MPLAB® Harmony v3 Drivers and Middleware on PIC32MZ EF MCUs Using FreeRTOS: Step 6

Open the I²C driver instance 0 (which is associated with TWIHS0). 

The call to DRV_I2C_Open() API will associate the sensor client with the I²C driver instance 0. The returned handle will be used by the application in all the subsequent calls to the driver to read temperature values from the sensor. 

app_sensorData.i2cHandle = DRV_I2C_Open( DRV_I2C_INDEX_0, DRV_IO_INTENT_READWRITE );

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Set the transfer parameters for the sensor application thread client after a valid handle to the driver is obtained. 

The transfer parameter sets the I²C clock speed to 100 kHz for this client. 

DRV_I2C_TransferSetup(app_sensorData.i2cHandle, &app_sensorData.i2cSetup);

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Open the USART synchronous driver instance 0, which is associated with UART6. 

The call to DRV_USART_Open() API will return a handle to the USART driver instance 0. The returned handle will be used by the sensor application thread in all the subsequent calls to the driver to print the temperature values on the serial terminal for this client. 

app_sensorData.usartHandle = DRV_USART_Open(DRV_USART_INDEX_0, 0);

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Submit a call to the FreeRTOS API vTaskDelay() to yield CPU control to other threads in the application for a duration equal to the temperature sampling time of the application (one second). 

vTaskDelay(APP_SENSOR_SAMPLING_RATE_IN_MSEC/portTICK_PERIOD_MS);

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Submit a blocking I²C request to read the temperature from the sensor. 

The calling thread will be blocked until the request is completed, thereby allowing other threads to run. 

if (true == DRV_I2C_WriteReadTransfer(app_sensorData.i2cHandle, APP_SENSOR_I2C_SLAVE_ADDR, (void*)&registerAddr, 1, (void*)app_sensorData.i2cRxBuffer, 2))

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Communicate the temperature-ready event and the temperature value to the EEPROM thread using the RTOS queue. 

The EEPROM task unblocks when an event/data is available in the RTOS queue. 

xQueueSend( eventQueue, (void*)&app_sensorData.eventInfo, portMAX_DELAY);

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Print the latest temperature value by making a call to DRV_USART_WriteBuffer() API, which submits a blocking USART write request. 

DRV_USART_WriteBuffer(app_sensorData.usartHandle, app_sensorData.usartTxBuffer, strlen );

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Associate the second client (EEPROM application thread client) with the I²C driver instance 0. 

This is done by opening the I²C driver instance 0 again. The call to DRV_I2C_Open () API will now associate the EEPROM application thread client with the I²C driver instance 0. The returned handle will be used by the application in all the subsequent calls (related to the EEPROM application thread client) to the driver to write/read temperature values to/from EEPROM. 

app_eepromData.i2cHandle = DRV_I2C_Open( DRV_I2C_INDEX_0, DRV_IO_INTENT_READWRITE );

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Like the sensor application thread client, set up the transfer parameters for the EEPROM application thread client after a valid handle to the driver is obtained. 

The transfer parameters set the I²C clock speed to 400 kHz for this client. 

DRV_I2C_TransferSetup(app_eepromData.i2cHandle, &app_eepromData.i2cSetup);

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Associate the second client (EEPROM application thread client) to USART synchronous driver instance 0 (which is associated with USART1). 

The call to DRV_USART_Open() API will return a handle to the USART driver instance 0. The returned handle will be used by the EEPROM application thread in all the subsequent calls to the driver to print the temperature values from the EEPROM on the serial terminal. 

app_eepromData.usartHandle = DRV_USART_Open(DRV_USART_INDEX_0, 0);

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Block the EEPROM application thread until a request is available in the RTOS queue. 

The scheduler will unblock the EEPROM thread when an event/data is available in the RTOS queue. Depending on the event received in the RTOS queue, the EEPROM task either writes or reads the temperature value from the EEPROM. 

xQueueReceive( eventQueue, &app_eepromData.eventInfo, portMAX_DELAY );

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Submit blocking I²C requests to write temperature from the sensor to EEPROM. 

