on CMOS logic, where output swings are nearly rail-to-rail, and inputs are high impedance. With the LS family logic, you probably get a lot less output but the circuit is much harder to analyze in detail. The analog method is probably more practical, but the digital solution may be viable too. Of course there are many ways to solve the problem. It may be possible to do this with very few components (Vregulator, cap or two, ATtiny2313), at the same cost and have more flexibility (wide charge pump frequency range, learning mode, different fault responses, complex WD signal). The parts count may be similar, but the complexity is not. All of those features add complexity. The more complex something is, the more likely it is to contain un-anticipated failure modes, or just plain outright bugs. ANY software or firmware dramatically increases the complexity. I'm still playing with it, and for me the programming hurdle is pretty high, so who knows what the result might be. For someone needing a one-off circuit for a particular machine, the analog circuit above is probably the quickest solution. Especially, if there were(was?) a widget or cloud app that one could use to calculate the part values and model performance (Spice? but that is another unfilled time sink). It isn't that complicated. A 0.1uF output cap (C3) will work for the frequencies and delays we are interested in with EMC. Choose the output time constant and pick the R5 accordingly: R5 = T / C3. The pump cap(s) C1 (and C2, if using the two stage design) should be no more than 1/10 of C3, so 0.01uF (10nF) maximum. If you make them too small, you won't get enough output voltage. I'd probably start with 1nF, and increase if needed. The higher the charge pump frequency in relation to the output time constant, the smaller the pump caps can be. If you are pumping at 1kHz and the output time constant is 100mS, 1nF might be too small. If pumping at 10kHz, it should work fine. I guess in the end it depends on what you are familiar with. I can design the analog circuit in a few minutes, build a perfboard version in 20 minutes, and test it within an hour of starting. It would take me several times that long to get a microcontroller development system running to the point of being able to write and execute even the simplest program. Other people probably have the exact opposite situation. John -- John Kasunich jmkasun...@fastmail.fm -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net
Re: [Emc-users] Watchdog Sizing
On Wed, 2010-12-08 at 15:53 -0500, John Kasunich wrote: ... snip It isn't that complicated. A 0.1uF output cap (C3) will work for the frequencies and delays we are interested in with EMC. Choose the output time constant and pick the R5 accordingly: R5 = T / C3. ... snip Thank you John. I really appreciate the time you take to help. Using your information above, I redrew the schematic, which I'll revise as I go. It's at the bottom of the page here: http://www.wallacecompany.com/machine_shop/Shizuoka/ -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Wed, Dec 08, 2010 at 07:00:27PM -0800, Kirk Wallace wrote: Thank you John. I really appreciate the time you take to help. Using your information above, I redrew the schematic, which I'll revise as I go. It's at the bottom of the page here: http://www.wallacecompany.com/machine_shop/Shizuoka/ Kirk, apropos the comment there that it's not quite clear how the charge pump works, does it help at all, just for a more physical visualisation, to imagine C1 as a liquid pump's cylinder, with the top plate being the piston, driven up and down by IC1A, and D1 D2 as fluid non-return valves? C2 is the reservoir into which this pump is pumping positive charge [1]. If C1 isn't driven up and down, charge isn't going to flow out of ground to C2, and its charge decays through R2. The only change I'd make to the circuit is to connect R1 to +5v, so that the default state of IC1A output is low. That is because a capacitor is more likely than not to go short circuit in the rare event that it fails. That would give a false OK, in the absence of input. (It'll work fine as-is if there's no component failure.) Dunno if my attempt to paint a picture really ended up less laboured, and more descriptive that going through it in purely electronic terms, but we can always do that if this attempt isn't as clear as it should be. Erik [1] While it's electrons going the other way really, it's more convenient to discuss positive charge when talking about accumulating a positive voltage. -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
