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R2671/Firmware/src/drivers/uart.c
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uart.c
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#include "uart.h"
#include "../lib/utils.h"
#include "../communication.h" // TODO: REMOVE. DEBUG ONLY.
#define UART_RX_DMA DMA1_Stream5
#define UART_RX_DMA_CHANNEL DMA_Channel_4
#define UART_TX_DMA DMA1_Stream6
#define UART_TX_DMA_CHANNEL DMA_Channel_4
#define UART_TX_BUFFER_SIZE 512
#define UART_RX_BUFFER_SIZE 512
#define UART_USER_RX_QUEUE_SIZE 512
uint8_t uart_txBuffer[2][UART_TX_BUFFER_SIZE];
uint8_t uart_currentTxBufferToWriteTo;
uint16_t uart_txBufferIndex;
uint16_t uart_nBytesToTransferDma;
uint8_t uart_rxBuffer[UART_RX_BUFFER_SIZE];
uint8_t const * uart_rxBuffTail;
uint8_t uart_userRxQueue[UART_USER_RX_QUEUE_SIZE];
cb_CircularBuffer uart_rxQueue;
#define UART_DMA_TX_IS_BUSY (DMA_GetCmdStatus(UART_TX_DMA) == ENABLE && DMA_GetCurrDataCounter(UART_TX_DMA) > 0)
/**
* @brief Initializes the UART module.
*/
void uart_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
USART_InitTypeDef USART_InitStruct;
DMA_InitTypeDef DMA_InitStruct;
// Enable UART and DMA peripherals clocks.
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);
// Setup GPIOs as UART pins.
GPIO_InitStruct.GPIO_Pin = USART_TX_Pin;
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(USART_TX_Port, &GPIO_InitStruct);
GPIO_PinAFConfig(USART_TX_Port, USART_TX_PinSource, GPIO_AF_USART2);
GPIO_InitStruct.GPIO_Pin = USART_RX_Pin;
GPIO_Init(USART_RX_Port, &GPIO_InitStruct);
GPIO_PinAFConfig(USART_RX_Port, USART_RX_PinSource, GPIO_AF_USART2);
// Setup the UART peripheral.
USART_InitStruct.USART_BaudRate = UART_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_Tx | USART_Mode_Rx;
USART_Init(USART_PC_COMM, &USART_InitStruct);
USART_Cmd(USART_PC_COMM, ENABLE);
// Setup the DMA for RX.
DMA_DeInit(UART_RX_DMA);
DMA_InitStruct.DMA_Channel = UART_RX_DMA_CHANNEL;
DMA_InitStruct.DMA_PeripheralBaseAddr = (uint32_t)&USART2->DR;
DMA_InitStruct.DMA_Memory0BaseAddr = (uint32_t)&uart_rxBuffer[0];
DMA_InitStruct.DMA_DIR = DMA_DIR_PeripheralToMemory;
DMA_InitStruct.DMA_BufferSize = UART_RX_BUFFER_SIZE;
DMA_InitStruct.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStruct.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStruct.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStruct.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStruct.DMA_Mode = DMA_Mode_Circular;
DMA_InitStruct.DMA_Priority = DMA_Priority_Medium;
DMA_InitStruct.DMA_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStruct.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStruct.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(UART_RX_DMA, &DMA_InitStruct);
USART_DMACmd(USART_PC_COMM, USART_DMAReq_Rx | USART_DMAReq_Tx, ENABLE);
DMA_ITConfig(UART_RX_DMA, DMA_IT_TC, ENABLE);
DMA_Cmd(UART_RX_DMA, ENABLE);
uart_rxBuffTail = &uart_rxBuffer[0];
// Setup the DMA for TX.
DMA_DeInit(UART_TX_DMA);
DMA_InitStruct.DMA_Channel = UART_TX_DMA_CHANNEL;
DMA_InitStruct.DMA_PeripheralBaseAddr = (uint32_t)&USART2->DR;
DMA_InitStruct.DMA_Memory0BaseAddr = (uint32_t)&uart_txBuffer[0][0];
DMA_InitStruct.DMA_DIR = DMA_DIR_MemoryToPeripheral;
DMA_InitStruct.DMA_BufferSize = UART_TX_BUFFER_SIZE;
DMA_InitStruct.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStruct.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStruct.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStruct.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStruct.DMA_Mode = DMA_Mode_Normal;
DMA_InitStruct.DMA_Priority = DMA_Priority_Medium;
DMA_InitStruct.DMA_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStruct.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStruct.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(UART_TX_DMA, &DMA_InitStruct);
USART_DMACmd(USART_PC_COMM, USART_DMAReq_Rx | USART_DMAReq_Tx, ENABLE);
DMA_ITConfig(UART_TX_DMA, DMA_IT_TC, ENABLE);
//DMA_Cmd(UART_TX_DMA, ENABLE);
// Initialize the RX circular buffer.
cb_Init(&uart_rxQueue, uart_userRxQueue, UART_USER_RX_QUEUE_SIZE);
// Initialize the variables for the UART TX.
uart_currentTxBufferToWriteTo = 0;
uart_txBufferIndex = 0;
uart_nBytesToTransferDma = 0;
}
/**
* @brief Copies the received bytes into the user-accessible queue.
