我一直在尝试在 EFM32 Starter 类型上设置一个 uart，现在我可以将 EFM32 Starter 套件板中的字符发送到计算机，但是当我尝试使用示例从计算机接收时，我的中断被调用一次，但我得到的数据是 0x0 ，然后在第一个字符之后我没有再次收到中断。
我修改了可以在 silab 网站上找到的应用笔记软件的代码：USART/UART 异步模式应用笔记软件
我也将代码添加到这个问题中。有人遇到过这种情况么？我一定是在做傻事。
我检查了调试器中的 RXDATA 寄存器，即使我按下键盘上的“a”字符，它仍然显示 0。此外，中断只触发一次，rxdata 为 0，然后我再也没有收到中断。
提前致谢。
/******************************************************************************
* @file main.c
* @brief USART/UART Asynchronous mode Application Note software example
* @author Silicon Labs
* @version 1.03
******************************************************************************
* @section License
* <b>(C) Copyright 2014 Silicon Labs, http://www.silabs.com</b>
*******************************************************************************
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*
* DISCLAIMER OF WARRANTY/LIMITATION OF REMEDIES: Silicon Labs has no
* obligation to support this Software. Silicon Labs is providing the
* Software "AS IS", with no express or implied warranties of any kind,
* including, but not limited to, any implied warranties of merchantability
* or fitness for any particular purpose or warranties against infringement
* of any proprietary rights of a third party.
*
* Silicon Labs will not be liable for any consequential, incidental, or
* special damages, or any other relief, or for any claim by any third party,
* arising from your use of this Software.
*
******************************************************************************/
#include <stdint.h>
#include "em_device.h"
#include "em_chip.h"
#include "em_emu.h"
#include "em_cmu.h"
#include "em_gpio.h"
#include "em_usart.h"
#include "bsp.h"
/* Function prototypes */
void uartSetup(void);
void cmuSetup(void);
void uartPutData(uint8_t * dataPtr, uint32_t dataLen);
uint32_t uartGetData(uint8_t * dataPtr, uint32_t dataLen);
void uartPutChar(uint8_t charPtr);
uint8_t uartGetChar(void);
/* Declare some strings */
const char welcomeString[] = "EFM32 RS-232 - Please press a key\r\n";
const char overflowString[] = "\n---RX OVERFLOW---\n";
const uint32_t welLen = sizeof(welcomeString) - 1;
const uint32_t ofsLen = sizeof(overflowString) - 1;
/* Define termination character */
#define TERMINATION_CHAR '.'
/* Declare a circular buffer structure to use for Rx and Tx queues */
#define BUFFERSIZE 256
volatile struct circularBuffer
{
uint8_t data[BUFFERSIZE]; /* data buffer */
uint32_t rdI; /* read index */
uint32_t wrI; /* write index */
uint32_t pendingBytes; /* count of how many bytes are not yet handled */
bool overflow; /* buffer overflow indicator */
} rxBuf, txBuf = { {0}, 0, 0, 0, false };
/* Setup UART1 in async mode for RS232*/
static USART_TypeDef * uart = USART1;
static USART_InitAsync_TypeDef uartInit = USART_INITASYNC_DEFAULT;
/******************************************************************************
* @brief Main function
*
*****************************************************************************/
int main(void)
{
/* Initialize chip - handle erratas */
CHIP_Init( );
/* Initialize clocks and oscillators */
cmuSetup( );
/* Initialize UART peripheral */
uartSetup( );
/* Initialize Development Kit in EBI mode */
// BSP_Init(BSP_INIT_DEFAULT);
/* Enable RS-232 transceiver on Development Kit */
//BSP_PeripheralAccess(BSP_RS232_UART, true);
/* When DVK is configured, and no more DVK access is needed, the interface can safely be disabled to save current */
//BSP_Disable();
/* Write welcome message to UART */
uartPutData((uint8_t*) welcomeString, welLen);
/* Eternal while loop
* CPU will sleep during Rx and Tx. When a byte is transmitted, an interrupt
* wakes the CPU which copies the next byte in the txBuf queue to the
* UART TXDATA register.
