,,, ;HC11 PWM Motor Control Example
,,, ;Demonstrates ADC and Timer Output Capture functions
,,,
,,, PORTA             equ      $1000
,,, PORTC             equ      $1003
,,, PORTB             equ      $1004
,,, DDRC              equ      $1007
,,, TOC1              equ      $1016
,,, TOC2              equ      $1018
,,, TCTL1             equ      $1020
,,, TCTL2             equ      $1021
,,, TMSK1             equ      $1022
,,, TFLG1             equ      $1023
,,, TMSK2             equ      $1024
,,, PACTL             equ      $1026
,,, ADCTL             equ      $1030
,,, ADR1              equ      $1031
,,, ADR2              equ      $1032
,,,
,,,                 org $F000
,,,
F000,8E 00 FF,start:, start:          lds  #$FF
,,,
F003,86 FF,,                 ldaa #$FF                       ;Port C is output
F005,B7 10 07,,                 staa DDRC
,,,
F008,86 80,,                 ldaa #$80                       ;Enable OC1 interrupts.
F00A,B7 10 22,,                 staa TMSK1                      ;
,,,
F00D,86 02,,                 ldaa #$2                        ;Set the prescaler (divide by 16)
F00F,B7 10 24,,                 staa TMSK2
,,,
F012,86 80,,                 ldaa #$80                       ;Enable PA7 as output
F014,B7 10 26,,                 staa PACTL
,,,
,,,
F017,86 10,,                 ldaa #$10                       ;Start first ADC conversion - multi mode enable
F019,B7 10 30,,                 staa ADCTL
,,,
F01C,CC 01 00,,                 ldd #$0100                      ;Load the capture register
F01F,FD 10 16,,                 std TOC1
,,,
F022,0E,,                 cli                             ;Enable interupts
,,,
F023,3E,loop, loop            wai
F024,20 FD,,                 bra loop
,,,
,,,
,,,
,,, ;OC1 interrupt service
F026,86 10,oc1f, oc1f            ldaa #$10                       ;Start another ADC conversion
F028,B7 10 30,,                 staa ADCTL
,,,
F02B,B6 10 31,,                 ldaa ADR1                       ;Read the pot position from ADC channel 1
F02E,B7 10 04,,                 staa PORTB                      ;Display it
,,,
F031,80 7F,,                 suba #127                       ;0x7F is zero reference.
,,,
F033,26 09,,                 bne oc1f_ne                     ;Jump if values not same
,,,
,,, ;Set Both outputs low. Motor is stationary
F035,5F,,                 clrb
F036,F7 10 00,,                 stab PORTA                      ;Both OC1 and OC2 outputs low
F039,F7 10 20,,                 stab TCTL1                      ;TOC2 mode is disabled
F03C,20 21,,                 bra done
,,,
,,, ;Non-zero drive - decide if +ve or -ve:
,,,
F03E,25 10,oc1f_ne, oc1f_ne         bcs oc1f_cs
,,,
,,, ;Positive result - motor spins clockwise:
,,,
F040,C6 40,,                 ldab #$40                       ;Port A drives this value:
F042,F7 10 00,,                 stab PORTA
F045,5F,,                 clrb                            ;Release TOC2 latch - Port A acquires value, above.
F046,F7 10 20,,                 stab TCTL1
F049,C6 40,,                 ldab #$40                       ;TOC 2 output toggles on OC2 event; motor drive stops.
F04B,F7 10 20,,                 stab TCTL1
F04E,20 0F,,                 bra done
,,,
,,, ;Negative result - motor spins anti-clockwise:
,,,
F050,C6 80,oc1f_cs, oc1f_cs         ldab #$80                       ;Port A drives this value:
F052,F7 10 00,,                 stab PORTA
F055,5F,,                 clrb                            ;Release TOC2 latch - Port A acquires value, above.
F056,F7 10 20,,                 stab TCTL1
F059,C6 40,,                 ldab #$40                       ;TOC 2 output toggles on OC2 event; motor drive stops.
F05B,F7 10 20,,                 stab TCTL1
F05E,40,,                 nega                            ;Invert result -> 0xFF -> 0x01 etc.
,,,
,,, ;Now set up TOC2 to trigger at a time forward of TOC1. This means that the motor will
,,, ;be powered for the number of ticks in ACCA * 256.
,,,
F05F,16,done:, done:           tab                             ;TOC 2 is set to trigger after this no of cycles.
F060,4F,,                 clra
F061,59,,                 rolb
F062,49,,                 rola
F063,59,,                 rolb
F064,49,,                 rola
F065,59,,                 rolb
F066,49,,                 rola
F067,59,,                 rolb
F068,49,,                 rola
F069,59,,                 rolb
F06A,49,,                 rola
F06B,F3 10 16,,                 addd TOC1
F06E,FD 10 18,,                 std TOC2
,,,
F071,CC 10 00,,                 ldd #$1000
F074,F3 10 16,,                 addd TOC1
F077,FD 10 16,,                 std TOC1
,,,
F07A,86 80,,                 ldaa #$80                       ;Clear the TOC 1 interrupt
F07C,B7 10 23,,                 staa TFLG1
F07F,3B,,                 rti
,,,
,,,
,,, ;Interrupt Vectors
,,,
,,,                 org $FFE8
FFE8,F0 26,,                 dw oc1f
,,,
,,,                 org $FFFE
FFFE,F0 00,,                 dw start
,,,