The calling thread will be blocked until the request is completed thereby allowing other threads to run. 

        if (true == DRV_I2C_WriteTransfer(app_eepromData.i2cHandle, APP_EEPROM_I2C_SLAVE_ADDR, (void *)app_eepromData.i2cTxBuffer, 2))
        {                
            /* Check if EEPROM has completed the write operation */
            while (false == DRV_I2C_WriteTransfer(app_eepromData.i2cHandle, APP_EEPROM_I2C_SLAVE_ADDR, (void *)&dummyData, 1));
        }

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Submit blocking I²C request to read the temperature from the EEPROM to submit for printing on the serial terminal. 

The calling thread will be blocked until the request is completed, thereby allowing other threads to run. 

if (true == DRV_I2C_WriteReadTransfer(app_eepromData.i2cHandle, \
                APP_EEPROM_I2C_SLAVE_ADDR, app_eepromData.i2cTxBuffer, 1,\
                app_eepromData.i2cRxBuffer, 5))

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Print the logged temperature value from EEPROM by making a call to the DRV_USART_WriteBuffer() API by calling the EPPROM application thread function APP_EEPROM_PrintTemperature() which submits a blocking USART write request. 

APP_EEPROM_PrintTemperature(app_eepromData.i2cRxBuffer, app_eepromData.wrIndex);

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Register an event handler (callback) with the File System Service by calling API SYS_FS_EventHandlerSet().

The event handler is called by the File System Service when the mount/unmount operation has been completed.
Register an event handler (callback) with the USB Host stack layer by calling API USB_HOST_EventHandlerSet(). The event handler is called by the USB Host stack layer when several USB host events occur.
Call API USB_HOST_BusEnable () to enable operation of the USB Host Bus.

SYS_FS_EventHandlerSet((void *)APP_SYSFSEventHandler, (uintptr_t)NULL);
USB_HOST_EventHandlerSet(APP_USBHostEventHandler, 0);
USB_HOST_BusEnable(0);

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Call API USB_HOST_BusIsEnabled() to wait in the USB application thread state for the USB host bus to be enabled.

if(USB_HOST_BusIsEnabled(0))

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Call the File System API SYS_FS_FileOpen() to create a new text file Temperature_Sensor_Data.txt to write temperature sensor data to the connected USB thumb drive. 

The text file will be created only if there is no existing file of the same name in the thumb drive.

app_usb_threadData.fileHandle = SYS_FS_FileOpen("/mnt/myDrive1/Temperature_Sensor_Data.txt", (SYS_FS_FILE_OPEN_APPEND_PLUS));

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Submit a request to write temperature sensor data to the USB thumb drive by calling the File System API SYS_FS_FileWrite(). 

The API would then return when the data is successfully written to the thumb drive, otherwise, it would return an error. 

if (SYS_FS_FileWrite( app_usb_threadData.fileHandle, (const void *) writeData, strlen) == -1)

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Call the File System API SYS_FS_FileClose () to close the text file Temperature_Sensor_Data.txt once the temperature sensor data is written. 

SYS_FS_FileClose(app_usb_threadData.fileHandle);

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Block the USB application thread until a request is available in the RTOS queue. 

The scheduler will unblock the USB thread when an event/data is available in the RTOS queue. Depending on the event received in the RTOS queue, the USB task writes the temperature value to the USB thumb drive. 

xQueueReceive( eventQueue, &app_usb_threadData.eventInfo, portMAX_DELAY );

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Associate the third client (user input application thread client) to USART synchronous driver instance 0 (which is associated with USART1). 

The call to DRV_USART_Open() API will return a handle to the USART driver instance 0. The returned handle will be used by the User Input application thread in all the subsequent calls to the driver to read a user key press on the serial terminal. 

app_user_inputData.usartHandle = DRV_USART_Open(DRV_USART_INDEX_0, 0);

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Submit a blocking USART read request. The user input thread will be unblocked when a character is received on the USART. 

After unblocking, it communicates the request to read data from EEPROM to the EEPROM thread via the RTOS queue. 

if (DRV_USART_ReadBuffer(app_user_inputData.usartHandle, &usartData, 1 ) == true)

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xQueueSend( eventQueue, &app_user_inputData.eventInfo, portMAX_DELAY );

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