*
* When the predefined termiation character is received, the all pending
* data in rxBuf is copied to txBuf and echoed back on the UART */
while (1)
{
/* Wait in EM1 while UART transmits */
EMU_EnterEM1();
/* Check if RX buffer has overflowed */
if (rxBuf.overflow)
{
rxBuf.overflow = false;
uartPutData((uint8_t*) overflowString, ofsLen);
}
/* Check if termination character is received */
if (rxBuf.data[(rxBuf.wrI - 1) % BUFFERSIZE] == TERMINATION_CHAR)
{
/* Copy received data to UART transmit queue */
uint8_t tmpBuf[BUFFERSIZE];
int len = uartGetData(tmpBuf, 0);
uartPutData(tmpBuf, len);
}
}
}
/******************************************************************************
* @brief uartSetup function
*
******************************************************************************/
void uartSetup(void)
{
/* Enable clock for GPIO module (required for pin configuration) */
CMU_ClockEnable(cmuClock_GPIO, true);
/* Configure GPIO pins */
GPIO_PinModeSet(gpioPortC, 0, gpioModePushPull, 1);
GPIO_PinModeSet(gpioPortC, 1, gpioModeInput, 0);
/* Prepare struct for initializing UART in asynchronous mode*/
uartInit.enable = usartDisable; /* Don't enable UART upon intialization */
uartInit.refFreq = 0; /* Provide information on reference frequency. When set to 0, the reference frequency is */
uartInit.baudrate = 115200; /* Baud rate */
uartInit.oversampling = usartOVS16; /* Oversampling. Range is 4x, 6x, 8x or 16x */
uartInit.databits = usartDatabits8; /* Number of data bits. Range is 4 to 10 */
uartInit.parity = usartNoParity; /* Parity mode */
uartInit.stopbits = usartStopbits1; /* Number of stop bits. Range is 0 to 2 */
// uartInit.mvdis = false; /* Disable majority voting */
// uartInit.prsRxEnable = false; /* Enable USART Rx via Peripheral Reflex System */
// uartInit.prsRxCh = usartPrsRxCh0; /* Select PRS channel if enabled */
/* Initialize USART with uartInit struct */
USART_InitAsync(uart, &uartInit);
/* Prepare UART Rx and Tx interrupts */
USART_IntClear(uart, _UART_IFC_MASK);
USART_IntEnable(uart, UART_IEN_RXDATAV);
NVIC_ClearPendingIRQ(USART1_RX_IRQn);
NVIC_ClearPendingIRQ(USART1_TX_IRQn);
NVIC_EnableIRQ(USART1_RX_IRQn);
NVIC_EnableIRQ(USART1_TX_IRQn);
/* Enable I/O pins at UART1 location #2 */
uart->ROUTE = UART_ROUTE_RXPEN | UART_ROUTE_TXPEN | UART_ROUTE_LOCATION_LOC0;
/* Enable UART */
USART_Enable(uart, usartEnable);
}
/******************************************************************************
* @brief uartGetChar function
*
* Note that if there are no pending characters in the receive buffer, this
* function will hang until a character is received.
