topic Help with triggering A/D from PWM in MC56F84789 in Digital Signal Controllers

Help with triggering A/D from PWM in MC56F84789

ptszymanski — Mon, 21 Aug 2017 14:56:58 GMT

I am attempting to get the ADC12 and ADC16 to trigger from the PWMA output of SM0, SM1, and SM2 modules. I have set the XBARA_SEL0, 1, 2 registers to map the pwm module's PWMA output to the ADC input, and similarly for the PWMB and and the ADC16.

    XBARA_SEL0 = 0x140C;
    XBARA_SEL1 = 0x160D;
    XBARA_SEL2 = 0x180E;

When I run the code, the PWMA_SMxTCTRL register reads 0x0004 instead of 0x8004 (which is supposed to be setting the trigger for PWMA as a trigger). The code does attempt to set the bit in PWMA_Init() in the PWMA.c module generated by ProcessorExpert (and similarly for SM1 and SM2),

/* PWMA_SM0TCTRL: PWAOT0=1,PWBOT1=0,??=0,??=0,??=0,??=0,??=0,??=0,??=0,??=0,OUT_TRIG_EN=4 */
setReg16(PWMA_SM0TCTRL, 0x8004U);

but it doesn't get set when I look at it using CodeWarrior. Any idea what is wrong? Is this even possible with this chip?

Re: Help with triggering A/D from PWM in MC56F84789

ptszymanski — Mon, 21 Aug 2017 18:20:15 GMT

Thanks for reading, I figured it out...

Re: Help with triggering A/D from PWM in MC56F84789

xiangjun_rong — Tue, 22 Aug 2017 05:58:34 GMT

Hi, Peter,

Pls refer to the screenshot in the MC56F847xxRM.pdf, if you want to use PWMA0_Trig0 to trigger ADCA, this is the crossbar setting:

XBARA_SEL6 = 20; //the 20 means XBAR_IN20, XBAR_OUT12 is the ADCA trigger

If you want to use PWMA_Trig0 to trigger SAR ADC

XBARA_SEL7 = 20; //the 20 means XBAR_IN20

Regarding the PWMA triggering setting:

setReg16(PWMA_SM0TCTRL, 0x04U); //use VAL2 to trigger, do not set the PWMAOT0 or PWMAOT1 bits

Hope it can help you

Xiangjun rong