ColorCNC Colorlight 5A-75E/5A-75B as FPGA controller board

Without changing the buffers, you are limited to output only. For running steppers this is ideal as noted above. However, you are not limited to step/dir, although this is the most used system. When required you can also use up / down, or direct drive (i.e. Using a half-bridge).

Of you can share your setup, I'm more then willing to whip up a configuration and a manual how to proceed.

Hello.
If solder buffers for input can be used with H-bridge
for driving dc brushed servos with incremental encoder feedback ?
( pwm output / step-dir-quadrature output / encoder input / gpio )

What input buffer chips are needed and how to solder ? what modifications needed ?
example for 5A-75E v8 ?
(here does not have example for that version litex-cnc.readthedocs.io/en/latest/examples/index.html )

So do I Have to reconfig the original Lcnc.ini and Lcnc.hal file for this? Im a newbie in this situation. Does anybody have a configuration for step/dir for 3 axes? Or maybe somebody can tell what to do in the hal file?

juergenmoser wrote:

So do I Have to reconfig the original Lcnc.ini and Lcnc.hal file for this? Im a newbie in this situation. Does anybody have a configuration for step/dir for 3 axes? Or maybe somebody can tell what to do in the hal file?

 
Hi,
the files you are referring to are a configuration that Is already a 3 axes step+dir stepper configuration.
In that configuration the inputs are for reading stepper drivers alarm signal (Lcnc.00.input.03.in-n) and for the 3 endstops (Lcnc.00.input.00.in-n Lcnc.00.input.01.in-n Lcnc.00.input.02.in-n) used for homing the 3 axes.
With a board not modified you will lose the ability to read those inputs.
I'm pretty sure you can ignore them and leave the hal file as is, since if not connected these inputs will read zero as default. 
You will need to modify .ini file for the homing part to tell linuxcnc that you will not use switches, see here: linuxcnc.org/docs/html/config/ini-homing.html  
Cap 6.Configuration
HOME_SEARCH_VEL 0
HOME_LATCH_VEL 0
HOME_USE_INDEX NO
Consider that the pinout of stepper pins on the board depends on the bin file you are using in the FPGA 

Hi muvideo,

okay thanks - i connected a stepper and i was wondering why it‘s not moving. I tried all axes/joints. (Card enabled and ready)So i will try to modify the home latching etc. all to zero. 
Thanks  all for the help!

vre wrote:

Hello.
If solder buffers for input can be used with H-bridge
for driving dc brushed servos with incremental encoder feedback ?
( pwm output / step-dir-quadrature output / encoder input / gpio )

What input buffer chips are needed and how to solder ? what modifications needed ?
example for 5A-75E v8 ?
(here does not have example for that version litex-cnc.readthedocs.io/en/latest/examples/index.html )

For changing the buffers you would need to get som 74LVC245 buffers. The letters LVC are important here, because these buffers are 5V tolerant, whilst Vcc can be 3.3 Volts. 

For removing the old buffers I use a small pliers and cut all the legs. After that it is easy to remove the remainder of the leg from the solder pads one by one with some flux. This method prevents ripping pads of from the board. 

​​​​​Now you have to cut the traces to pin 1 and 20. Pin1 is for direction and normally connected to 5 V. Pin 20 is Vcc and is also connected to the 5 V rail. Check and double check whether the pads are disconnected with a multimeter. 

Now you can solder the new buffer in place. Connect pin 1 to GND, for example make a jumper to pin 10 of the adjacent buffer. Pin 20 has to be connected to 3.3 volt supply, for example from the JTAG header. Now the conversion is done. 

Now for the first part of the question: the H-bridge. I mentioned this as a way to drive stepper motors. For a DC motor you can try it, but maybe the loop from encoder - > fpga - > linuxcnc - > fpga - > motor is too slow. The loop take 1 ms, which is 1 kHz. Please try, although you have to whip this together in the Hal. 
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