2017-01-27 11:06 AM
I have been thrust into a situation where I realize I am in over my head. Eventually I think I will figure it out but could use a leg up with this STM32F437 device. I know little about it and especially it’s dma.
The project I have been assigned to uses DMA to communicate with the debug port UART8.
The DMAChannel is set to DMA_Channel_5, and from the table transmission for uart 8 is set for stream 0 and rx is stream6.
We are using Micrium uC/OS-III and in the interrupt vector table I see no interrupts setup for the UART but I do see an RxISR and a TxISR. From this should I assume that there is some smart linkage that lets the DMA know there are characters available at the UART.
AT startup the welcome banner is splashed. However when a character is entered to start the login process the system hangs up. Looking at the registers we see a transmit transfer error bit that will not clear.
My co-worker suspects that maybe it is due to dma transmit and receive happening at the same time but the documentation does not prohibit this as far as I know. So could this be a problem?
Thanks,
jh
2017-01-27 01:40 PM
Uses DMA1, UART8_TX Stream 0 Channel 5, UART8_RX Stream 6 Channel 5
You have to program the DMA controller to initiate any transfer. RX could be in circular mode, interrupting via the DMA HT/TC interrupts.
RX and TX can occur concurrently. You'd need to make sure buffers are not transient (local/auto), and one TX completes before starting another.
What are you looking for? Code that demonstrates DMA functionality? Using what pins?
2017-01-28 10:31 AM
Thanks for the post.
Yes, I would definitely like some good DMA/UART example code. The pins are UART8, PE0 & PE1.
Thanks,
jh
2017-01-31 12:22 PM
Quick blind UART8 TX example
// STM32 UART8 DMA TX (Tx PE.1, Rx PE.0) STM32F437 - sourcer32@gmail.com
#include 'stm32f4xx.h'
/**************************************************************************************/
void RCC_Configuration(void)
{
/* --------------------------- System Clocks Configuration -----------------*/
/* UART8 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_UART8, ENABLE);
/* GPIOE clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE, ENABLE);
/* DMA1 clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);
}
/**************************************************************************************/
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/*-------------------------- GPIO Configuration ----------------------------*/
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOE, &GPIO_InitStructure);
/* Connect USART pins to AF */
GPIO_PinAFConfig(GPIOE, GPIO_PinSource0, GPIO_AF_UART8); // UART8_R
X GPIO_PinAFConfig(GPIOE, GPIO_PinSource1, GPIO_AF_UART8); // UART8_T
X}
/**************************************************************************************/
void UART8_Configuration(void)
{
USART_InitTypeDef USART_InitStructure;
/* USARTx configuration ------------------------------------------------------*/
/* USARTx configured as follow:
- BaudRate = 115200 baud
- Word Length = 8 Bits
- One Stop Bit
- No parity
- Hardware flow control disabled (RTS and CTS signals)
- Receive and transmit enabled
*/
USART_InitStructure.USART_BaudRate = 115200;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_Parity = USART_Parity_No;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
USART_Init(UART8, &USART_InitStructure);
USART_Cmd(UART8, ENABLE);
}
/**************************************************************************************/
char Buffer[] = 'The quick brown fox jumps over the lazy dog
';
void DMA_Configuration(void)
{
DMA_InitTypeDef DMA_InitStructure;
DMA_DeInit(DMA1_Stream0);
DMA_InitStructure.DMA_Channel = DMA_Channel_5;
DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral; // Transmit
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)Buffer;
DMA_InitStructure.DMA_BufferSize = (uint16_t)sizeof(Buffer) - 1;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&UART8->DR;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Enable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA1_Stream0, &DMA_InitStructure);
/* Enable the USART Tx DMA request */
USART_DMACmd(UART8, USART_DMAReq_Tx, ENABLE);
/* Enable DMA Stream Transfer Complete interrupt */
DMA_ITConfig(DMA1_Stream0, DMA_IT_TC, ENABLE);
/* Enable the DMA RX Stream */
DMA_Cmd(DMA1_Stream0, ENABLE);
}
/**************************************************************************************/
void DMA1_Stream0_IRQHandler(void)
{
/* Test on DMA Stream Transfer Complete interrupt */
if (DMA_GetITStatus(DMA1_Stream0, DMA_IT_TCIF0))
{
/* Clear DMA Stream Transfer Complete interrupt pending bit */
DMA_ClearITPendingBit(DMA1_Stream0, DMA_IT_TCIF0);
}
}
/**************************************************************************************/
void NVIC_Configuration(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
/* Configure the Priority Group to 2 bits */
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
/* Enable the UART8 TX DMA Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = DMA1_Stream0_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
/**************************************************************************************/
int main(void)
{
RCC_Configuration();
NVIC_Configuration();
GPIO_Configuration();
UART8_Configuration();
DMA_Configuration();
while(1); // Don't want to exit
}
/**************************************************************************************/
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t* file, uint32_t line)
{
/* User can add his own implementation to report the file name and line number,
ex: printf('Wrong parameters value: file %s on line %d
', file, line) */
/* Infinite loop */
while (1)
{
}
}
#endif
/**************************************************************************************/
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