S, Erik Christiansen piše: On Wed, Dec 08, 2010 at 07:00:27PM -0800, Kirk Wallace wrote: Thank you John. I really appreciate the time you take to help. Using your information above, I redrew the schematic, which I'll revise as I go. It's at the bottom of the page here: http://www.wallacecompany.com/machine_shop/Shizuoka/ Kirk, apropos the comment there that it's not quite clear how the charge pump works, does it help at all, just for a more physical visualisation, to imagine C1 as a liquid pump's cylinder, with the top plate being the piston, driven up and down by IC1A, and D1 D2 as fluid non-return valves? C2 is the reservoir into which this pump is pumping positive charge [1]. If C1 isn't driven up and down, charge isn't going to flow out of ground to C2, and its charge decays through R2. The only change I'd make to the circuit is to connect R1 to +5v, so that the default state of IC1A output is low. That is because a capacitor is more likely than not to go short circuit in the rare event that it fails. That would give a false OK, in the absence of input. (It'll work fine as-is if there's no component failure.) Dunno if my attempt to paint a picture really ended up less laboured, and more descriptive that going through it in purely electronic terms, but we can always do that if this attempt isn't as clear as it should be. Erik Maybe you have just too little current in output. So just route unused gates paralel to last one. (pins 1,3,5,9 together and pins 2,4,6,8 together) -- This SF Dev2Dev email is sponsored by: WikiLeaks The End of the Free Internet http://p.sf.net/sfu/therealnews-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
If the pulse from EMC or any other program is consistent, then your circuit only needs one little tactile switch. If you press this switch, the micro will go into learn mode and time the interval between pulses from EMC. If can now add a +/- 10% or whatever margin and flag the alarm outside that. Regards Roland On 4 December 2010 00:46, Kirk Wallace kwall...@wallacecompany.com wrote: I'm working on using an ATtiny to watch EMC2's charge pump. The plan is to have a count down that gets reset by a charge pump edge. If the counter reaches 0, then an alarm pin gets set. The counter reset value determines how long the charge pump has to do a reset. I can write code with the appropriate value, but if I wanted to make the watchdog watcher generic, I should have a way for a user to make the setting on the fly. My problem is that I can do this with a dip switch, potentiometer, serial or SPI link, or some other way I haven't thought of yet. Does anyone have any thoughts on what would be a good way to do this? The primary purpose for the watcher is to keep the motor drivers powered down until the PC boots and EMC2 is running. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- Oracle to DB2 Conversion Guide: New IBM DB2 features make compatibility easy. Learn about native support for PL/SQL, new data types, scalar functions, improved concurrency, built-in packages, OCI, SQL*Plus, data movement tools, best practices and more - all designed to run applications on both DB2 and Oracle platforms. http://p.sf.net/sfu/oracle-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
S, Erik Christiansen piše: On Sat, Dec 04, 2010 at 09:04:54AM -0800, Kirk Wallace wrote: Then I got to thinking about what Slavko mentioned previously, about this is a safety device and I should think in terms of how it could fail. So long as the microcontroller's on-board watchdog is enabled, you have a watchdog watchdog to provide recovery from a soft error. When driving a critical output, you can add a pull-[up|down] resistor, to maintain the desired default state during power-up and any reset applied by the on-board watchdog. Erik That's funn... If you already have watchdog (hardware) to keep ATtiny RESET good why do you need that MCU at all?!? Seems nonsense for me. I don't hate MCU's. I use it a lot. But in places where they (I think) are needed. And Watchdog of that kind is surely not good idea. But someone on forum say's something about PLL. That can be good idea too. There are some tondecoder PLL's like NE567. Cheap 8 pin DIL chip and two resistor's and one cap can solve that problem perfectly. You just need to do software chargepump at servo rate (1ms for example) and got 500Hz output for PLL. That's seems ideal too for me. Can't triger on wrong pulses and react fast. Slavko. -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Sun, 2010-12-05 at 09:44 +0200, Slavko Kocjancic wrote: ... snip That's funn... If you already have watchdog (hardware) to keep ATtiny RESET good why do you need that MCU at all?!? Seems nonsense for me. I think because the MCU is used to validate EMC2 before powering up the dangerous bits of the machine. The MCU's internal watchdog validates the MCU itself(?), which is a separate function. I need to read the MCU manual to see what features come with the using the watchdog. I suppose EMC2 could be used to validate the MCU, but things are getting complicated. I don't hate MCU's. I use it a lot. But in places where they (I think) are needed. And Watchdog of that kind is surely not good idea. But someone on forum say's something about PLL. That can be good idea too. There are some tondecoder PLL's like NE567. Cheap 8 pin DIL chip and two resistor's and one cap can solve that problem perfectly. You just need to do software chargepump at servo rate (1ms for example) and got 500Hz output for PLL. That's seems ideal too for me. Can't triger on wrong pulses and react fast. Slavko. The reason I am leaning toward the ATtiny is that I have a guess in how to make it work and the parts cost and count is the same or less than other methods I've looked at. Most methods have merit. If I take the time to learn how an NE567 works (likely), I may go with that. It would save me having to figure out the software. Ideally, I suppose I should build and test a few different designs, which would most likely result in more changes. