Thanks for this answer.
I would like to install RTAI due to the jitter in my setup, which is around 70k.
I'm using 4 stepper motors with encoders (closed loop) and a USC board from PICO.
Sometimes, though not very often, I get an "Unexpected realtime delay" message.
Do you think this could be related to the jitter amount?
I've tried every optimization I could find in the BIOS...
Just having a look at the PICO config, is the base thread used ? From a quick look nothing appears to attach to the base thread. Which would lead me to think that a simple RT_PREEMPT kernel would be suffice. The PICO board would seem to operate in a simialr way to a mesa 7i90 using the EPP protocol. IE using the parallel port to send timing info to a FPGA.
You're right, into the HAL file, there is only mention of servo-thread:
Code:
# Generated by stepconf 1.1 at Tue Jan 28 10:21:07 2025
# Si vous modifiez ce fichier, il sera
# écrasé quand vous relancerez Stepconf
loadrt [KINS]KINEMATICS
loadrt [EMCMOT]EMCMOT servo_period_nsec=[EMCMOT]SERVO_PERIOD num_joints=[KINS]JOINTS num_spindles=[TRAJ]SPINDLES
# next load the PID module, for four PID loops
loadrt pid num_chan=4
loadrt plasmac
loadrt hal_ppmc epp_dir=1
# make some signals for the scope for tuning.
loadrt ddt count=4
# add components for E-stop logic
loadrt estop_latch count=1
loadrt and2 count=1
# set up the realtime thread
# read inputs first
addf ppmc.0.read servo-thread
# then run the motion controller
addf motion-command-handler servo-thread
addf and2.0 servo-thread
addf estop-latch.0 servo-thread
addf motion-controller servo-thread
# then the PID loops
addf pid.0.do-pid-calcs servo-thread
addf pid.1.do-pid-calcs servo-thread
addf pid.2.do-pid-calcs servo-thread
addf pid.3.do-pid-calcs servo-thread
# write outputs last
addf ppmc.0.write servo-thread
# ---PLASMA INPUT DEBOUNCE---
loadrt dbounce names=db_breakaway,db_float,db_ohmic,db_arc-ok
addf db_float servo-thread
addf db_ohmic servo-thread
addf db_breakaway servo-thread
addf db_arc-ok servo-thread
# ---JOINT ASSOCIATED WITH THE Z AXIS---
net plasmac:axis-position joint.2.pos-fb => plasmac.axis-z-position
# ---PLASMA INPUTS---
# ---all modes---
net plasmac:float-switch => db_float.in
net plasmac:breakaway => db_breakaway.in
net plasmac:ohmic-probe => db_ohmic.in
net plasmac:ohmic-sense-in => plasmac.ohmic-sense-in
# ---modes 0 & 1
net plasmac:arc-voltage-in => plasmac.arc-voltage-in
# ---modes 1 & 2
net plasmac:arc-ok-in => db_arc-ok.in
# ---mode 2
net plasmac:move-up => plasmac.move-up
net plasmac:move-down => plasmac.move-down
# ---PLASMA OUTPUTS---
# ---all modes---
net plasmac:ohmic-enable <= plasmac.ohmic-enable
net plasmac:scribe-arm <= plasmac.scribe-arm
net plasmac:scribe-on <= plasmac.scribe-on
# connect limit/home switch outputs to motion controller
net Xminlim <= ppmc.0.din.01.in
net Xminlim => joint.0.neg-lim-sw-in
net Xmaxlim <= ppmc.0.din.02.in
net Xmaxlim => joint.0.pos-lim-sw-in
net Xhome <= ppmc.0.din.00.in
net Xhome => joint.0.home-sw-in
net Yminlim <= ppmc.0.din.05.in
net Yminlim => joint.1.neg-lim-sw-in
net Ymaxlim <= ppmc.0.din.06.in
net Ymaxlim => joint.1.pos-lim-sw-in
