Remora - Rpi Software Stepping Using External Microcontroller via SPI

• During the 'tail' end of movement, if you press F2, it will stop and continue the same movement when re-enabled with F2
• This behavior seems to be related to the DDS accumulator overflowing - this is consistent. Slowing movement near the edge of the int32 will cause this issue (when it overflows).
• The issue still occurs if you significantly reduce the DDS step bit (I had it at 10 in both fw and sw). Although it is less consistent, and occurs well within the int32 boundaries.

gtt38 wrote:

made some progress 

void loadModules()
{
    //Stepgen
    int joint;
    ptrInputs = &txData.inputs;
    ptrOutputs = &rxData.outputs;
    joint = 0;
    printf("\nCreate step generator for Joint %d\n", joint);
    ptrJointFreqCmd[joint] = &rxData.jointFreqCmd[joint];
    ptrJointFeedback[joint] = &txData.jointFeedback[joint];
    ptrJointEnable = &rxData.jointEnable;
    Module* joint0 = new Stepgen(PRU_BASEFREQ, joint, "PB_12", "PB_13", "PB_14", STEPBIT, *ptrJointFreqCmd[joint], *ptrJointFeedback[joint], *ptrJointEnable);
    baseThread->registerModule(joint0);
    
    //Blink
    Module* blinkServo = new Blink("PB_0", PRU_SERVOFREQ, 1);
    servoThread->registerModule(blinkServo);
    //Input
    Module* IN1 = new DigitalPin(*ptrInputs, 0, "PD_12", 0, true, NONE);
    servoThread->registerModule(IN1);
    // OUTPUTS
    Module* OUT1 = new DigitalPin(*ptrOutputs, 1, "PC_3", 0, false, NONE);
    servoThread->registerModule(OUT1);
    // PWM (not working)
    Module* pwm = new PWM(*ptrSetPoint, "PC_4");
    servoThread->registerModule(pwm);

@ Scott : everything works except PWM if you can help me

int sp = 0; //or which ever SP[i] you wish to use
ptrSetPoint[sp] = &rxData.setPoint[sp];
Module* pwm = new PWM(*ptrSetPoint[sp], pin, pwmMax);
servoThread->registerModule(pwm);

Rafal wrote:

Hi folks. I'm attempting to integrate Remora with my CNC minilathe and for the most part it's been trouble free. I'm new to LinuxCNC - so apologies for any obvious mistakes I make.

The setup is an rpi4 alongside STM32F106RCT6 based SKR mini 1.1 running a lightly modified version of develop. The modifications were just to setup SPI for this board (port A -> B, CS -> PA15) on the SKR_MINI_E3 target. The board is flashed by an STLINKV2.

On the pi side I've modified the xyz hal and ini files to suit my setup (2 joints, XZ config) and commented out spindle and other modules to ensure no interference.

I've run through and fixed a whole host of issues including SPI packet errors and configuration problems. Most of the solutions were already in this topic.

The long standing issue crops up enough to make the lathe unusable. You can move the system on either axis and when it stops or nears stopping, it (sometimes) suddenly jumps into motion (step change) and starts slowing down. This can be seen below. The position feedback value changes and the system compensates.

Some interesting observations:

• During the 'tail' end of movement, if you press F2, it will stop and continue the same movement when re-enabled with F2
• This behavior seems to be related to the DDS accumulator overflowing - this is consistent. Slowing movement near the edge of the int32 will cause this issue (when it overflows).
• The issue still occurs if you significantly reduce the DDS step bit (I had it at 10 in both fw and sw). Although it is less consistent, and occurs well within the int32 boundaries.
  
  
  Has anyone seen or fixed this behavior? I'd appreciate any insight!
  
  -Rafal