Library Description

The library initializes and defines I2C and SPI driver and performs the communication with device registers by both drivers. The library offers a choice to measure the temperature in Celsius units, and the pressure in mbar units. The user can determine the oversampling ratio value for both measurements independently. For more details check the documentation.

Key functions:

• uint8_t altitude2_readPROM( uint8_t selectData, uint32_t *dataOut )- The function reads calibration data from PROM.
• uint8_t altitude2_setRatio( uint8_t tempRatio, uint8_t pressRatio )- The function determines the oversampling ratio value for temperature and pressure measurements.
• void altitude2_readData( float *tempData, float *pressData, float *altitudeData )- The function performs temperature and pressure measurements with desired oversampling ratio and performs the calculations that convert temperature data in Celsius value and pressure data in mbar value. Depending on the temperature and pressure calculated values, the function calculates the altitude value in meters.

Examples Description

• System Initialization - Initializes peripherals and pins.
• Application Initialization - Initializes I2C/SPI driver and performs the device reset, after which the calibration coefficients be read. Determines the ratio value for temperature and pressure measurements. Calibration coefficients are necessary to read after the device reset.
• Application Task - (code snippet) - Gets temperature data in Celsius value and pressure data in mbar value. Gets the calculated altitude value in meters which depends on the temperature and pressure measurements. Logs results on USB UART and repeats operation every 300 ms.

void applicationTask()
{
 altitude2_readData( &temperature, &pressure, &altitude );

 mikrobus_logWrite( "Temperature is: ", _LOG_TEXT );
 FloatToStr( temperature, text );
 mikrobus_logWrite( text, _LOG_TEXT );
 mikrobus_logWrite( " Celsius", _LOG_LINE );

 mikrobus_logWrite( "Pressure is: ", _LOG_TEXT );
 FloatToStr( pressure, text );
 mikrobus_logWrite( text, _LOG_TEXT );
 mikrobus_logWrite( " mbar", _LOG_LINE );

 mikrobus_logWrite( "Altitude is: ", _LOG_TEXT );
 FloatToStr( altitude, text );
 mikrobus_logWrite( text, _LOG_TEXT );
 mikrobus_logWrite( " m", _LOG_LINE );
 mikrobus_logWrite( "", _LOG_LINE );

 Delay_ms( 300 );
}

mikroE Libraries used in the example:

• Conversions
• I2C
• SPI
• UART

Additional notes and information

Depending on the development board you are using, you may need USB UART click, USB UART 2 click or RS232 click to connect to your PC, for development systems with no UART to USB interface available on the board. The terminal available in all MikroElektronika compilers, or any other terminal application of your choice, can be used to read the message.