More problems :(
OK I thought, lets move this on and use a PIC capable of providing all 4 seperate PWM outputs. So after consultation via a few PMs with Steve and Darrel I've opted for a 16F676.
I've used a 20Mhz xtal, with 22pf caps between pins 2 and 3, wiper from 10K pot goes to pin 13 and PWM output on pin 8.
I've modified the code used for the 12F675, and compiled - no errors or warning, and loaded it into the PIC.
I then tested the code / hardware and I don't get the same performance as I did with the 12F. There is no responce from the loco until the pot is at mid point, at this stage the armature sings with a high pitch noise. Advancing the pot increases the speed, but I don't get anywhere like the slow crawl speeds I got with the 12F. I can also assume that the armature is warming as it smelt a little (carbon smell) after a short run.Code:@ __CONFIG _HS_OSC & _WDT_ON & _PWRTE_ON & _MCLRE_OFF ANSEL=%00110001 CMCON=7 TRISA=%11111111 'set PORTA as all input TRISC=%00000001 'set PORTC as all output apart from RC0 DEFINE OSC 20 CLEAR DEFINE ADC_BITS 8 ' Set number of bits in result DEFINE ADC_CLOCK 3 ' Set clock source (rc = 3) DEFINE ADC_SAMPLEUS 50 ' Set sampling time in microseconds INCLUDE "DT_INTS-14.bas" ; Base Interrupt System INCLUDE "SPWM_INT.bas" ; Software PWM module DEFINE SPWM_FREQ 100 ; SPWM Frequency DEFINE SPWM_RES 255 ; SPWM Resolution DutyVars VAR BYTE[3] ; DutyCycle Variables DutyVar1 VAR DutyVars[0] ; group them in an array for easy access DutyVar2 VAR DutyVars[1] ; with FOR loops etc. DutyVar3 VAR DutyVars[2] DutyVar4 VAR DutyVars[3] ASM SPWM_LIST macro ; Define Pin's to use for SPWM SPWM_PIN PORTC, 2, _DutyVar1 ; and the associated DutyCycle variables SPWM_PIN PORTC, 3, _DutyVar2 ; Notice the underscore before variables SPWM_PIN PORTC, 4, _DutyVar3 SPWM_PIN PORTC, 5, _DutyVar4 endm SPWM_INIT SPWM_LIST ; Initialize the Pins ENDASM ASM INT_LIST macro ; IntSource, Label, Type, ResetFlag? INT_Handler TMR1_INT, SPWMhandler, ASM, yes endm INT_CREATE ; Creates the interrupt processor ENDASM @ INT_ENABLE TMR1_INT ; enable Timer 1 interrupts ;_____________________________________________________________________________ Main: ADCIN 0, DUTYVAR1 ADCIN 1, DUTYVAR2 ADCIN 2, DUTYVAR3 ADCIN 3, DUTYVAR4 GOTO Main
I think its probably down to my poor understanding of Ansel etc.. so an constructive comments would be welcome.
Oh and I've not changed the driver stage yet as Alain suggested.
EDIT:: EDIT::
Changed the Xtal for a 4Mhz and the frequency of the noise has dropped.. but its still there and not the low growl that was produced by the 12F.. so it it a timing issue ??
Originally Posted by mister_e
mistake !!!!
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