*
*****************************************************************************/
uint8_t uartGetChar( )
{
uint8_t ch;
/* Check if there is a byte that is ready to be fetched. If no byte is ready, wait for incoming data */
if (rxBuf.pendingBytes < 1)
{
while (rxBuf.pendingBytes < 1) ;
}
/* Copy data from buffer */
ch = rxBuf.data[rxBuf.rdI];
rxBuf.rdI = (rxBuf.rdI + 1) % BUFFERSIZE;
/* Decrement pending byte counter */
rxBuf.pendingBytes--;
return ch;
}
/******************************************************************************
* @brief uartPutChar function
*
*****************************************************************************/
void uartPutChar(uint8_t ch)
{
/* Check if Tx queue has room for new data */
if ((txBuf.pendingBytes + 1) > BUFFERSIZE)
{
/* Wait until there is room in queue */
while ((txBuf.pendingBytes + 1) > BUFFERSIZE) ;
}
/* Copy ch into txBuffer */
txBuf.data[txBuf.wrI] = ch;
txBuf.wrI = (txBuf.wrI + 1) % BUFFERSIZE;
/* Increment pending byte counter */
txBuf.pendingBytes++;
/* Enable interrupt on USART TX Buffer*/
USART_IntEnable(uart, UART_IEN_TXBL);
}
/******************************************************************************
* @brief uartPutData function
*
*****************************************************************************/
void uartPutData(uint8_t * dataPtr, uint32_t dataLen)
{
uint32_t i = 0;
/* Check if buffer is large enough for data */
if (dataLen > BUFFERSIZE)
{
/* Buffer can never fit the requested amount of data */
return;
}
/* Check if buffer has room for new data */
if ((txBuf.pendingBytes + dataLen) > BUFFERSIZE)
{
/* Wait until room */
while ((txBuf.pendingBytes + dataLen) > BUFFERSIZE) ;
}
/* Fill dataPtr[0:dataLen-1] into txBuffer */
while (i < dataLen)
{
txBuf.data[txBuf.wrI] = *(dataPtr + i);
txBuf.wrI = (txBuf.wrI + 1) % BUFFERSIZE;
i++;
}
/* Increment pending byte counter */
txBuf.pendingBytes += dataLen;
/* Enable interrupt on USART TX Buffer*/
USART_IntEnable(uart, UART_IEN_TXBL);
}
/******************************************************************************
* @brief uartGetData function
*
*****************************************************************************/
uint32_t uartGetData(uint8_t * dataPtr, uint32_t dataLen)
{
uint32_t i = 0;
/* Wait until the requested number of bytes are available */
if (rxBuf.pendingBytes < dataLen)
{
while (rxBuf.pendingBytes < dataLen) ;
}
if (dataLen == 0)
{
dataLen = rxBuf.pendingBytes;
}
/* Copy data from Rx buffer to dataPtr */
while (i < dataLen)
{
*(dataPtr + i) = rxBuf.data[rxBuf.rdI];
rxBuf.rdI = (rxBuf.rdI + 1) % BUFFERSIZE;
i++;
}
/* Decrement pending byte counter */
rxBuf.pendingBytes -= dataLen;
return i;
}
/***************************************************************************//**
* @brief Set up Clock Management Unit
******************************************************************************/
void cmuSetup(void)
{
/* Start HFXO and wait until it is stable */
/* CMU_OscillatorEnable( cmuOsc_HFXO, true, true); */
/* Select HFXO as clock source for HFCLK */
/* CMU_ClockSelectSet(cmuClock_HF, cmuSelect_HFXO ); */
/* Disable HFRCO */
/* CMU_OscillatorEnable( cmuOsc_HFRCO, false, false ); */
/* Enable clock for HF peripherals */
CMU_ClockEnable(cmuClock_HFPER, true);
/* Enable clock for USART module */
CMU_ClockEnable(cmuClock_USART1, true);
}
/**************************************************************************//**
* @brief UART1 RX IRQ Handler
*
* Set up the interrupt prior to use
*
* Note that this function handles overflows in a very simple way.
*
*****************************************************************************/
void USART1_RX_IRQHandler(void)
{
/* Check for RX data valid interrupt */
if (uart->IF & UART_IF_RXDATAV)
{
/* Copy data into RX Buffer */
uint8_t rxData = USART_Rx(uart);
rxBuf.data[rxBuf.wrI] = rxData;
rxBuf.wrI = (rxBuf.wrI + 1) % BUFFERSIZE;
rxBuf.pendingBytes++;
/* Flag Rx overflow */
if (rxBuf.pendingBytes > BUFFERSIZE)
{
rxBuf.overflow = true;
}
}
}
/**************************************************************************//**
* @brief UART1 TX IRQ Handler
*
* Set up the interrupt prior to use
*
*****************************************************************************/
void USART1_TX_IRQHandler(void)
{
/* Check TX buffer level status */
if (uart->IF & UART_IF_TXBL)
{
if (txBuf.pendingBytes > 0)
{
/* Transmit pending character */
USART_Tx(uart, txBuf.data[txBuf.rdI]);
txBuf.rdI = (txBuf.rdI + 1) % BUFFERSIZE;
txBuf.pendingBytes--;
}
/* Disable Tx interrupt if no more bytes in queue */
if (txBuf.pendingBytes == 0)
{
USART_IntDisable(uart, UART_IEN_TXBL);
}
}
}