CCS811 Driver for C

Originally designed and created for UMass ECE Senior Design Project Team 03 Weatherbox.

Based off the Bosch BME280 C Driver.

What's Included

ccs811_defs.h

• Includes #defines for any major addresses, length, sensor operation modes, bit masks, etc.

• Includes type definitions for function pointers for reading, writing, and delaying.

• Includes struct definitions for

  • Measurement Data (eCO2, tvoc, status, error_id, raw_data)

  • Threadhold Registers (low, high and hysteresis)

  • Raw Data (current, and raw ADC reading)

  • Environmental Data (humidity percentage & fraction, temperature percentage and fraction)

  • NTC Data Register (Voltage across R_ref and R_ntc)

  • Firmware Boot Version (Major, Minor, and Trivial version numbers)

  • Firmware App Version (Major, Minor, and Trivial version numbers)

  • CCS811 Device Struct

    • Hardware ID

    • Hardware Version

    • Device Address

    • Status Register

    • Measurement Mode Register

    • Error Register

    • CCS811 Function Pointer for Reading

    • CCS811 Function Pointer for Writing

    • CCS811 Function Pointer for Delaying

ccs811.h & ccs811.c

• ccs811_init - Initialization

  • Takes in a pointer to the CCS811 device struct as an argument.

  • Goes through initialization process for CCS811 driver.

  • Attempts each portion of the process 5 times before running resulting error code.

• ccs811_set_regs - Set Registers

  • Takes in a pointer to the internal CCS811 register address, a pointer to the data to write to the register, the length of the data, and a pointer to the CCS811 device struct as arguments.

  • Writes data to the specified internal CCS811 register address. Returns 0 on success. Other codes mean error.

• ccs811_read_regs - Read Registers

  • Takes in a pointer to the internal CCS811 register address, a pointer to the data buffer to store the data, the length of the data, and a pointer to the CCS811 device struct as arguments.

  • Reads data from the specified internal CCS811 register address to the data buffer. Returns 0 on success. Other codes mean error.

• ccs811_read_status_reg - Read Status Register

  • Takes in a pointer to the CCS811 device struct as an argument.

  • Utilizes ccs811_read_regs to read from status register into the CCS811 device structs status register.

• ccs811_read_meas_mode_reg - Read Measurement Mode Register

  • Takes in a pointer to the CCS811 device struct as an argument.

  • Utilizes ccs811_read_regs to read from the measurement mode register into the CCS811 device structs measurement mode register.

• ccs811_set_meas_mode_reg - Set Measurement Mode Register

  • Takes in a pointer to the CCS811 device struct as an argument.

  • Utilizes ccs811_read_regs to read from the measurement mode register into the CCS811 device structs measurement mode register.

• ccs811_read_alg_result_data - Reads Algorithm Result Data Registers

  • Takes in a pointer to the CCS811 measurement data struct, and a pointer to the CCS811 device struct as arguments.

  • Utilizes ccs811_read_regs to read from the Algorithm Result Data register.

  • Formats and places data into the algorithm data struct.

• ccs811_read_raw_data - Reads Raw Data Registers

  • Takes in a pointer to the CCS811 raw data struct, and a pointer to the CCS811 device struct as arguments.

  • Utilizes ccs811_read_regs to read from the Raw Data register.

  • Formats and places data into the raw data struct.

• ccs811_set_env_data - Set Environmental Data Register

  • Takes in a pointer to the CCS811 environmental data struct, and a pointer to the CCS811 device struct as arguments.

  • Utilizes ccs811_set_regs to write to the Environmental Data register.

  • Formats the data from the environmental data struct into a buffer for writing.

• ccs811_read_ntc - Read NTC Register

  • Takes in a pointer to the CCS811 NTC struct, and a pointer to the CCS811 device struct as arguments.

  • Utilizes ccs811_read_regs to read from the NTC register.

  • Formats read data into the NTC struct.

• ccs811_set_threshold_reg - Set Threshold Register

  • Takes in a pointer to the CCS811 threshold struct, and a pointer to the CCS811 device struct as arguments.

  • Utilizes ccs811_set_regs to write to the Threshold register.

  • Formats threshold data into buffer for writing.

• ccs811_read_baseline_reg - Read Baseline Register

  • Takes in a pointer to a 16 bit integer as the baseline, and a pointer to the CCS811 device struct as arguments.

  • Utilizes ccs811_read_regs to read from the Baseline register.

  • Formats baseline data into the 16 bit integer.

• ccs811_set_baseline_reg - Set Baseline Register

  • Takes in a pointer to a 16 bit integer as the baseline, and a pointer to the CCS811 device struct as arguments.

  • Utilizes ccs811_set_regs to write to the Threshold register.

  • Formats baseline data into buffer for writing.

• ccs811_read_hw_id - Read Hardware ID Register

  • Takes in a pointer to the CCS811 device struct as the argument.

  • Utilizes ccs811_read_regs to read from the hardware ID register.

• ccs811_read_hw_version - Read Hardware Version Register

  • Takes in a pointer to the CCS811 device struct as the argument.

  • Utilizes ccs811_read_regs to read from the hardware version register.

  • Formats data into the hw_version struct.

• ccs811_read_fw_boot_version - Read Firmware Boot Version Register

  • Takes in a pointer to the CCS811 device struct as the argument.

  • Utilizes ccs811_read_regs to read from the firmware boot version register.

  • Formats data into the fm_boot_version struct.

• ccs811_read_fw_app_version - Read Firmware App Version Register

  • Takes in a pointer to the CCS811 device struct as the argument.

  • Utilizes ccs811_read_regs to read from the firmware app version register.

  • Formats data into the fm_app_version struct.

• ccs811_read_error_id - Read Error Register

  • Takes in a pointer to the CCS811 device struct as the argument.

  • Utilizes ccs811_read_regs to read from the error register.

• ccs811_perform_sw_reset - Performs Software Reset on the device

  • Takes in a pointer to the CCS811 device struct as the argument.

  • Utilizes the ccs811_set_regs to perform a software reset on the device.

• ccs811_perform_app_erase - Performs Application Reset on the device

  • Takes in a pointer to the CCS811 device struct as the argument.

  • Utilizes the ccs811_set_regs to perform the application reset on the device.

• ccs811_set_app_data - Set Application Data Register

  • Takes in a pointer to application data, and the CCS811 device struct as the arguments.

  • Utilizes the ccs811_set_regs to set the application data on the device.

• ccs811_app_start - Start the Sensor

  • Takes in a pointer to the CCS811 device struct as the argument.

  • Utilizes the ccs811_set_regs to set the device from boot mode to application mode.

• ccs811_convert_temp_and_humid_to_env_data - Set Measurement Mode Register

  • Takes in a 32 bit int for humidity, a 32 bit int for temperature, and a pointer to the environmental data struct

  • Converts given humidity and temperature into the environmental data structure. Creates the percentage and fraction values.

How to Setup

1. Create read, write, and delay functions

2. Create CCS811 Struct with

   • Appropriate I2C address

   • Measurement Mode

   • Read, write, and delay function pointers

   • Setting hardware id, version, status reg, and error register to 0

3. Run ccs811_init

4. Run ccs811_read_fw_boot_version

5. Run ccs811_read_fw_app_version

6. Run ccs811_read_ntc if using external temperature sensor hooked up with resistors

7. Run ccs811_read_baseline_reg

8. Run ccs811_status_reg - Check error bit

How to read data

1. Run ccs811_status_reg - Check data ready bit

2. If data is ready, run ccs811_read_alg_result_data

3. Set environmental data by running ccs811_set_env_data

4. Go to step 1.