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Sun, Dec 05, 2010 at 01:40:58AM -0800, Kirk Wallace wrote: On Sun, 2010-12-05 at 09:44 +0200, Slavko Kocjancic wrote: ... snip That's funn... If you already have watchdog (hardware) to keep ATtiny RESET good why do you need that MCU at all?!? Seems nonsense for me. I think because the MCU is used to validate EMC2 before powering up the dangerous bits of the machine. The MCU's internal watchdog validates the MCU itself(?), which is a separate function. I need to read the MCU manual to see what features come with the using the watchdog. I suppose EMC2 could be used to validate the MCU, but things are getting complicated. Hmmm, its seems Slavko read right past microcontroller's on-board watchdog in my post. :-) Yes, the ATtiny's watchdog is on-chip, so the quandary doesn't arise. I wouldn't trust a microcontroller in any critical role, without a hardware supervisor. On an AVR, it has it's own clock, so even if the CPU clock dies, the watchdog reset will tri-state port pins. That is why a pull-[up|down] to a safe state is helpful on a port pin. It takes over in reset scenarios. The watchdog improves the reliability of the microcontroller by providing recovery from soft errors, whether caused by extreme transients or alpha particles. However, the ATtiny's watchdog is best enabled only after its program has been debugged. ;-) Erik -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
S, Erik Christiansen piše: On Sun, Dec 05, 2010 at 01:40:58AM -0800, Kirk Wallace wrote: On Sun, 2010-12-05 at 09:44 +0200, Slavko Kocjancic wrote: ... snip That's funn... If you already have watchdog (hardware) to keep ATtiny RESET good why do you need that MCU at all?!? Seems nonsense for me. I think because the MCU is used to validate EMC2 before powering up the dangerous bits of the machine. The MCU's internal watchdog validates the MCU itself(?), which is a separate function. I need to read the MCU manual to see what features come with the using the watchdog. I suppose EMC2 could be used to validate the MCU, but things are getting complicated. Hmmm, its seems Slavko read right past microcontroller's on-board watchdog in my post. :-) Yes, the ATtiny's watchdog is on-chip, so the quandary doesn't arise. I wouldn't trust a microcontroller in any critical role, without a hardware supervisor. On an AVR, it has it's own clock, so even if the CPU clock dies, the watchdog reset will tri-state port pins. That is why a pull-[up|down] to a safe state is helpful on a port pin. It takes over in reset scenarios. The watchdog improves the reliability of the microcontroller by providing recovery from soft errors, whether caused by extreme transients or alpha particles. However, the ATtiny's watchdog is best enabled only after its program has been debugged. ;-) Erik I use that MCU's And can tell you that Watchdog on tiny controlers are good one. But have problems. The mcu itself MUST be started correctly (reseted) and after that watchdog work correctly. But when big machine starts (with a lot of solenoids) the proper reset is wery hard to realize! And belive me that if you think in a way that unproper reset may casuse injury then just stay off that. Slavko. -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
Just my 2 cents... For watchdog thing I think the ATtiny is just overkill. That kind of operation can be done with simple 555 timer or even few diodes and transistor. Don't get me wrong. The ATtiny (15L) for example can do that job but as safety device the any micro isn't good way. And if system hang who says that it can't set wrong configuration and disable watchdog? Just do that without micro and use micro for other complicated thing.. 2010/12/4 Kirk Wallace kwall...@wallacecompany.com On Sat, 2010-12-04 at 09:55 +0800, Jim Coleman wrote: I like the idea of a dip switch or solder bridges if one doesn't plan on changing the setting alot and wants to save the cost of the dip switch. while the pot would be easy to adjust, it's less precise than a truth table of the dip/bridge positions and the resultant reset timer. Jim Thanks Jim. I agree that it would be nice to have a precise, stable input, but I am also trying to avoid any hardware complexity in order to avoid an upgrade loop (ATtiny - ATmega - Atom Cube - Nanotube Superconducting Buckyball hyper... ). It may also be that one or a few presets might be enough. If charge pump is running at 1kHz (based on servo thread), it may be acceptable to wait up to a hundred cycles or .1 seconds to trip an e-stop. If this is the case, .1 seconds might cover the range of common watchdog frequencies. Without testing or experience, I have a hard time knowing what will work. