MSP432P401R: Triggering an ADC14 sample using TimerA0[1] in continuous mode

Part Number: MSP432P401R

Hello,

I'm working on an application where I want to sample a signal at a given rate (22.05 kHz, but this doesn't really matter). I am also doing some processing on that signal, so I would like to contain the processing portion of my program in a timer interrupt, and the sampling in an ADC interrupt. I have configured the Timer and ADC14 peripherals as follows:

void TIMER_init(void) {

	/* enable interrupts */
	NVIC->ISER[0] |= 1 << ((TA0_0_IRQn) & 31);
	NVIC->ISER[0] |= 1 << ((TA0_N_IRQn) & 31);

	TIMER_A0->CCTL[1] |=
		TIMER_A_CCTLN_OUTMOD_7 |		//something about resetting, unsure
		CCIE;						//enable interrupts for TIMER_AO[1]
	
	/* initialize counter comparison register TEMPORARY FIX */
    TIMER_A0->CCR[1] = 1000;
    
    /* set clock source and mode */
	TIMER_A0->CTL |= 
		TIMER_A_CTL_SSEL__SMCLK |	// SMCLK as source
    		TIMER_A_CTL_ID__8 |			// clock divider (1,2,4,8)
		TIMER_A_CTL_MC__CONTINUOUS |	// continuous mode
		TIMER_A_CTL_CLR;				// clear timer count
    
    TIMER_A0->EX0 |= TAIDEX__1; //Extended clock divider (1,2,3,4,5,6,7,8)
}

void ADC14_init(void) {
	/* enable interrupts */
	NVIC->ISER[0] |= 1 << ((ADC14_IRQn) & 31);

	/* configure MIC_OUTPUT for ADC14 */
	MIC_OUT_PORT->DIR &= ~MIC_OUT_PIN;
	MIC_OUT_PORT->SEL1 |= MIC_OUT_PIN;
	MIC_OUT_PORT->SEL0 |= MIC_OUT_PIN;

	/* disable conversion to allow configuration */
	ADC14->CTL0 &= ~ADC14_CTL0_ENC;
	
	/* configure control register 0 */
	ADC14->CTL0 =
		ADC14_CTL0_SHS_1 |	// start conversion from TA0.1
		ADC14_CTL0_SHP |	// pulse mode
		ADC14_CTL0_SHT0_2 |	// 16 clock cycle sample time
		ADC14_CTL0_ON;		// turn ADC module on
		
	/* configure control register 1 */
	ADC14->CTL1 = 
		ADC14_CTL1_RES__14BIT;
	
	/* choose A10 as source */
	ADC14->MCTL[0] |= MIC_OUT_CHANNEL;
	
	/* enable interrupt when conversion on A0 is complete */
	ADC14->IER0 = ADC14_IER0_IE0;
	
	/* enable conversions */
	ADC14->CTL0 |= ADC14_CTL0_ENC;
}

and a minimal example of my interrupt service routines are here

// TIMER ISR
void TA0_N_IRQHandler(void) {
	timer_counter++;
	TIMER_A0->CCR[1] += period;
	TIMER_A0->CCTL[1] &= ~CCIFG;
}

// ADC ISR
void ADC14_IRQHandler(void) {
	if(++index >= 20000) { index = 0; }
	adc_counter++;
	audio[index] = ADC14->MEM[0]; //get sample, clear flag
}

When I run this, the Timer's ISR clearly runs (by observing the value of timer_counter in memory), but the ADC ISR seemingly runs once (the value of adc_counter increments once and then seemingly stops).

I think I'm not properly grasping how to trigger the ADC14 conversion from the timer, and how that can be tied into an ISR. I'm looking for suggestions on how to configure or implement this differently.

Thanks,

Thomas