This doesn't seem to be my week ... I had problems earlier with converting code from a PIC12F683 to a PIC12F1840 which thankfully was resolved yesterday (thanks Henrik!) but when I come back to something I thought was working fine, it's not.
I found examples of determining the direction of turn of a mechanical quadrature encoder. Darrel helped way back with some of it and all was well until late last night when I thought I'd better retest this after working on other parts of the project. Lo and behold, the MotorRPM variable isn't going up or down steadily but rather goes up by one or two but could just as easily go down (when turning the knob in the same direction). I did spend the first part of the year converting from using PBP's HPWM on CCP1/2 (which are ECCP modules on the 16F1825) to CCP3/4 (regular CCP modules) but at the time I'm fairly certain I tested the quadrature part and it worked OK.
Here's my code (edited for clarity):
Here's a video which shows the problem (I hope):
Here's my schematic:
Attachment 6893
Again, AFAIK nothing has changed in the two months since I last worked on this code and all was well.
Does anyone see where I'm going wrong? Here's what I've tried:
Something to do with Timer2 & PWM on CCP3/4? Bad IOC interrupt config? What's strange is that the quad encoder has a pushbutton knob and that's working just fine (although it's not using an interrupt).
I found examples of determining the direction of turn of a mechanical quadrature encoder. Darrel helped way back with some of it and all was well until late last night when I thought I'd better retest this after working on other parts of the project. Lo and behold, the MotorRPM variable isn't going up or down steadily but rather goes up by one or two but could just as easily go down (when turning the knob in the same direction). I did spend the first part of the year converting from using PBP's HPWM on CCP1/2 (which are ECCP modules on the 16F1825) to CCP3/4 (regular CCP modules) but at the time I'm fairly certain I tested the quadrature part and it worked OK.
Here's my code (edited for clarity):
Code:
' ***************************************************************
' Pin Connections
' ***************************************************************
' RA0 -> B pin of rotary encoder
' RA1 -> A pin of rotary encoder
' RA2/CCP3 -> Stbd motor PWM output (motor 1)
' RA3/MCLR -> Button switch pin of rotary encoder
' RC0 -> Stbd motor direction signal (motor 1)
' RC1/CCP4 -> Port motor PWM output (motor 2)
' RC2 -> Port motor direction signal (motor 2)
' RC4/Tx -> Serial LCD output
' RC5/Rx -> Serial input
DEFINE OSC 16 ; Set oscillator 16Mhz
' ***************************************************************
' Device Fuses
' ***************************************************************
#CONFIG
__config _CONFIG1, _FOSC_INTOSC & _WDTE_ON & _PWRTE_ON & _MCLRE_OFF & _CP_OFF & _CPD_OFF
__config _CONFIG2, _PLLEN_OFF & _STVREN_ON & _BORV_LO & _LVP_OFF
#ENDCONFIG
' ***************************************************************
' Initialization
' ***************************************************************
OSCCON = %01111000 ' 16MHz internal osc
pause 100 ' As advised by Darrel Taylor for EEPROM issue
ANSELA = 0 ; Digital only for all PortA pins
ANSELC = 0 ; Diginal only for all PortC pins
TRISA = %00001011 ' Make PORTA pins 0-1 input for rotary encoder,
' pin 3 for rotary button
TRISC = 0 ' Make all PORTC pins output
' The INTEDG bit of the OPTION_REG register determines on which edge the
' interrupt will occur. When the INTEDG bit is set, the rising edge will
' cause the interrupt. When the INTEDG bit is clear, the falling edge will
' cause the interrupt.
