QE8 Timer Initialization for Edge-Aligned PWM Mode

paul_1951 — Mon, 04 Nov 2013 22:39:41 GMT

Hi All,

We are trying to setup a QE8 to produce a variable duty cycle for a motor drive. The timer is set to run continuously.

The WDT is disabled.

Below is the code we are using. The output pin on the 28 pin SOIC has been re-routed to PC0/TPM1CH2.

The toggle output on channel match works fine and we get a 50% DC pulse at the desired period.

The problem we have is changing to Edge-aligned PWM. It just does not work.

Obviously we are missing something, any help is appreciated.

; setup timer period, values are for 100Hz [$0520] [100 prescale]

mov #$05,TPM1MODH ;load period into high byte of timer modulo register

mov #$20,TPM1MODL ;load period into low byte of timer modulo register

; setup timer pulse width, larger value decreases pulse width

mov #$01,TPM1C2VH ;load output compare into high byte of timer value register

mov #$10,TPM1C2VL ;load output compare into low byte of timer value register

mov #%00001100,TPM1SC ;CPWMS clear for edge aligned PWM, bus clock source, prescale

; mov #%00101000,TPM1C2SC ;output compare, high true PWM pulse - THIS PRODUCES NO OUTPUT, PC0 STAYS LOW

mov #%00010100,TPM1C2SC ;output compare, high true PWM pulse - THIS WORKS

aa bra aa : stay in loop

Re: QE8 Timer Initialization for Edge-Aligned PWM Mode

iansmusical — Tue, 05 Nov 2013 08:16:16 GMT

Hi Paul,

My current home research project is an RGB LED controller which uses a QE device with edge aligned PWM. If you look in the thread below I attached my source when having an issue with the MOD value update in the TOF isr, maybe it will help you a little!?

QE8 TPMxMOD update in TOF ISR?

Thanks,

Ian

topic QE8 Timer Initialization for Edge-Aligned PWM Mode in 8-bit Microcontrollers

QE8 Timer Initialization for Edge-Aligned PWM Mode

Re: QE8 Timer Initialization for Edge-Aligned PWM Mode