net Yhome <= ppmc.0.din.04.in
net Yhome => joint.1.home-sw-in
net Zminlim <= ppmc.0.din.09.in
net Zminlim => joint.2.neg-lim-sw-in
net Zmaxlim <= ppmc.0.din.10.in
net Zmaxlim => joint.2.pos-lim-sw-in
net Zhome <= ppmc.0.din.08.in
net Zhome => joint.2.home-sw-in
net Aminlim <= ppmc.0.din.12.in
net Aminlim => joint.3.neg-lim-sw-in
net Amaxlim <= ppmc.0.din.13.in
net Amaxlim => joint.3.pos-lim-sw-in
net Ahome <= ppmc.0.din.11.in
net Ahome => joint.3.home-sw-in
# connect index pulses to motion controller
# uncomment these lines only if you have a Rev 2 USC board
# newsig Xindex bit
# newsig Yindex bit
# newsig Zindex bit
# newsig Aindex bit
# linksp Xindex <= ppmc.0.encoder.00.index-enable
# linksp Xindex => joint.0.index-enable
# linksp Yindex <= ppmc.0.encoder.01.index-enable
# linksp Yindex => joint.1.index-enable
# linksp Zindex <= ppmc.0.encoder.02.index-enable
# linksp Zindex => joint.2.index-enable
# linksp Aindex <= ppmc.0.encoder.03.index-enable
# linksp Aindex => joint.3.index-enable
#
# Connect I/O controller I/Os
#
# connect e-stop write/sense to I/O controller
# and univstep's fault with estop's output, so estop FF is reset, but
# prevent continued estop signal from univstep from holding FF cleared
net ppmcEstop ppmc.0.din.15.in-not
net ppmcEstop and2.0.in0
net EstopOkIn estop-latch.0.fault-in
net EstopOkIn and2.0.out
net EstopOkOut <= ppmc.0.dout.07.out
net EstopOkOut iocontrol.0.emc-enable-in
net EstopOkOut estop-latch.0.ok-out
net EstopOkOut and2.0.in1
net emc-estop-out iocontrol.0.user-enable-out
net emc-estop-out estop-latch.0.ok-in
net emc-estop-reset iocontrol.0.user-request-enable
net emc-estop-reset estop-latch.0.reset
net emc-estop-out estop-latch.0.ok-in
# connect spindle fwd/rev to I/O controller
net SpindleFwd <= ppmc.0.dout.00.out
net SpindleFwd => spindle.0.forward
net SpindleRev <= ppmc.0.dout.01.out
net SpindleRev => spindle.0.reverse
# connect spindle brake to I/O controller
net SpindleBrakeOn <= ppmc.0.dout.02.out
net SpindleBrakeOn => spindle.0.brake
# connect mist/flood coolant to I/O controller
net MistOn <= ppmc.0.dout.03.out
net MistOn => iocontrol.0.coolant-mist
net FloodOn <= ppmc.0.dout.04.out
net FloodOn => iocontrol.0.coolant-flood
# connect position feedback signals to encoders
net Xpos-fb <= ppmc.0.encoder.00.position
net Ypos-fb <= ppmc.0.encoder.01.position
net Zpos-fb <= ppmc.0.encoder.02.position
net Apos-fb <= ppmc.0.encoder.03.position
# get feedback scaling from ini file
setp ppmc.0.encoder.00.scale [JOINT_0]INPUT_SCALE
setp ppmc.0.encoder.01.scale [JOINT_1]INPUT_SCALE
setp ppmc.0.encoder.02.scale [JOINT_2]INPUT_SCALE
setp ppmc.0.encoder.03.scale [JOINT_3]INPUT_SCALE
# connect PID output signals to step generators
net Xoutput => ppmc.0.stepgen.00.velocity
net Youtput => ppmc.0.stepgen.01.velocity
net Zoutput => ppmc.0.stepgen.02.velocity
net Aoutput => ppmc.0.stepgen.03.velocity
# connect axis enables to step generators
net Xenable => ppmc.0.stepgen.00.enable
net Yenable => ppmc.0.stepgen.01.enable
net Zenable => ppmc.0.stepgen.02.enable
net Aenable => ppmc.0.stepgen.03.enable
