RTOS/TM4C123GH6PM: Task blocking and Terminating other Tasks

Yashwanth Gandeti

Intellectual 595 points

Part Number: TM4C123GH6PM

Tool/software: TI-RTOS

Hi all,

I am new to TI-RTOS.

I'm using following configurations for my project

CCSv8.1.0 , TI-RTOS- 2.16.00.08, TIVA Ware: 2.1.4.178;xdc : 3.32.00.06Laptop OS: Windows 10

I have 4 Tasks in my system. In one of those tasks. I want to get IMU Sensor Data when ever a button is pressed. To acheive this I configured to post Semaphore when ever the button is pressed

Code snippets as follows:

/* Callback function for the GPIO interrupt on up Button.*/
void gpioButtonFxn1(unsigned int index)
{
Semaphore_post(IMUSem);

}

The Task implementation is as follows:

void get_imu()
{
// GPIO_toggle(Board_LED_BLUE);

I2C_Handle i2c;
I2C_Params i2cParams;
uint8_t pwr;
pwr = 0x00;

//Create I2C for usage
I2C_Params_init(&i2cParams);
i2cParams.bitRate = I2C_400kHz;
i2c = I2C_open(IMU_SENSOR, &i2cParams);
if (i2c == NULL)
{
System_abort("Error Initializing I2C\n");
}
else
{
System_printf("I2C Initialized!\n");
}

// Initialize the MPU6050
signal.writeRegister(i2c,0x6B, 0x80);    // This line making the this Task to go into blocked state and other tasks to terminate state 
signal.readRegister(i2c, 0x6B, &pwr, 1);
do {
signal.readRegister(i2c, 0x6B, &pwr, 1);
} while (pwr & 0x40 != 0x40);

// Use PLL with X axis gyroscope reference
signal.writeRegister(i2c,0x6B, 0x01);
// Enable I2C Master mode
signal.writeRegister(i2c,0x6A, 0x20);
// Set sample rate divider
signal.writeRegister(i2c,0x19, 0x13);
signal.writeRegister(i2c,0x67, 0x11);

GPIO_write(Board_LED_RED, Board_LED_OFF);

while(1)
{
Semaphore_pend(IMUSem, BIOS_WAIT_FOREVER);
while (GPIOPinRead(GPIO_PORTB_BASE, GPIO_PIN_2) == GPIO_PIN_2);
signal.readRegister(i2c, 0x3B, (uint8_t *) &signal.imu.mpu6050, 14);
}

//Deinitialized I2C
I2C_close(i2c);
System_printf("I2C closed!\n");
System_flush();
}

My WriteRegister() as follows:

void writeRegister(I2C_Handle handle, uint16_t regAddr, uint16_t value)
{
    uint8_t             txBuffer[4];
    I2C_Transaction     i2cTransaction;

    i2cTransaction.slaveAddress = MPU6050_I2C_ADDRESS;

     //Write to a 16-bit status register
    i2cTransaction.writeBuf = txBuffer;
    i2cTransaction.writeCount = 2;
    i2cTransaction.readCount = 0;

    txBuffer[0] = regAddr & 0xFF; //LB Addr
    txBuffer[1] = value   & 0xFF;

    if (!I2C_transfer(handle, &i2cTransaction)) {
        GPIO_write(Board_LED_RED, Board_LED_ON);
        System_abort("Bad I2C transfer!");
    }
}

and readRegister() as follows:

void readRegister(I2C_Handle handle,
                  uint16_t regAddr,
                  uint8_t *data,
                  size_t   length)
{
    uint8_t             txBuffer[2];
    I2C_Transaction     i2cTransaction;

    i2cTransaction.slaveAddress = MPU6050_I2C_ADDRESS;

     //Write to a 16-bit status register
    i2cTransaction.writeBuf = txBuffer;
    i2cTransaction.readBuf = data;
    i2cTransaction.writeCount = 1;
    i2cTransaction.readCount = length;

    txBuffer[0] = regAddr & 0xFF; //LB Addr

    if (!I2C_transfer(handle, &i2cTransaction)) {
        GPIO_write(Board_LED_RED, Board_LED_ON);
        System_abort("Bad I2C transfer!");
    }
}

My .cfg file configuration for Imu task and semaphore as follows:

var task3Params = new Task.Params();
task3Params.instance.name = "imu";
task3Params.priority = 2;
Program.global.imu = Task.create("&get_imu", task3Params);
var semaphore0Params = new Semaphore.Params();
semaphore0Params.instance.name = "IMUSem";
Program.global.IMUSem = Semaphore.create(null, semaphore0Params);

Below is the  screen shot of the ROV:

when debugger in main():

After the line in get_imu() task

signal.writeRegister(i2c,0x6B, 0x80);

Kindly some one help me in this.

Thanks in Advance.

Regards,

Yashwanth Gandeti.

over 6 years ago

0 Charles Tsai over 6 years ago

TI__Guru**** 184346 points

Hi,
So what is the problem? After you take the interrupt and the semaphore_post is executed, what happened to the get_imu? Didn't it run the signal.readRegister?

0 Yashwanth Gandeti over 6 years ago in reply to Charles Tsai

Intellectual 595 points

Hi Charles,

If my understanding is not wrong.

1.Here for my project I'm using Static way of configuration.All the task are ready to run when BIOS_Init(); is called. So before calling the main() Tasks are ready to run is it?

void taskfxn(){

/*Prolog*/
....
....
....
while(1){
semaphore_pend();
....
...
...
...
}
/*Epilog*/
}

In the above pseudo code prolog would have been ran before its wait for semaphore. Comparing the above code to my code I'm going into blocked state when i'm in a "prolog" part of the code not in the while(1) part of the code. Before posting the semaphore get_imu task is going into blocked state and remaining tasks into terminated states.

While debugging I came to know that I2C_transfer(handle, &i2cTransaction) in writeRegister() is creating this problem. Can you help me in this.

Regards,

Yashwanth Kumar

0 Yashwanth Gandeti over 6 years ago in reply to Yashwanth Gandeti

Intellectual 595 points

Hi,

I implemented above code in newly created project, its running smoothly. But I don't know where i did mistake.
Regards,
Yashwanth.

0 Charles Tsai over 6 years ago in reply to Yashwanth Gandeti

TI__Guru**** 184346 points

Yashwanth Gandeti said:
In the above pseudo code prolog would have been ran before its wait for semaphore. Comparing the above code to my code I'm going into blocked state when i'm in a "prolog" part of the code not in the while(1) part of the code. Before posting the semaphore get_imu task is going into blocked state and remaining tasks into terminated states.

Your understanding about the semaphore is correct. Once the semaphore_pend is executed it will not execute any more code further until semaphore_post is issued.

0 Charles Tsai over 6 years ago in reply to Yashwanth Gandeti

TI__Guru**** 184346 points

Yashwanth Gandeti said:
I implemented above code in newly created project, its running smoothly. But I don't know where i did mistake.

Glad that your problem is somehow resolved. What other things did you do other than creating a new project? Unless you can reproduce the problem again in this newly created project, I don't see problem with your understanding of using semaphore. I will close this thread for now. If you have new questions or see problems again you can create a new thread.

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RTOS/TM4C123GH6PM: Task blocking and Terminating other Tasks