* Reads all the available bytes in the DMA RX buffer, and copies them to the
* user-accessible queue.
* @remark This function must called often, otherwise the DMA RX buffer may be
* full.
*/
void uart_Step(void)
{
// Get the location of the location currently pointed by the DMA.
uint8_t const * head = uart_rxBuffer + UART_RX_BUFFER_SIZE
- DMA_GetCurrDataCounter(UART_RX_DMA);
// Even if the STM32F4 reference manual (RM0090) states that the NDTR
// register is decremented after the transfer, this is not the case.
// So we wait a few cycles to be sure that the DMA actually performed the
// transfer.
utils_DelayUs(1);
// RX: add the received bytes into the user queue.
while(uart_rxBuffTail != head)
{
uint8_t b = *uart_rxBuffTail;
cb_Push(&uart_rxQueue, b);
uart_rxBuffTail++;
if(uart_rxBuffTail >= uart_rxBuffer + UART_RX_BUFFER_SIZE)
uart_rxBuffTail -= UART_RX_BUFFER_SIZE;
}
}
/**
* @brief Gets the user-accessible queue of the received bytes.
* @return the address of the queue.
*/
cb_CircularBuffer* uart_GetRxQueue(void)
{
return &uart_rxQueue;
}
/**
* @brief Starts the DMA transfer to send bytes to UART peripheral.
*/
void uart_StartDma(void)
{
DMA_InitTypeDef DMA_InitStruct;
//
uart_nBytesToTransferDma = uart_txBufferIndex;
uart_currentTxBufferToWriteTo = !uart_currentTxBufferToWriteTo;
uart_txBufferIndex = 0;
// Start the DMA transfer.
DMA_DeInit(UART_TX_DMA);
DMA_InitStruct.DMA_Channel = UART_TX_DMA_CHANNEL;
DMA_InitStruct.DMA_PeripheralBaseAddr = (uint32_t)&USART2->DR;
DMA_InitStruct.DMA_Memory0BaseAddr = (uint32_t)&uart_txBuffer[!uart_currentTxBufferToWriteTo][0];
DMA_InitStruct.DMA_DIR = DMA_DIR_MemoryToPeripheral;
DMA_InitStruct.DMA_BufferSize = uart_nBytesToTransferDma;
DMA_InitStruct.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStruct.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStruct.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStruct.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStruct.DMA_Mode = DMA_Mode_Normal;
DMA_InitStruct.DMA_Priority = DMA_Priority_Medium;
DMA_InitStruct.DMA_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStruct.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStruct.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(UART_TX_DMA, &DMA_InitStruct);
DMA_Cmd(UART_TX_DMA, ENABLE);
}
/**
* @brief Asynchronously sends the given byte through the UART bus.
* @param data the data byte to send.
*/
void uart_SendByteAsync(uint8_t data)
{
// Check that it is possible to write in the current buffer.
if(uart_txBufferIndex >= UART_TX_BUFFER_SIZE)
{
// If the DMA is idle, switch to the other buffer.
if(UART_DMA_TX_IS_BUSY)
{
utils_TrapCpu(); // Error, can't write anywhere!
return;
}
else
uart_StartDma();
}
// Write the byte in the buffer.
uart_txBuffer[uart_currentTxBufferToWriteTo][uart_txBufferIndex] = data;
uart_txBufferIndex++;
// If the buffer is full, start the DMA transfer.
if(uart_txBufferIndex == UART_TX_BUFFER_SIZE)
uart_StartDma();
}
/**
* @brief Asynchronously sends the given bytes through the UART bus.
* @param data pointer to the data bytes array to send.
* @param length number of bytes to send (array size).
* @remark The bytes may not be send immediately, they are stored temporarily in
* an intermediate buffer that the DMA will copy to UART peripheral, when it is
* full. Call uart_FlushTx() to start the DMA transfer immediately.
*/
void uart_SendBytesAsync(uint8_t *data, int length)
{
while(length > 0)
{
uint16_t nBytesToWriteInBuf;
// Check that it is possible to write in the current buffer.
if(uart_txBufferIndex >= UART_TX_BUFFER_SIZE)
{
// If the DMA is idle, switch to the other buffer.
if(UART_DMA_TX_IS_BUSY)
{
utils_TrapCpu(); // Error, can't write anywhere!
return;
}
else
uart_StartDma();
}
// Write as many bytes as possible in the current buffer.
nBytesToWriteInBuf = UART_TX_BUFFER_SIZE - uart_txBufferIndex;
if(nBytesToWriteInBuf > length)
nBytesToWriteInBuf = length;
memcpy(&uart_txBuffer[uart_currentTxBufferToWriteTo][uart_txBufferIndex],
data, nBytesToWriteInBuf);
uart_txBufferIndex += nBytesToWriteInBuf;
data += nBytesToWriteInBuf;
length -= nBytesToWriteInBuf;
// If the buffer is full, start the DMA transfer.
if(uart_txBufferIndex == UART_TX_BUFFER_SIZE)
uart_StartDma();
}
}
/**
* @brief Start the DMA to send the bytes waiting in the intermediate buffer.
*/
void uart_FlushTx(void)
{
if(uart_txBufferIndex > 0 && !UART_DMA_TX_IS_BUSY)
uart_StartDma();
}
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