Question
ADC via dma and USART
Posted on February 13, 2013 at 10:52
Hello, i am having trouble writing code on STM32F4Discovery. my goal is to get values from ADC in continuous mode and send them to USART/UART (with DMA or without)using interrupts. so i wrote a code made out of couple examples on stm std lib and internet. but it doesn't work and i don't know why. please give me some guidelines :)
Some code comments are not true because i changed things several times. ADC pin is PC2, using ADC3 peripheral, USART1 peripheral connected to PB6 ant PB7
/* Includes ------------------------------------------------------------------*/
#include ''stm32f4xx.h''
/* Private define ------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
#define ADC3_DR_ADDRESS ((uint32_t)0x4001224C)
uint8_t NbrOfDataToTransfer;
__IO uint8_t TxCounter;
__IO uint16_t ADC3ConvertedValue = 0;
__IO uint32_t ADC3ConvertedVoltage = 0;
void
ADC3_CH12_DMA_Config(
void
)
{
ADC_InitTypeDef ADC_InitStructure;
ADC_CommonInitTypeDef ADC_CommonInitStructure;
DMA_InitTypeDef DMA_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
/* Enable ADC3, DMA2 and GPIO clocks ****************************************/
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_GPIOC, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC3, ENABLE);
/* DMA2 Stream0 channel2 configuration **************************************/
DMA_InitStructure.DMA_Channel = DMA_Channel_2;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC3_DR_ADDRESS;
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&ADC3ConvertedValue;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
DMA_InitStructure.DMA_BufferSize = 1;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Disable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA2_Stream0, &DMA_InitStructure);
DMA_Cmd(DMA2_Stream0, ENABLE);
/* Configure ADC3 Channel7 pin as analog input ******************************/
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
GPIO_Init(GPIOC, &GPIO_InitStructure);
/* ADC Common Init **********************************************************/
ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;
ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div2;
ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;
ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
ADC_CommonInit(&ADC_CommonInitStructure);
/* ADC3 Init ****************************************************************/
ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
ADC_InitStructure.ADC_ScanConvMode = DISABLE;
ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T1_CC1;
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_NbrOfConversion = 1;
ADC_Init(ADC3, &ADC_InitStructure);
/* ADC3 regular channel7 configuration *************************************/
ADC_RegularChannelConfig(ADC3, ADC_Channel_12, 1, ADC_SampleTime_3Cycles);
/* Enable DMA request after last transfer (Single-ADC mode) */
ADC_DMARequestAfterLastTransferCmd(ADC3, ENABLE);
/* Enable ADC3 DMA */
ADC_DMACmd(ADC3, ENABLE);
/* Enable ADC3 */
ADC_Cmd(ADC3, ENABLE);
}
void
init_USART1(uint32_t baudrate)
{
USART_InitTypeDef USART_InitStruct;
GPIO_InitTypeDef GPIO_InitStruct;
// this is for the GPIO pins used as TX and RX
/* enable APB2 peripheral clock for USART1
* note that only USART1 and USART6 are connected to APB2
* the other USARTs are connected to APB1
*/
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
/* enable the peripheral clock for the pins used by
* USART1, PB6 for TX and PB7 for RX
*/
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
/* This sequence sets up the TX and RX pins
* so they work correctly with the USART1 peripheral
*/
GPIO_InitStruct.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
// Pins 6 (TX) and 7 (RX) are used
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
// the pins are configured as alternate function so the USART peripheral has access to them
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
// this defines the IO speed and has nothing to do with the baudrate!
GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
// this defines the output type as push pull mode (as opposed to open drain)
GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
// this activates the pullup resistors on the IO pins
GPIO_Init(GPIOB, &GPIO_InitStruct);
// now all the values are passed to the GPIO_Init() function which sets the GPIO registers
/* The RX and TX pins are now connected to their AF
* so that the USART1 can take over control of the
* pins
*/
GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_USART1);
//
GPIO_PinAFConfig(GPIOB, GPIO_PinSource7, GPIO_AF_USART1);
/* Now the USART_InitStruct is used to define the
* properties of USART1
*/
USART_InitStruct.USART_BaudRate = baudrate;
USART_InitStruct.USART_WordLength = USART_WordLength_8b;
USART_InitStruct.USART_StopBits = USART_StopBits_1;
USART_InitStruct.USART_Parity = USART_Parity_No;
USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStruct.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
USART_Init(USART1, &USART_InitStruct);
/* Enable the EVAL_USART1 Transmit interrupt: this interrupt is generated when the
EVAL_USART1 transmit data register is empty */
USART_ITConfig(USART1, USART_IT_TXE, ENABLE);
USART_Cmd(USART1, ENABLE);
// finally this enables the complete USART1 peripheral
}
void
NVIC_Config(
void
)
{
NVIC_InitTypeDef NVIC_InitStructure;
/* Enable the USARTx Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
int
main(
void
)
{
init_USART1(115200);
NVIC_Config();
ADC3_CH12_DMA_Config();
ADC_SoftwareStartConv(ADC3);
while
(1)
{
ADC3ConvertedVoltage = ADC3ConvertedValue *3300/0xFFF;
USART_SendData(USART1, ADC3ConvertedVoltage);
}
}
// this is the interrupt request handler (IRQ) for ALL USART1 interrupts
void
USART1_IRQHandler(
void
)
{
/* Wait until EVAL_USART1 send the TxBuffer */
while
(TxCounter < NbrOfDataToTransfer)
{}
/* The software must wait until TC=1. The TC flag remains cleared during all data
transfers and it is set by hardware at the last frame’s end of transmission*/
while
(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET)
{}
} 