Communication betwen STM32 microcontroller and SIM20 module with USART device - c

Question

I'm trying to make a STM32f1 microcontroller communicate with a SIM20 module.
I hope that all hardware setting were well made.
Speaking of the software, my C program is composed of the following components:
RCC configuration
GPIO configuration
USART configuration
Send of the string "AT+SRDFIRM"
Storing the received buffer in a file "test.txt"
Turn on the LED3
However nothing is received from the SIM20. Nothing was stored in the file and LED3 doesn't turn on.
My C code is the following:
/* Includes ------------------------------------------------------------------*/
#include "stm32f10x.h"
#include "stm32_eval.h"
#include <stdio.h>
#include <stdlib.h>
/* Private typedef -----------------------------------------------------------*/
typedef enum { FAILED = 0, PASSED = !FAILED} TestStatus;
/* Private define ------------------------------------------------------------*/
#define USARTy USART1
#define USARTy_GPIO GPIOA /* PORT name*/
#define USARTy_CLK RCC_APB2Periph_USART1
#define USARTy_GPIO_CLK RCC_APB2Periph_GPIOA
#define USARTy_RxPin GPIO_Pin_10/* pin Rx name*/
#define USARTy_TxPin GPIO_Pin_9 /* pin Tx name*/
#define USARTz USART2
#define USARTz_GPIO GPIOA/* PORT name*/
#define USARTz_CLK RCC_APB1Periph_USART2
#define USARTz_GPIO_CLK RCC_APB2Periph_GPIOA
#define USARTz_RxPin GPIO_Pin_3/* pin Rx name*/
#define USARTz_TxPin GPIO_Pin_2/* pin Tx name*/
#define TxBufferSize (countof(TxBuffer))
/* Private macro -------------------------------------------------------------*/
#define countof(a) (sizeof(a) / sizeof(*(a)))
/* Private variables ---------------------------------------------------------*/
USART_InitTypeDef USART_InitStructure;
uint8_t TxBuffer[] = "AT+SRDFIRM";
uint8_t RxBuffer[TxBufferSize];
__IO uint8_t TxConteur = 0, RxConteur = 0;
uint8_t Bin[16];
/* Private function prototypes -----------------------------------------------*/
void RCC_Configuration(void);
void GPIO_Configuration(void);
void Delay(__IO uint32_t);
TestStatus Buffercmp(uint8_t* pBuffer1, uint8_t* pBuffer2, uint16_t BufferLength);
__IO uint8_t index = 0;
volatile TestStatus TransferStatus = FAILED;
GPIO_InitTypeDef GPIO_InitStructure;
int main(void)
{
STM_EVAL_LEDInit(LED1);
STM_EVAL_LEDInit(LED2);
STM_EVAL_LEDInit(LED3);
STM_EVAL_LEDInit(LED4);
int i;
/*TxBuffer[0] = 'B';
RxBuffer[0] ='\0';*/
/* System Clocks Configuration */
RCC_Configuration();
/* Configure the GPIO ports */
GPIO_Configuration();
USART_InitStructure.USART_BaudRate = 115200; // configuration vitesse
USART_InitStructure.USART_WordLength = USART_WordLength_8b; // configuration longueur mot
USART_InitStructure.USART_StopBits = USART_StopBits_1; // bit de stop
USART_InitStructure.USART_Parity = USART_Parity_No; // bit de parite
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None; // hardware control
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx; // half duplex
/* Configure USARTy */
USART_Init(USART1,&USART_InitStructure);
/* Enable the USARTy */
USART_Cmd(USART1,ENABLE);
uint16_t reciv;
/*********************************************************/
FILE* fichier = NULL;
fichier = fopen("test.txt", "w");
while(TxConteur < TxBufferSize)
{
/* Send one byte from USARTy to USARTz */
USART_SendData(USARTy, TxBuffer[TxConteur++]);
}
/* Loop until USARTy DR register is empty */
while(USART_GetFlagStatus(USART1, USART_FLAG_RXNE) == RESET);
while(TxConteur < TxBufferSize)
{
RxBuffer[RxConteur] = USART_ReceiveData(USARTy) & 0xFF;
RxConteur++;
}
fprintf(fichier,"%s","RxBuffer");
fclose(fichier); // On ferme le fichier qui a été ouvert
TransferStatus = Buffercmp(TxBuffer, RxBuffer, TxBufferSize);
STM_EVAL_LEDOn(LED3);
while (1)
{
}
}
void RCC_Configuration(void)
{
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA , ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 , ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC , ENABLE);
}
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure1,GPIO_InitStructure2;
/* Configure USARTy Rx as input floating */
GPIO_InitStructure1.GPIO_Pin =GPIO_Pin_10;
GPIO_InitStructure1.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure1.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure1);
/* Configure USARTy Tx as alternate function push-pull */
GPIO_InitStructure2.GPIO_Pin =GPIO_Pin_9;
GPIO_InitStructure2.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure2.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOA, &GPIO_InitStructure2);
}
TestStatus Buffercmp(uint8_t* pBuffer1, uint8_t* pBuffer2, uint16_t BufferLength)
{
while(BufferLength--)
{
if(*pBuffer1 != *pBuffer2)
{
return FAILED;
}
pBuffer1++;
pBuffer2++;
}
return PASSED;
}
#H2CO3 : this is the part of the program which contain the problem:
while(TxConteur < TxBufferSize-1)
{
/* Send one byte from USARTy to USARTz */
USART_SendData(USARTy, TxBuffer[TxConteur++]);
while(USART_GetFlagStatus(USART1, USART_FLAG_IDLE) == RESET);
}
RxConteur=0;
/* Store the received byte in RxBuffer */
while(RxConteur < TxBufferSize-1)
{
RxBuffer[RxConteur] = USART_ReceiveData(USARTy) & 0xFF;
RxConteur++;
}

Answer 1

Some things to look at:
Is the UART in reset?
I don't recall off-hand if the STM32 leaves the UARTs in reset by default. You enable the clock, but do not explicitly take it out of reset. If it is still in reset, then when you spin waiting for the RXNE flag to set, it may always read as reset. This would stop execution and you wouldn't reach the LED enable.
Do USART_SendData and USART_ReceiveData check the status of the data register?
If these functions don't check the state of the data register, then your transmit is likely not coming out properly. It takes 80 microseconds to transmit a character at 115200. The first write to the DR would be loaded into the shift register quickly, and the second write to the DR would be held, but unless the DR status is checked in USART_SendData further attempts to send would stomp on the previous bytes loaded. The end result transmitted would likely come out on the serial line as AM.
Similarly, USART_ReceiveData would likely fill up the receive buffer with repeats of the same byte until the next byte comes in (though the STM32 may clear the DR after the value is read).
Files. What compiler and runtime are you using?
Since this is your main() function, we can see what is being initialized at startup. I don't see any initialization of a filesystem. It could be happening before main, depending on the runtime. What tool are you using to build this and does it support file access? I know IAR's runtime supports standard file calls, but by default they will return failure unless you implement low level functions. You aren't checking that the file opened successfully, and the write with fprintf may be crashing.
Ensure that your runtime supports file access and does something meaningful with the calls, and add error checking to your file calls.