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Fri, Dec 03, 2010 at 07:54:57PM -0800, Kirk Wallace wrote: I really had no idea if the memory would be enough. I would have worked on it until I went blind in one eye. Oh, it's enough for what you want to do now. But ISTR a home switch + index filter, on the other thread. It can do that too, if pins can be found. But then there's the extra functionality we just have to have, when we're nearly finished. ;-) In looking for something else (small h-bridge) I found this (and ordered): http://www.sparkfun.com/products/9147 There is even some code to use as a reference: http://www.sparkfun.com/Code/AVR-Stick_v12.zip Ah, they use the USB frame timing to calibrate the on-board RC oscillator. I saw USB transmit code, but nothing for receive (i.e. for setting watchdog timing.) Ah, your last site has projects involving USB output. http://www.obdev.at/products/vusb/projects.html The small H-bridge design I spotted there is another very low power example, using the L293D. I'd at the very least put some DPAK FETs on a PCB, instead. I'm not sure I'd trust the shoot-through provisions of one of those amateur designs. If not using half-bridge drivers with dead-time, the ATtiny26's timer1 has complementary outputs with dead-time fixed at one prescaler clock interval. However, if you want to do motor PID, then a reasonable swag of the 1k instruction space is eaten. Incidentally, the ATmega8 (used the same design) is old. The ATmega48 is a scalable replacement. I feel a project cascade coming on. The trouble escalates when you succumb do doing just one more design, with just one more layout to economise on the shipping from the cheap PCB places in Asia. :-) Erik -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
I would use a single pin for communication to the host with some variant of the one-wire protocol used by iButtons. It is simple, elegant, and relatively insensitive to timing. Ken On 12/04/2010 04:30 AM, Erik Christiansen wrote: On Fri, Dec 03, 2010 at 07:54:57PM -0800, Kirk Wallace wrote: I really had no idea if the memory would be enough. I would have worked on it until I went blind in one eye. Oh, it's enough for what you want to do now. But ISTR a home switch + index filter, on the other thread. It can do that too, if pins can be found. But then there's the extra functionality we just have to have, when we're nearly finished. ;-) In looking for something else (small h-bridge) I found this (and ordered): http://www.sparkfun.com/products/9147 There is even some code to use as a reference: http://www.sparkfun.com/Code/AVR-Stick_v12.zip Ah, they use the USB frame timing to calibrate the on-board RC oscillator. I saw USB transmit code, but nothing for receive (i.e. for setting watchdog timing.) Ah, your last site has projects involving USB output. http://www.obdev.at/products/vusb/projects.html The small H-bridge design I spotted there is another very low power example, using the L293D. I'd at the very least put some DPAK FETs on a PCB, instead. I'm not sure I'd trust the shoot-through provisions of one of those amateur designs. If not using half-bridge drivers with dead-time, the ATtiny26's timer1 has complementary outputs with dead-time fixed at one prescaler clock interval. However, if you want to do motor PID, then a reasonable swag of the 1k instruction space is eaten. Incidentally, the ATmega8 (used the same design) is old. The ATmega48 is a scalable replacement. I feel a project cascade coming on. The trouble escalates when you succumb do doing just one more design, with just one more layout to economise on the shipping from the cheap PCB places in Asia. :-) Erik -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Sat, 2010-12-04 at 20:30 +1100, Erik Christiansen wrote: ... snip Oh, it's enough for what you want to do now. But ISTR a home switch + index filter, on the other thread. It can do that too, if pins can be found. But then there's the extra functionality we just have to have, when we're nearly finished. ;-) I just want to do the watchdog on the AVR. I believe EMC2 should do as many functions as possible. The AVR should do what ever the PC can't, such as check PC/EMC2 function. There may be other things too, such as motion control for tool changers, but I see this more as an EMC2 feature that is missing. ... snip Ah, they use the USB frame timing to calibrate the on-board RC oscillator. I saw USB transmit code, but nothing for receive (i.e. for setting watchdog timing.) Ah, your last site has projects involving USB output. http://www.obdev.at/products/vusb/projects.html This is something I need to look into. