Safe&Sound: Wearable Tracking Device for Miners - 10: Interfacing BME280 Environmental Sensor

Title: Wearable Tracking Device for Miners

By: sunnyiut                   

Design Challenge: Safe and Sound Wearables

Blog number: 10

Intro:

This blog is based on MSP432P401r and BME280 Environmental Sensor interface.

Objective:

The BME280 Environmental Sensor will provide three different measurements.

• ambient temperature
• ambient relative humidity
• atmospheric pressure

According to my project proposal I have to design a wearable device mounted on the wrist of the Miners.

This wearable device consists of several sensors to collect environmental information.

In this blog post, I'll focus on

     - the interfacing of the BME280 and the MSP432P401r MCU

     - display the ambient temperature, humidity and pressure on TFT

     - send data to PC UART for graphical representation [only one parameter at once]

Components:

• Sensors Boosterpack
• MSP432 Launchpad
• TFT Proto
• mikroplot [UART PC GUI]

Compiler:

MikroC pro for ARM - from MikroElektronika

Firmware:

Full source code and circuit diagram can be found in LIBSTOCK.

dependencies -

• • BME280_Driver.c [weather click]
  • BME280.c
  • mikroplot UART.c [mikroplot]

libraries -

• • TFT
  • TFT def

BME280 [BOOSTXL-SENSORS]:

BOOSTXL-SENSORS boosterpack carries BME280, an integrated environmental sensor from BOSCH.

It’s a small low power single chip sensor that measures temperature, pressure and humidity.

It communicates with the MSP432 Launchpad through I2C.

BME280  I2C address = 0x77

Interfacing:

Initialization parameters -

void BME280_INIT() {
  BME280_SetStandbyTime(BME280_STANDBY_TIME_1_MS);                              // Standby time 1ms
  BME280_SetFilterCoefficient(BME280_FILTER_COEFF_16);                          // IIR Filter coefficient 16
  BME280_SetOversamplingPressure(BME280_OVERSAMP_16X);                          // Pressure x16 oversampling
  BME280_SetOversamplingTemperature(BME280_OVERSAMP_2X);                        // Temperature x2 oversampling
  BME280_SetOversamplingHumidity(BME280_OVERSAMP_1X);                           // Humidity x1 oversampling
  BME280_SetOversamplingMode(BME280_NORMAL_MODE);
}

Configuration -

void BME280_config(){
     BME280_ReadCalibrationParams();                                               //Read calibration parameters
     BME280_SetOversamplingPressure(BME280_OVERSAMP_1X);
     BME280_SetOversamplingTemperature(BME280_OVERSAMP_1X);
     BME280_SetOversamplingHumidity(BME280_OVERSAMP_1X);
     BME280_SetOversamplingMode(BME280_FORCED_MODE);

     while(BME280_IsMeasuring());
     BME280_ReadMeasurements();
     }

Circuit Diagram:

     MSP432P401r with BME280                                             TFT display connection

Output:

The output of BME280 is pretty stable.

For indoor experiment, it gives the following readings -

• ambient temperature = 30.6 'C
• relative humidity = 79.8 %
• atmospheric pressure = 100.1 KPa

I have sent these data [one parameter at a time] to PC GUI for plotting.

I have used 'mikroplot' to graphically represent continuous 8 seconds readings.

Temperature -

Humidity -

Pressure -

That's the end of this blogpost. In my next blog, I'll interface the TMP007 temperature sensor and display the output data on TFT.