Re: [Emc-users] Encoder as MPG over serial?
Thanks Colin. Your suggestions on how to proceed will be a useful roadmap for me. You might be interested in this to save pins on the Arduino: http://www.web4robot.com/SerialLCD.html. . I haven't seen a better price for such a unit and the others don't support the additional inputs. Best regards, Greg From: Colin Kingsbury ckingsb...@gmail.com To: emc-users@lists.sourceforge.net Sent: Thu, September 30, 2010 11:58:02 AM Subject: Re: [Emc-users] Encoder as MPG over serial? I'm starting up a blog at http://ckcnc.wordpress.com to document what I'm working on. There's nothing much there yet but there will be more over the next couple weeks. I've got all the pieces working, what I need to do know is tighten everything up. I'm designing a board that will have two encoders (MPG and Spindle/FRO) and switches for axis and scale selection, continuous feed, and cycle start/pause/single block, plus maybe a few extra depending on what I can squeeze in. What I'm playing with right now is adding an LCD display that could act as a remote DRO, which would be really nice to have on a pendant. It's tempting because a 20x4 display can convey a ton of information with 6 output pins from the Arduino. But, I am running tight on pins as it is, and I feel like I'd prefer to have hard LEDs for things like the axis and scale selections, rather than forcing people to read an LCD. Of course, a Max7219 -segment LED driver gives me 64 outputs from 3 pins, so maybe if I can get both to work more power! But I'm also unsure about how much data I can reliably push through the wire. I can do all the core stuff with single-byte messages very easily, but a DRO message requires 7 for a value like X12.345 (using ASCII), and it gets messier if your messages have different lengths. So I'm just not sure how far I am from running into contentions between, say, HAL pushing position updates to the DRO, and the MPG wanting to move the axis. In principle there's plenty of bandwidth at slightly higher speeds like 19200 or 57600bps, but my sense is these can be sufficiently less reliable that I'd prefer to be really conservative, especially if I start selling the board. Anyway, for your hacking in the meantime, my main suggestion is to build the stack up in stages like this: - Write your Arduino sketch with one or two inputs and outputs. Test it with the serial monitor until it's doing exactly what you think it should. - Write a minimal Python program you can run from the command line, and make it talk to the Arduino, again using the serial monitor to verify everything. - Add the HAL component to the Python program, and test it from the command line with halrun to verify it's setting pin values as you expect. - THEN, and only then, link it up with your GUI of choice. Basically, my experience was that the vast majority of my problems were actually in getting Python and the Arduino to communicate as I wanted. Getting Python to communicate with HAL was almost trivial. Colin- Your post was quite timely for me as I just recieved an Arduino with the intention of creating exactly the same setup for my gantry router. If you could share your code it would be a tremendous help and quite possibly save me from having my head explode. :) -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Encoder as MPG over serial?
I'm starting up a blog at http://ckcnc.wordpress.com to document what I'm working on. There's nothing much there yet but there will be more over the next couple weeks. I've got all the pieces working, what I need to do know is tighten everything up. I'm designing a board that will have two encoders (MPG and Spindle/FRO) and switches for axis and scale selection, continuous feed, and cycle start/pause/single block, plus maybe a few extra depending on what I can squeeze in. What I'm playing with right now is adding an LCD display that could act as a remote DRO, which would be really nice to have on a pendant. It's tempting because a 20x4 display can convey a ton of information with 6 output pins from the Arduino. But, I am running tight on pins as it is, and I feel like I'd prefer to have hard LEDs for things like the axis and scale selections, rather than forcing people to read an LCD. Of course, a Max7219 -segment LED driver gives me 64 outputs from 3 pins, so maybe if I can get both to work more power! But I'm also unsure about how much data I can reliably push through the wire. I can do all the core stuff with single-byte messages very easily, but a DRO message requires 7 for a value like X12.345 (using ASCII), and it gets messier if your messages have different lengths. So I'm just not sure how far I am from running into contentions between, say, HAL pushing position updates to the DRO, and the MPG wanting to move the axis. In principle there's plenty of bandwidth at slightly higher speeds like 19200 or 57600bps, but my sense is these can be sufficiently less reliable that I'd prefer to be really conservative, especially if I start selling the board. Anyway, for your hacking in the meantime, my main suggestion is to build the stack up in stages like this: - Write your Arduino sketch with one or two inputs and outputs. Test it with the serial monitor until it's doing exactly what you think it should. - Write a minimal Python program you can run from the command line, and make it talk to the Arduino, again using the serial monitor to verify everything. - Add the HAL component to the Python program, and test it from the command line with halrun to verify it's setting pin values as you expect. - THEN, and only then, link it up with your GUI of choice. Basically, my experience was that the vast majority of my problems were actually in getting Python and the Arduino to communicate as I wanted. Getting Python to communicate with HAL was almost trivial. Colin- Your post was quite timely for me as I just recieved an Arduino with the intention of creating exactly the same setup for my gantry router. If you could share your code it would be a tremendous help and quite possibly save me from having my head explode. :) -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Encoder as MPG over serial?