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Sat, 2010-12-04 at 09:16 -0500, Kenneth Lerman wrote: I would use a single pin for communication to the host with some variant of the one-wire protocol used by iButtons. It is simple, elegant, and relatively insensitive to timing. Ken USB is attractive because I can get a cheap AVR board with firmware that could work on any PC with terminal software (minicom or putty). All that I am currently looking for is a one time setting of one parameter value, but the more I think about it, I may only need one of a few presets which could be handled by two pins and a dip switch, or a trim pot. I have used SPI for a DAC, but I had to bit-bang it through the parport and it would only work with my HAL component, which is fine for the particular application. One problem is that I made an assumption that I needed to catch the first late edge of the charge pump, and to be more generic, I needed to finely tune the countdown value to match whatever charge pump frequency might be used. If I change the requirement to catching the loss of the charge pump signal within a reasonable time, the parameter tuning goes away. Then I got to thinking about what Slavko mentioned previously, about this is a safety device and I should think in terms of how it could fail. Changing track, again, the charge pump signal may not be the best thing to use, because all it would take is noise on the line to mimic the pump. I think I should make some sort of data pump component, such as send out a byte every servo period, then have the watchdog watcher check for the proper byte. This changes the form of the link between EMC2 and the watcher, and maybe the parameter setting requirements, or lack thereof. This reminds me of a previous project I was considering, but forgot about, which is to use a data stream to fail-safe limit switches. I have more thinking to do, carry on. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
Changing track, again, the charge pump signal may not be the best thing to use, because all it would take is noise on the line to mimic the pump. I think I should make some sort of data pump component, such as send out a byte every servo period, then have the watchdog watcher check for the proper byte. This changes the form of the link between EMC2 and the watcher, and maybe the parameter setting requirements, or lack thereof. This reminds me of a previous project I was considering, but forgot about, which is to use a data stream to fail-safe limit switches. I have more thinking to do, carry on. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA Maybe a simple watchdog that avoids the noise trigger issue would be a DPLL that locks onto the chargepump signal. Once locked it enables its output and stops rate tracking. Any subsequent variation in rate (beyond some margin) would trigger a watchdog bite. If run from the servo loop this rate tolerance could be quite small so at 1 mS servo thread, the watchdog could bite at 1.1 ms(and .9 mS). This also does not require any watchdog timeout setting jumpers etc. -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Sat, 2010-12-04 at 09:38 -0800, Peter C. Wallace wrote: ... snip Maybe a simple watchdog that avoids the noise trigger issue would be a DPLL that locks onto the chargepump signal. Once locked it enables its output and stops rate tracking. Any subsequent variation in rate (beyond some margin) would trigger a watchdog bite. If run from the servo loop this rate tolerance could be quite small so at 1 mS servo thread, the watchdog could bite at 1.1 ms(and .9 mS). This also does not require any watchdog timeout setting jumpers etc. Brilliant. I could have the ATtiny sample the pump to get a short edge count and a long edge count, add a cushion, then switch to survey mode to check that the edges are within the two counts (within an error rate?). Seems kind of simple now. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Sat, Dec 04, 2010 at 09:04:54AM -0800, Kirk Wallace wrote: Then I got to thinking about what Slavko mentioned previously, about this is a safety device and I should think in terms of how it could fail. So long as the microcontroller's on-board watchdog is enabled, you have a watchdog watchdog to provide recovery from a soft error. When driving a critical output, you can add a pull-[up|down] resistor, to maintain the desired default state during power-up and any reset applied by the on-board watchdog. Erik -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Watchdog Sizing
