Encoder signals from servo to Beaglebone Black

[Antti]

Hello

I have made my DIY CNC milling machine with BBB and DIY cape. I used ARM.BeagleBone.Xylotex setup as base and modified that to work with my machine.
I used old Omron servo drivers and motors with DIR and STEP signals. It kinda works but now I'd like to add feedback signals from servos to BBB (2048 pls/rev).

So there is quadrature signals from X, Y and Z. I'm planning to use these pins P9:25, P9:27, P9:28, P9:29, P9:30, P9:31
I have understood that these pins are in PRU0 and first I have to config the those as "pruin" in setup.sh file?

Then the ini-file now:
[PRUCONF]
DRIVER=hal_pru_generic
CONFIG=pru=1 num_stepgens=3
PRUBIN=xenomai/pru_generic.bin

so can I change it to:
CONFIG=pru=0 num_stepgens=3 num_encoders=3

And how to I do the HAL wiring?

Here is the pins that are in use now:
P8.07 out # gpio2.2 Enable System
P8.10 in # gpio2.4 XLIM
P8.11 out # gpio1.13 X_Dir
P8.12 out # gpio1.12 X_Step
P8.13 out # gpio0.23 PWM0/SPINDLE
P8.14 in # gpio0.26 YLIM
P8.15 out # gpio1.15 Y_Dir
P8.16 out # gpio1.14 Y_Step
P8.18 in # gpio2.1 ZLIM
P9.15 out # gpio1.16 Z_Step
P9.23 out # gpio1.17 Z_Dir
P8.09 in # gpio2.5 STOPin
Are these step/dir signals used by PRU 1? Or can I use these with PRU 0?

[Charles Steinkuehler]

By default, the step/dir pins use GPIO access which is valid for either PRU core. The encoder signals, however, need to be direct PRU inputs, so the pins chosen and the pinmux setup will need to be valid for the specific PRU core you choose to run the driver. You setup the pin multiplexing outside of Machinekit/HAL, typically with a device-tree overlay, or the universal pinmux overlay and config-pin utility.

Some details on pin selection can be found in the PRU driver man page:

https://www.machinekit.io/docs/man/man9/hal_pru_generic/  

[Antti]

I got it working. At least with X axis. I have to do some pid and servo tuning, but at least the position feedback is working.

In the .ini file I have:

CONFIG=pru=0 num_stepgens=3 num_encoders=3 disabled=0

and in .hal file:

setp hpg.encoder.00.chan.00.A-pin 7
setp hpg.encoder.00.chan.00.B-pin 5
setp hpg.encoder.00.chan.00.scale [AXIS_0]ENCODER_SCALE

net motor.00.pos-fb <= hpg.encoder.00.chan.00.position axis.0.motor-pos-fb pid.0.feedback

And I didn't understand at first where I can get the number (A-pin 7 and B-pin 5).  They can be found in the pinmux.ods file (https://github.com/cdsteinkuehler/beaglebone-black-pinmux/blob/hal_pru_generic/pinmux.ods) from column K

A P9:25 -> pr1_pru0_pru_r31_1 -> 1

B P9:27 -> pr1_pru0_pru_r31_5 -> 5