18f4431; driving a stepper IN HARDWARE mode

[Bruce]

Wow - nice catch on that one. It does appear to work. Cool idea, and thanks for the tip.

I wish I had a stepper motor board to test this on, but it does look good compared to the
UCN5804B datasheet for 2-phase & half-step drive sequences in MPSIM logic analyzer
.. when simulated for an 18F2431.

I already had a project in MPLAB using C18 for an 18F2431, so I tossed these values in
using your OVDCOND approach, and it looks good. Do these waveforms look good for both
2-phase & half-step?

If they do, and it's worthwhile .. I'll work up an example in PBP. I'm a total newbie when it
comes to steppers - so let me know if the control signals look OK.

Here's the C18 example I used to test & simulate, which should be super easy to translate
to PBP.

#include  p18f2431.h
#include  delays.h 
#pragma   config OSC=HS,LVP=OFF,WDTEN=OFF,MCLRE=OFF

union DutyCycle
{
  unsigned int Cycle;
  unsigned char wByte[2];
} Duty;


void main(void) 
{ 
   // Port init
   PORTB = 0;			      // clear port
   TRISB = 0;  		      // all outputs 

   // PCPWM init
   PTCON0 = 0;               // Free Running mode.
   PTPERL = 0;               //
   PTPERH = 1;               // PTPER = $0100 or 256d for ~19.45kHz
   PWMCON0 = 0b01011111;     // PWM[5:0] outputs enabled	
   PWMCON1 = 1;              // OVDCON synched to PWM time base
   DTCON = 0;                // zero dead-time
   PTCON1 = 0b10000000;      // PWM time base is ON
   
   Duty.Cycle = 1023;        // 19.5kHz has a 10-bit resolution.

   PDC0L=Duty.wByte[0];
   PDC0H=Duty.wByte[1];
   PDC1L=Duty.wByte[0];
   PDC1H=Duty.wByte[1];
   PDC2L=Duty.wByte[0];
   PDC2H=Duty.wByte[1];

   while(1)
    {
    /* // half step mode
    OVDCOND = 0b00000001;    // use override control to switch pwm pins
    Delay10TCYx(250);        // 500uS @ 20MHz
    OVDCOND = 0b00000011;
    Delay10TCYx(250);
    OVDCOND = 0b00000010;
    Delay10TCYx(250);
    OVDCOND = 0b00000110;
    Delay10TCYx(250);
    OVDCOND = 0b00000100;
    Delay10TCYx(250);
    OVDCOND = 0b00001100;
    Delay10TCYx(250);
    OVDCOND = 0b00001000;
    Delay10TCYx(250);
    OVDCOND = 0b00001001;
    Delay10TCYx(250); */
 
    // 2 phase mode
    OVDCOND = 0b00001001;
    Delay10TCYx(250);
    OVDCOND = 0b00000011;
    Delay10TCYx(250);
    OVDCOND = 0b00000110;
    Delay10TCYx(250);
    OVDCOND = 0b00001100;
    Delay10TCYx(250);

  } // End while(1) 

 } // End main

Half-step is 1st graphic, 2-phase is 2nd.