I'm working on using an ATtiny to watch EMC2's charge pump. The plan is to have a count down that gets reset by a charge pump edge. If the counter reaches 0, then an alarm pin gets set. The counter reset value determines how long the charge pump has to do a reset. I can write code with the appropriate value, but if I wanted to make the watchdog watcher generic, I should have a way for a user to make the setting on the fly. My problem is that I can do this with a dip switch, potentiometer, serial or SPI link, or some other way I haven't thought of yet. Does anyone have any thoughts on what would be a good way to do this? The primary purpose for the watcher is to keep the motor drivers powered down until the PC boots and EMC2 is running. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- Oracle to DB2 Conversion Guide: New IBM DB2 features make compatibility easy. Learn about native support for PL/SQL, new data types, scalar functions, improved concurrency, built-in packages, OCI, SQL*Plus, data movement tools, best practices and more - all designed to run applications on both DB2 and Oracle platforms. http://p.sf.net/sfu/oracle-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Fri, Dec 03, 2010 at 02:46:16PM -0800, Kirk Wallace wrote: I'm working on using an ATtiny to watch EMC2's charge pump. The plan is to have a count down that gets reset by a charge pump edge. If the counter reaches 0, then an alarm pin gets set. The counter reset value determines how long the charge pump has to do a reset. I can write code with the appropriate value, but if I wanted to make the watchdog watcher generic, I should have a way for a user to make the setting on the fly. My problem is that I can do this with a dip switch, potentiometer, serial or SPI link, or some other way I haven't thought of yet. Does anyone have any thoughts on what would be a good way to do this? The primary purpose for the watcher is to keep the motor drivers powered down until the PC boots and EMC2 is running. That is an admirable way to design, Kirk. Here are a few thoughts, which probably don't do more than explore what you're already thinking. If the device is 14 pin, then a dip switch is feasible, but still eats pins which would be needed for any ancilliary functions which arise later in the project. On an 8 pin device, another solution is needed, if a broad range of timings is to be achieved. Yes, a potentiometer connected to an A/D uses only one pin. Even if the A/D is only good to 8 or 9 of the 10 bits, after accounting for errors, then it's better than 0.4%. Even if the user didn't want a trimpot (potentially in an environment with metallic particles and coolant mist) affecting reliability, he could solder in two fixed resistors instead. (And a filter capacitor on the junction, to reduce any noise injected from power circuits. If the parallel combination of the two resistors is over 10k, the capacitor also helps compensate for the small current drawn by the A/D's S/H capacitance during sampling.) Alternatively, if sufficient code space remains, to handle user interfacing, then we the EEPROM could be used, as you're considering with the serial solutions. If we drive a LED, via a transistor, there's negligible load on the port pin, with a base resistor of several kOhm, so we also connect a NO pushbutton switch to ground. Now, firmware sets the port as input, after reset/power_up. If the button is pressed at power_up, we go into SET mode, and await release of the button. Once there, we switch the port pin to output, and blink the LED once, then again switch to input, and wait 1-2 seconds for the button to be pressed. In the absence of input, we repeat with another blink. When there finally is input, we read a software counter we've incremented between blinks, and take it as a direct value (e.g. ms x 20) or an index into a short table, if so wide a range of values is needed, that waiting for incrementing LED blink counts would become tedious. An enhancement of this could be to first issue long blinks, signifying tens of timing units, and capture N of them with a button push after the Nth blink, then repeat with shorter blinks, signifying that we now want the units, M, such that the whole value = 10*N + M. That more conveniently covers a broader range of values, but still with a fine resolution, than linear counting. OK, that's fiddlier than a potentiometer, but there are compensations. The LED may be used for other indications after set-up, and the pushbutton is also available for other user input. Then there's your serial solutions. Since all users have the EMC2 host to hand, and probably have a serial port, even if by means of a USB/serial dongle, then minicom or ckermit could easily be used to input a value. The input could be echoed, to confirm that it was correctly received. But that would use a second port pin. If we stay on an ATtiny, then we need code space for a software UART. (I haven't checked that an ATtiny's uncalibrated RC oscillator will always be accurate enough for serial communication, but the first character sent from the PC could be used for auto-calibration.) Once a serial link to the EMC2 host exists, is it possible to resist the temptation to put in a $3 - $4 ATmega, to limit the risk of running out of code space, once the ancilliary functions stick their grinning faces over the parapet? Hmm, what other solutions are there? Erik -- For humans, honesty is a matter of degree. Engineers are always honest in matters of technology and human relationships. That's why it's a good idea to keep engineers away from customers, romantic interests, and other people who can't handle the truth. (Scott Adams - The Dilbert principle) -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more.