OPTION_REG.6 = 1 ' 1=Rising edge (default) or button "PRESS";
' 0=Falling edge or button "RELEASE"
Old_Bits VAR BYTE
New_Bits VAR BYTE
RotEncDir VAR BIT ' 1=CW, 0=CCW
' Rot Enc pin A connected to PortA.1;
' Rot Enc pin B connected to PortA.0
Old_RPM VAR BYTE
i VAR BYTE
' ***************************************************************
' Set up registers for PWM on CCP3 & CCP4
' ***************************************************************
CCP3CON = %00001100 ; Use CCP3 in PWM mode
CCP4CON = %00001100 ; Use CCP4 in PWM mode
T2CON = %00000101 ; Timer2 on with 1:4 prescaler
PR2 = 62 ; For 16Mhz OSC the desired output freq of 15,873Hz is
; achieved with this PR2 value (8-bit resolution
; with 1:4 prescaler)
; PWM freq must be ~ 16-20kHz to reduce noise
PreSpinVal CON 17 ; value to subtract from MinDuty for motor spin up
MinDuty CON 75 ; 75 when max duty = 250 (8-bit resolution)
;SpinUpPause CON 17 ; Pause during motor spin up
SpinUpPause VAR BYTE ; Pause during motor spin up
SpinUpPause = 17
#IFDEF USE_LCD_FOR_DEBUG
SpinUpPause = 12 ; Subtract 5ms pause when outputting to LCD
#ENDIF
MaxDuty VAR WORD ; According to Darrel:
; MaxDuty = (PR2 + 1) * 4
MaxDuty = (PR2 + 1) * 4 ; 252 but with prescaler resolution it's actually 250
DutyVar3 VAR WORD ; temp variable to store duty variable for CCP3
DutyVar4 VAR WORD ; temp variable to store duty variable for CCP4
TimeCnt VAR Word
' ***************************************************************
' Includes
' ***************************************************************
INCLUDE "DT_INTS-14.bas" ' Base Interrupt System
INCLUDE "ReEnterPBP.bas" ' Include if using PBP interrupts
' --> copy both files to PBP main folder
' (i.e. c:\pbp3)
' ***************************************************************
' EEPROM Variables
' ***************************************************************
MotorRPM_Default CON 177
EE_MotorRPM DATA MotorRPM_Default
MotorRPM VAR BYTE
READ EE_MotorRPM, MotorRPM
PortEngDir_Default CON 0
EE_PortEngDir DATA PortEngDir_Default
PortEngDir VAR BYTE
READ EE_PortEngDir, PortEngDir
' ***************************************************************
' ASM Interrupt Definitions
' ***************************************************************
ASM
INT_LIST macro ; IntSource, Label, Type, ResetFlag?
INT_Handler IOC_INT, _RotEncAdjust, PBP, yes
endm
INT_CREATE ; Creates the interrupt processor
ENDASM
' ***************************************************************
' Set default values
' ***************************************************************
Old_RPM = MotorRPM
Old_Bits = PORTA & (%00000011)
' Enable interrupts on RPM control now that motors are fully spun up
INTCON = %10001000 ' Global int enabled, IOCI enabled,
' INTF flag bit 0 clr, IOCI flag bit 0 clr
IOCAP.0 = 1 ' Enable positive (rising edge) change
IOCAP.1 = 1 ' Enable positive (rising edge) change
IOCAN.0 = 1 ' Enable negative (falling edge) change
IOCAN.1 = 1 ' Enable negative (falling edge) change
IOCAF.0 = 0 ' Clear interupt-on-change flag
IOCAF.1 = 0 ' Clear interupt-on-change flag
@ INT_ENABLE IOC_INT ; Interrupt-on-Change interrupt
Main:
' Check if motor RPM has changed
IF MotorRPM <> Old_RPM Then
Old_RPM = MotorRPM
GOSUB ChngMotorHPWM
EndIF
TimeCnt = 0
While ButtonPress = 0
TimeCnt = TimeCnt + 1
Pause 10
If TimeCnt > 500 Then BtnAction
Wend
BtnAction:
If TimeCnt > 0 and TimeCnt < 200 Then
PortEngDir = PortEngDir + 1
If PortEngDir > 1 Then PortEngDir = 0
WRITE EE_PortEngDir, PortEngDir
#IFDEF USE_LCD_FOR_DEBUG
HSEROUT [LCD_INST, LCD_CLR]
pause 5
HSEROUT ["PortEngDir=", DEC PortEngDir, " ", 13, 10] ' Send text followed by carriage return and linefeed
#ENDIF
GOSUB ReversePortEng
ElseIf TimeCnt >= 200 Then
WRITE EE_MotorRPM, MotorRPM_Default ; restore Default value
MotorRPM = MotorRPM_Default
EndIf
GOTO Main
' ***************************************************************
' [IOC - interrupt handler]
' ***************************************************************
RotEncAdjust:
New_Bits = PORTA & (%00000011)
IF (New_Bits & %00000011) = (Old_Bits & %00000011) Then DoneRotEnc
RotEncDir = New_Bits.1 ^ Old_Bits.0
IF RotEncDir = 1 Then
; CW rotation - increase speed but only to a max of 'MaxDuty'
IF MotorRPM < MaxDuty then MotorRPM = MotorRPM + 1
Else
' CCW rotation - decrease speed to a min of 0
IF MotorRPM > 0 Then MotorRPM = MotorRPM - 1
EndIF
WRITE EE_MotorRPM, MotorRPM
pause 100
DoneRotEnc:
Old_Bits = New_Bits
IOCAF.0 = 0 ' Clear interrupt flags
IOCAF.1 = 0
@ INT_RETURNHere's my schematic:
Attachment 6893
Again, AFAIK nothing has changed in the two months since I last worked on this code and all was well.
Does anyone see where I'm going wrong? Here's what I've tried:
- Swapped out the quad encoder with a spare one (same model)
- Swapped out the PIC and programmed another one
- Replaced the 10k resistors that tie the encoder's A/B outputs to +5V
- Double-checked the connections
Something to do with Timer2 & PWM on CCP3/4? Bad IOC interrupt config? What's strange is that the quad encoder has a pushbutton knob and that's working just fine (although it's not using an interrupt).