MQX releasing a semaphore in a interrupt handler

viveksrinivasan — Tue, 25 Aug 2015 01:50:41 GMT

Hello everyone,

I'm using KSDK_1.2.0 with twrk65f180m.

Initially I tested the uart_edma_blocking example with bare metal and it worked fine.

Then I copied the example under a thread in an application which uses MQX operating system.

Basically I copied the below code into a thread (this is the only thread in that application). I commented out hardware_init() and OSA_Init() since they are already done. I have also disabled BSPCFG_ENABLE_IO_SUBSYSTEM since I want to use the uart_edma_blocking example instead.

uint8_t dmaRxChar = 0;

uint32_t byteCountBuff = 0;

// Store runtime state structure for the eDMA driver

edma_state_t state;

// Store runtime state structure for UART driver with EDMA

uart_edma_state_t uartStateEdma;

// Config the eDMA driver

edma_user_config_t userConfig = {

.chnArbitration = kEDMAChnArbitrationRoundrobin,

.notHaltOnError = false

};

// Config the UART driver

uart_edma_user_config_t uartConfig = {

.bitCountPerChar = kUart8BitsPerChar,

.parityMode = kUartParityDisabled,

.stopBitCount = kUartOneStopBit,

.baudRate = BOARD_DEBUG_UART_BAUD

};

// Enable clock for PORTs, setup board clock source, config pin

//hardware_init();

// Call OSA_Init to setup LP Timer for timeout

//OSA_Init();

#if defined (TEST_CODE)

semaphore_t testSemaphore;

OSA_SemaCreate(&testSemaphore, 0);

osa_status_t syncStatus = OSA_SemaWait(&testSemaphore, 1000u);

#endif

// Initialize EDMA module for UART

EDMA_DRV_Init(&state, &userConfig);

UART_DRV_EdmaInit(BOARD_DEBUG_UART_INSTANCE, &uartStateEdma, &uartConfig);

// Inform to start dma-uart blocking example

byteCountBuff = sizeof(buffStart);

UART_DRV_EdmaSendDataBlocking(BOARD_DEBUG_UART_INSTANCE, buffStart, byteCountBuff, 0u);

// Inform user of what to do

byteCountBuff = sizeof(bufferData1);

UART_DRV_EdmaSendDataBlocking(BOARD_DEBUG_UART_INSTANCE, bufferData1, byteCountBuff, 0u);

while(true)

{

// Wait to receive input data

if (kStatus_UART_Success == UART_DRV_EdmaReceiveDataBlocking(BOARD_DEBUG_UART_INSTANCE, &dmaRxChar,1, OSA_WAIT_FOREVER))

{

// Echo received character

UART_DRV_EdmaSendDataBlocking(BOARD_DEBUG_UART_INSTANCE, &dmaRxChar, 1u, 0u);

}

It sends the first set of data (buffStart) to the terminal after which it crashes and goes to hardfault handler.

The problem is when I step through the code it does not crash. I can see that the DMA interrupt happens. The call back function (UART_DRV_EdmaCompleteSendData) is called which posts the semaphore (txIrqSync). It continues to send the second set of data (bufferData1).

I'm not sure if I'm doing something wrong here. If I create, pend and release the semaphore outside an interrupt handler, I don't see this issue happening.

I'm not sure if I have to do some kind of critical section protection here. Not much information available on the MQX reference manual.

Any help is greatly appreciated.

Thank you.

Re: MQX releasing a semaphore in a interrupt handler

Carlos_Musich — Fri, 04 Sep 2015 00:18:30 GMT

Hi Vivek,

Which exact functions are you calling within interrupts?

Please refer to 'MQX RTOS Reference Manual.pdf' located in C:\Freescale\KSDK_1.2.0\doc\rtos\mqx

Note that many of the lwsem functions cannot be called from interrupts.

Regards,

Carlos

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MQX releasing a semaphore in a interrupt handler

Re: MQX releasing a semaphore in a interrupt handler