Re: [Emc-users] Watchdog Sizing
I like the idea of a dip switch or solder bridges if one doesn't plan on changing the setting alot and wants to save the cost of the dip switch. while the pot would be easy to adjust, it's less precise than a truth table of the dip/bridge positions and the resultant reset timer. Jim On Sat, Dec 4, 2010 at 6:46 AM, Kirk Wallace kwall...@wallacecompany.comwrote: I'm working on using an ATtiny to watch EMC2's charge pump. The plan is to have a count down that gets reset by a charge pump edge. If the counter reaches 0, then an alarm pin gets set. The counter reset value determines how long the charge pump has to do a reset. I can write code with the appropriate value, but if I wanted to make the watchdog watcher generic, I should have a way for a user to make the setting on the fly. My problem is that I can do this with a dip switch, potentiometer, serial or SPI link, or some other way I haven't thought of yet. Does anyone have any thoughts on what would be a good way to do this? The primary purpose for the watcher is to keep the motor drivers powered down until the PC boots and EMC2 is running. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- Oracle to DB2 Conversion Guide: New IBM DB2 features make compatibility easy. Learn about native support for PL/SQL, new data types, scalar functions, improved concurrency, built-in packages, OCI, SQL*Plus, data movement tools, best practices and more - all designed to run applications on both DB2 and Oracle platforms. http://p.sf.net/sfu/oracle-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Sat, 2010-12-04 at 12:50 +1100, Erik Christiansen wrote: ... snip Once a serial link to the EMC2 host exists, is it possible to resist the temptation to put in a $3 - $4 ATmega, to limit the risk of running out of code space, once the ancilliary functions stick their grinning faces over the parapet? Thanks for your reply Erik. But shucks, if we're thinking about going to an ATmega ... http://www.handlewithlinux.com/smallest-linux-pc http://www.shimafuji.co.jp/product/semc5701a01.html -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Fri, Dec 03, 2010 at 06:12:52PM -0800, Kirk Wallace wrote: But shucks, if we're thinking about going to an ATmega ... http://www.handlewithlinux.com/smallest-linux-pc http://www.shimafuji.co.jp/product/semc5701a01.html Mega-Kewl! (I want a black one, ... anna yellow one. :-) Seriously though, starting with an ATtiny, then running out of code space is _so_ frustrating. Thinking as a hardware designer, it's fair to say A little 'un will do the job, but the benefit of doing it in firmware is in having design headroom, through adequate codespace. I'm pretty sure that if I did one with the serial link, I couldn't stop myself from adding stuff till an ATmega would be good to have. Oh -oh, checking a datasheet, I am though forced to admit that the ATtiny25 could be substituted with a 45 or even an 85, for 8 kB codespace (4000 instructions). That further forces me to admit that I'm having trouble resisting thoughts of what else could be stuffed into a nifty little programmable extension of the EMC2 host. You're right. An ATtiny is more than adequate, even if(BS)(BS) when we get carried away. (At least in moderation) Erik -- Most of us, when all is said and done, like what we like and make up reasons for it afterwards. -- Søren F. Petersen -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Watchdog Sizing
On Sat, 2010-12-04 at 09:55 +0800, Jim Coleman wrote: I like the idea of a dip switch or solder bridges if one doesn't plan on changing the setting alot and wants to save the cost of the dip switch. while the pot would be easy to adjust, it's less precise than a truth table of the dip/bridge positions and the resultant reset timer. Jim Thanks Jim. I agree that it would be nice to have a precise, stable input, but I am also trying to avoid any hardware complexity in order to avoid an upgrade loop (ATtiny - ATmega - Atom Cube - Nanotube Superconducting Buckyball hyper... ). It may also be that one or a few presets might be enough. If charge pump is running at 1kHz (based on servo thread), it may be acceptable to wait up to a hundred cycles or .1 seconds to trip an e-stop. If this is the case, .1 seconds might cover the range of common watchdog frequencies. Without testing or experience, I have a hard time knowing what will work. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