# set output scaling from ini file
# input and output scales should (normally) be the same for a USC
setp ppmc.0.stepgen.00.scale [JOINT_0]OUTPUT_SCALE
setp ppmc.0.stepgen.01.scale [JOINT_1]OUTPUT_SCALE
setp ppmc.0.stepgen.02.scale [JOINT_2]OUTPUT_SCALE
setp ppmc.0.stepgen.03.scale [JOINT_3]OUTPUT_SCALE
# add a couple of tuning test links
# if these are useful will want to add them to the other axes as well
# or make these setup with the tuning script
# net Xoutput ddt.0.in
# net Xpos-fb ddt.1.in
# HAL config file for servos -- expanded from core_servo.hal
# for a full four axis setup
# create four position feedback signals
# connect position feedback to PID loop
net Xpos-fb => pid.0.feedback
net Ypos-fb => pid.1.feedback
net Zpos-fb => pid.2.feedback
net Apos-fb => pid.3.feedback
# connect position feedback to motion module
net Xpos-fb => joint.0.motor-pos-fb
net Ypos-fb => joint.1.motor-pos-fb
net Zpos-fb => joint.2.motor-pos-fb
net Apos-fb => joint.3.motor-pos-fb
# create PID to DAC output signals
# connect output signals to output of PID loops
net Xoutput <= pid.0.output
net Youtput <= pid.1.output
net Zoutput <= pid.2.output
net Aoutput <= pid.3.output
# set PID loop output limits to +/-1.00
setp pid.0.maxoutput [JOINT_0]PID_MAX_VEL
setp pid.1.maxoutput [JOINT_1]PID_MAX_VEL
setp pid.2.maxoutput [JOINT_2]PID_MAX_VEL
setp pid.3.maxoutput [JOINT_3]PID_MAX_VEL
# set PID loop gains
setp pid.0.Pgain [JOINT_0]P
setp pid.0.Igain [JOINT_0]I
setp pid.0.Dgain [JOINT_0]D
setp pid.0.bias [JOINT_0]BIAS
setp pid.0.FF0 [JOINT_0]FF0
setp pid.0.FF1 [JOINT_0]FF1
setp pid.0.FF2 [JOINT_0]FF2
setp pid.0.deadband [JOINT_0]DEADBAND
setp pid.1.Pgain [JOINT_1]P
setp pid.1.Igain [JOINT_1]I
setp pid.1.Dgain [JOINT_1]D
setp pid.1.bias [JOINT_1]BIAS
setp pid.1.FF0 [JOINT_1]FF0
setp pid.1.FF1 [JOINT_1]FF1
setp pid.1.FF2 [JOINT_1]FF2
setp pid.1.deadband [JOINT_1]DEADBAND
setp pid.2.Pgain [JOINT_2]P
setp pid.2.Igain [JOINT_2]I
setp pid.2.Dgain [JOINT_2]D
setp pid.2.bias [JOINT_2]BIAS
setp pid.2.FF0 [JOINT_2]FF0
setp pid.2.FF1 [JOINT_2]FF1
setp pid.2.FF2 [JOINT_2]FF2
setp pid.2.deadband [JOINT_2]DEADBAND
setp pid.3.Pgain [JOINT_3]P
setp pid.3.Igain [JOINT_3]I
setp pid.3.Dgain [JOINT_3]D
setp pid.3.bias [JOINT_3]BIAS
setp pid.3.FF0 [JOINT_3]FF0
setp pid.3.FF1 [JOINT_3]FF1
setp pid.3.FF2 [JOINT_3]FF2
setp pid.3.deadband [JOINT_3]DEADBAND
# create four position command signals
# connect position commands to motion controller
net Xpos-cmd <= joint.0.motor-pos-cmd
net Ypos-cmd <= joint.1.motor-pos-cmd
net Zpos-cmd <= joint.2.motor-pos-cmd
net Apos-cmd <= joint.3.motor-pos-cmd
# connect position commands to PID input
net Xpos-cmd => pid.0.command
net Ypos-cmd => pid.1.command
net Zpos-cmd => pid.2.command
net Apos-cmd => pid.3.command
# create bit signals to enable/disable the PID loops
# connect the signals to the motion controller
net Xenable <= joint.0.amp-enable-out
net Yenable <= joint.1.amp-enable-out
net Zenable <= joint.2.amp-enable-out
net Aenable <= joint.3.amp-enable-out
# connect the signals to the PID blocks
net Xenable => pid.0.enable
net Yenable => pid.1.enable
net Zenable => pid.2.enable
net Aenable => pid.3.enable
But i'm not an expert in this type of configuration...
