Posted on May 17, 2011 at 12:22I am having difficulty getting DMA to work with ADC1 working on the STM3210B-EVAL board. I believe I have correctly configured the DMA, clocks, and ADC1. The ADC appears to be working OK.
I want to convert channels 10-13, 16, and 17. I am starting conversion by writing the ADON bit. Unfortunately, I can't examine the DMA registers with my probe for some reason. After starting a conversion, I wait for the end of conversion and look at my memory buffer, expecting to see the results of all six conversions. Instead, I see all 0s, although what appears to be a valid result for the temperature sensor is in the ADC_DR register. This is a mystery in itself as the reference voltage should be the last value converted :-).
I have examined the DMA examples from the firmware library with no luck. Can anyone see something I am missing in the following code snippets?
/********* clock configuration ***************/
CLOCKRCC->RCC_CR = 0x00010000; // PLL off, clock source is HSE
CLOCKRCC->RCC_CFGR = 0x04010000; // System clock on MCO output pin,
CLOCKRCC->RCC_AHBENR = 0x00000015; // DMA clock enabled
CLOCKRCC->RCC_APB2ENR= 0x00005A1D; // USART1, SPI1, TIM1, ADC1,
// GPIOC, GPIOB, GPIOA clocks enabled
CLOCKRCC->RCC_APB1ENR= 0x12002004; // PWR, CAN, SPI2, TIM4 clocks enabled
/******* GPIOC configuration (ADC10-13) ************/
GPIOC->GPIOx_CRL = 0x42440000;
GPIOC->GPIOx_CRH = 0x44424442;
GPIOC->GPIOx_ODR = PORTC_OUTPUTS;
/*********************************************************
* Configure DMA channel 1 to transfer from ADC to memory
*********************************************************/
DMA->DMA_CPAR1 = ADC1_DR_Address; //ADC1->ADC_DR; // Peripheral base address
DMA->DMA_CMAR1 = (u32)&nADRawData[0]; // Memory base address
DMA->DMA_CNDTR1 = 6; // 6 data transfers
DMA->DMA_CCR1 = DMA_PRIHIGH | DMA_M16BIT | DMA_P16BIT | DMA_MINC; // | DMA_TCIE;
DMA->DMA_CCR1 |= DMA_EN;
/*********************************************************
* Configure ADC1 for scan mode, channels 10-13, 16, 17.
*********************************************************/
ADC1->ADC_CR1 = ADC_SCAN;
ADC1->ADC_CR2 = ADC_TSVREFE | ADC_DMA | ADC_ADON; // Temp sensor, DMA, ADC on
ADC1->ADC_SMPR1 = 0x00FC0FFF; // 239.5 cycles for each scan
ADC1->ADC_SQR1 = 0x00500000; // 6 conversions at a time
ADC1->ADC_SQR2 = 0x00000000;
ADC1->ADC_SQR3 = 0x2306B16A; // Channels 10-13, 16, 17
/********** Later, this code is executed ************/
/*********************************************************
* Start conversion and transfer to memory
*********************************************************/
DMA->DMA_CPAR1 = ADC1_DR_Address; //ADC1->ADC_DR; // Peripheral base address
DMA->DMA_CMAR1 = (u32)&nADRawData[0]; // Memory base address
DMA->DMA_CNDTR1 = 6; // 6 data transfers
ADC1->ADC_SR &= ~ADC_STRT; // Clear conversion started flag
ADC1->ADC_CR2 |= ADC_ADON; // Start group conversion
while ((ADC1->ADC_SR & ADC_EOC) == 0);
