Hi,
Although I don't sell the BBB_DB25/26 any more I think it should be noted
that I have run MachineKit with limit/home switches on all three axes
(actually 4 since I had the Y and A axes slaved, and each had their own
limit/home switch). I'm not sure of your specific configuration, but the
board *will* work with switches.
Your are defeating the safety setup of the board by trying to use pin 1
as a different function. The board was design to work with both pin DB1
and pin DB10 working in conjunction as a safety stop loop in hardware.
There is a solution to using physical pin 1 in an alternative fashion.
First, you have to separate the output of the HCT541 pin 14 from the trace
on the board by lifting the leg of the IC off the board. Then you have to
route that *pin* (not board trace), to the input of DB10. This new route
(or wire) is now the safety circuity that would generally include a stop
switch. By completing that loop you complete the safety circuit as
designed, and the HAL program will still function as intended . After
lifting pin 14 of the HCT541 from the board, Pin 1 on the DB connector
will be basically floating. You can then wire any BBB output pin to the DB
pin and control DB1 noting that unless you provide it, there will be no
buffering of the BBB signal to the DB1 pin (i.e. the HCT541 can provide
more load than the BBB).
Jeff
On Sunday, May 20, 2018 at 2:46:14 PM UTC-7, John Dammeyer wrote:
>
>
>
> On Sunday, May 20, 2018 at 5:20:57 AM UTC-7, Eric wrote:
>>
>> That looks awesome!
>>
>> Are you going to be able to manually move the axes too, or is it now
>> going to be full CNC?
>>
>> At the speed that the XY axis turn the handles would have to be balanced
> and not near my private parts. That would hurt.
> The plan is full CNC. I have both a ShuttleXpress (on my MACH3 CNC
> router) and I'm trying out one of these on it since there's a windows
> driver for it.
> Ebay item # 221940342899
>
> So with that I can manually move the axis.
>
> But I've run into a problem with the BBB-DB25/26 and since Xylotex doesn't
> release schematics I'm not sure exactly how I'll fix it. Jeff did reply
> to a request about making the IOPWR# an active high output on pin 1 so it
> would enable the PMDX-126 BoB. But I've run into another issue and I'm not
> sure if it's the BBB MachineKit or the way the Cape is wired.
>
> I pulled my LinuxCNC PC off the shelf and connected the same Probotix
> BB-RF I was using with the Beagle. So LinuxCNC on a parallel port. A bit
> of mucking around to get the correct polarity signals for Machine Enable
> and ESTOP. At that point I can jog in the positive direction, pull the
> limit switch wire on the terminal strip to simulate running into a limit.
>
> At that point like the Beagle the Machine Power button on the screen goes
> off. The checkbox for override limits is not greyed out and I can check
> the box. Now I can click on the POWER button on the screen and jog in the
> negative direction and reconnect the limit switch input to ground. This is
> the one that is shared for all three axis. When I release the jog button
> The Override checkbox is greyed out again.
>
> The MachineKit with BBB cape doesn't do that. Hit a limit and Machine
> POWER button goes off. That also brings the IOPWR# low which then disables
> the entire set of level translation buffers. And the Override limits
> remains greyed out. So now clicking on the Machine POWER button doesn't do
> anything because the limit switch is still active.
>
> There may well be a solution but I haven't figured it out yet. At the
> moment I don't think the Xylotex cape will actually be usable with
> MachineKit that has limit switches.
>
>
--
website: http://www.machinekit.io blog: http://blog.machinekit.io github:
https://github.com/machinekit
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