For anyone who was curious, I figured this out last night and it turned out to be a lot easier than I thought. Basically, all I needed to do was use the MPG howto from the wiki ( http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Hooking_Up_A_MPG_Pendant), and instead of mapping the encoder inputs to the parallel port pins, I created a phaseA and phaseB pin in my Python HAL component, and mapped to those. For once, everything actually worked on the first try. I did notice one small error on the wiki page, which was the omission of 'setp' in the calls to set axis.N.jog-vel-mode. I edited the page to add this. On Tue, Sep 28, 2010 at 1:14 PM, Colin Kingsbury ckingsb...@gmail.comwrote: So, thanks to an assist from Jeff Epler and Chris Radek, I've gotten my Arduino-HAL interface more or less fully functional with both inputs and outputs. My purpose for this is to build a human-machine interface (read: control panel for my mill). So far I've gotten it to turn input pins in HALUI on and off, and turn external LEDs on and off based on the status of output pins. What I'm wondering about is how best to work an encoder into this. Currently, the way I'm doing it is to have the arduino read the encoder outputs and convert them to a signal which represents one pulse in the CW or CCW direction. The Python script receives the signal, and then jogs the appropriate axis in the + or - direction for 1/10th of a second. So far, the motion seems smooth (on screen, I haven't tried it on one of my machines yet), but I'm wondering if there's a better way. The catch is that I'd like to keep this on the serial connection, both to save the parallel port pins, and also for the elegance of being able to do everything over the Arduino's USB cable. -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Encoder as MPG over serial?
Colin- Your post was quite timely for me as I just recieved an Arduino with the intention of creating exactly the same setup for my gantry router. If you could share your code it would be a tremendous help and quite possibly save me from having my head explode. :) Thanks, Greg From: Colin Kingsbury ckingsb...@gmail.com To: emc-users@lists.sourceforge.net Sent: Wed, September 29, 2010 11:12:22 AM Subject: Re: [Emc-users] Encoder as MPG over serial? For anyone who was curious, I figured this out last night and it turned out to be a lot easier than I thought. Basically, all I needed to do was use the MPG howto from the wiki ( http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Hooking_Up_A_MPG_Pendant), and instead of mapping the encoder inputs to the parallel port pins, I created a phaseA and phaseB pin in my Python HAL component, and mapped to those. For once, everything actually worked on the first try. I did notice one small error on the wiki page, which was the omission of 'setp' in the calls to set axis.N.jog-vel-mode. I edited the page to add this. On Tue, Sep 28, 2010 at 1:14 PM, Colin Kingsbury ckingsb...@gmail.comwrote: So, thanks to an assist from Jeff Epler and Chris Radek, I've gotten my Arduino-HAL interface more or less fully functional with both inputs and outputs. My purpose for this is to build a human-machine interface (read: control panel for my mill). So far I've gotten it to turn input pins in HALUI on and off, and turn external LEDs on and off based on the status of output pins. What I'm wondering about is how best to work an encoder into this. Currently, the way I'm doing it is to have the arduino read the encoder outputs and convert them to a signal which represents one pulse in the CW or CCW direction. The Python script receives the signal, and then jogs the appropriate axis in the + or - direction for 1/10th of a second. So far, the motion seems smooth (on screen, I haven't tried it on one of my machines yet), but I'm wondering if there's a better way. The catch is that I'd like to keep this on the serial connection, both to save the parallel port pins, and also for the elegance of being able to do everything over the Arduino's USB cable. -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Encoder as MPG over serial?
So, thanks to an assist from Jeff Epler and Chris Radek, I've gotten my Arduino-HAL interface more or less fully functional with both inputs and outputs. My purpose for this is to build a human-machine interface (read: control panel for my mill). So far I've gotten it to turn input pins in HALUI on and off, and turn external LEDs on and off based on the status of output pins. What I'm wondering about is how best to work an encoder into this. Currently, the way I'm doing it is to have the arduino read the encoder outputs and convert them to a signal which represents one pulse in the CW or CCW direction. The Python script receives the signal, and then jogs the appropriate axis in the + or - direction for 1/10th of a second. So far, the motion seems smooth (on screen, I haven't tried it on one of my machines yet), but I'm wondering if there's a better way. The catch is that I'd like to keep this on the serial connection, both to save the parallel port pins, and also for the elegance of being able to do everything over the Arduino's USB cable. -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
