moamind wrote on Tuesday, September 02, 2014:
I am writing an application using FreeRTOS V8.0.1 and the STM32F4 discovery board (Cortex-M4) in keil.
When powering and running a GPS reciever on USART2 after the IRQ is run no other tasks will resume. It was my understanding that with the Cortex-M4 processors no state saving functions need to be called during the ISR to preserve the system state and ISRs can be written as normal ensuring any rtos functions are *FromISR
In the code below I have an LCD initialise and display the some SD card information with another task updating the display with clock information. As soon as the gps_task runs and the chip recieves power (therefore transmitting NMEA strings) the IRQ will fire, the task run and then according to the debugger the application never leaves the gps_tasks infinite while loop (even sleeping the task doesnt help).
I do not understand what could cause the other tasks (LED flag, Update time, etc) to no longer be scheduled.
MAIN.C
:::c++
int main(void)
{
prvSetupHardware();
usartGate = xSemaphoreCreateMutex();
lcdGate = xSemaphoreCreateMutex();
sdCardGate = xSemaphoreCreateMutex();
gpsMSG = xSemaphoreCreateMutex();
supremaMSG = xSemaphoreCreateMutex();
xTaskCreate(lcd_demo, (signed char*)"lcd", 512, NULL, 2, NULL);
xTaskCreate(alert_flash, (signed char*)"lcd", 512, NULL, 1, NULL);
xTaskCreate(update_time, (signed char*)"time", 512, NULL, 1, NULL);
xTaskCreate(gps_task, (signed char*)"gps", 512, NULL,1,NULL);
/* Start the scheduler. */
vTaskStartScheduler();
for( ;; );
}
/*-----------------------------------------------------------*/
/*-----------------------------------------------------------*/
void lcd_demo(void){
char buffer[40];
int row = 4;
if(xSemaphoreTake(lcdGate, 500)){
lcd_init();
GLCD_Clear();
GLCD_TextGoTo(0,row);
row++;
GLCD_WriteText("Power On");
//Begin Boot Message
GLCD_TextGoTo(0,row);
row++;
GLCD_WriteText("BETR V3.1 ");
GLCD_TextGoTo(0,row);
row++;
row++;
GLCD_WriteText("Acme PTY LTD");
GLCD_TextGoTo(0,row);
row++;
row++;
GLCD_WriteText(" Greetings Earthlings");
GLCD_TextGoTo(0,row);
row++;
if(xSemaphoreTake (sdCardGate, 500)){
GLCD_WriteText("Read SD Card Contents");
if(!disk_initialize(0)){
GLCD_TextGoTo(0,row);
row++;
GLCD_WriteText("Disc Initialised");
if(!f_mount(0, &FatFs)){
GLCD_TextGoTo(0,row);
row++;
GLCD_WriteText("Drive Mounted");
fResult = f_opendir(&workDir, "");
if(fResult == FR_OK){
GLCD_TextGoTo(0,row);
row++;
GLCD_WriteText("Opened Directory");
fResult = f_readdir(&workDir, &info);
while(fResult == FR_OK && info.fname[0] != NULL){
snprintf(buffer, 40, "Name: %s Size: %d Bytes",info.fname, info.fsize);
row++;
GLCD_TextGoTo(0,row);
GLCD_WriteText(buffer);
fResult = f_readdir(&workDir, &info);
}}}}}
xSemaphoreGive(lcdGate);
}
vTaskDelete(NULL);
while(1){
vTaskDelay(200);
}
}
/*-----------------------------------------------------------*/
/*-----------------------------------------------------------*/
void alert_flash(void){
while(1){
//alert_red(ON);
alert_green(OFF);
vTaskDelay(50);
//alert_red(OFF);
alert_green(ON);
vTaskDelay(20);
}
}
/*-----------------------------------------------------------*/
/*-----------------------------------------------------------*/
void update_time(void){
char dateString[40];
char timeString[40];
RTC_DateTypeDef RTC_DateStructure;
RTC_TimeTypeDef RTC_TimeStruct;
while(1){
RTC_GetDate(RTC_Format_BIN, &RTC_DateStructure); //retrieve date information, consider shifting to low priority task with higher interval
RTC_GetTime(RTC_Format_BIN, &RTC_TimeStruct); //retrieve time information
//Build display strings in preperation
snprintf(dateString, 40, "Date 20%02d/%02d/%02d", RTC_DateStructure.RTC_Year, RTC_DateStructure.RTC_Month, RTC_DateStructure.RTC_Date);
snprintf(timeString, 40, "Time %02d:%02d:%02d", RTC_TimeStruct.RTC_Hours, RTC_TimeStruct.RTC_Minutes, RTC_TimeStruct.RTC_Seconds);
if(xSemaphoreTake(lcdGate, 500)){
GLCD_TextGoTo(0,1);
GLCD_WriteText(" ");
GLCD_TextGoTo(0,2);
GLCD_WriteText(" ");
GLCD_TextGoTo(0,1);
GLCD_WriteText(dateString);
GLCD_TextGoTo(0,2);
GLCD_WriteText(timeString);
xSemaphoreGive(lcdGate);
}
vTaskDelay(500);
}
}
/*-----------------------------------------------------------*/
/*-----------------------------------------------------------*/
void USART2_IRQHandler(void){
alert_red(ON);
}
void gps_task(void){
gps_init();
power_GPS(POWER_ON);
while(1){
vTaskDelay(1000);
}
}
/*-----------------------------------------------------------*/
/*-----------------------------------------------------------*/
static void prvSetupHardware( void )
{
/* Setup STM32 system (clock, PLL and Flash configuration) */
SystemInit();
/* Ensure all priority bits are assigned as preemption priority bits. */
NVIC_PriorityGroupConfig( NVIC_PriorityGroup_4 );
power_init();
alert_init();
power_LCD(POWER_ON);
print_usart_init();
App_RTC_Init();
}
gps_init
:::c++
void gps_init(void){
USART_InitTypeDef USART_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2);
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
GPIO_Init(GPIOA, &GPIO_InitStructure);
USART_InitStructure.USART_BaudRate = 4800;
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_Init(USART2, &USART_InitStructure);
/* Enable the USART Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0F;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
/* Enable USART */
USART_Cmd(USART2, ENABLE);
USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);
// receiverState = waitForStart;
// parsedMsg.msg_valid = NOT_VALID;
// lastKnowGoodPos.msg_valid = NOT_VALID;
}