pico-sensor-lib

Lightweight I2C Sensor C Library for Raspberry Pi Pico SDK

This library contains I2C Sensor (drivers) that were initially created for FanPico project.

Supported Sensors

List of currently supported sensors:

Sensor Type	Aliases	Possible Addresses	Description	Notes
ADT7410		0x48, 0x49, 0x4a, 0x4b	16bit Digital Temperature Sensor, 0.5C accuracy
AHT1x			AHT1x Series Temperature and Humidity sensors (AHT10, AHT11 ,...)
AHT2x			AHT2x Series Temperature and Humidity sensors (AHT20, AHT21 ,...)
AM2320		0x5c	Temperature and Humidity Sensor, 0.5C accuracy	Not found when scanning bus. May not work above 100kHz bus speeds.
AS621x	AS6212, AS6214, AS6218		AS621x Series sensors: AS6212 (0.2C), AS6214 (0.4C), AC6218 (0.8C)
BMP180			16bit, 0.5C accuracy
BMP280		0x76, 0x77	20bit, 0.5C accuracy
DPS310		0x77, 0x76	24bit, 0.5C accuracy
HDC302x	HDC3022, HDC3021, HDC3020	0x44, 0x45, 0x46, 0x47	HDC302x Series Temperature and Humiditysensors
HTS221		0x5f	Temperature and Humidity Sensor
HTU21D		0x40	Temperature and Humidity Sensor, 0.4C accuracy	Not found when scanning bus (SYS:I2C:SCAN?)
HTU31D		0x40, 0x41	Temperature and Humidity Sensor, 0.3C accuracy
LPSxx	LPS22, LPS25, LPS28, LPS33, LPS35	0x5d, 0x5c	LPSxx Series Temperature and Pressure sensors
MCP9808			Digital Temperature Sensor, 0.5C accuracy
MPL115A2		0x60	Digital Barometer	Temperature sensor not calibrated.
MPL3115A2		0x60	Temperature and Pressure sensor with Altimetry, 1C accuracy
MS5611		0x76, 0x77	Temperature and Pressure Sensor	Not found when scanning bus (SYS:I2C:SCAN?)
MS8607		0x76 and 0x40	Temperature, Humidity and Pressure Sensor	Not found when scanning bus (SYS:I2C:SCAN?), appears as two seprate devices.
PCT2075			Digital Temperature Sensor, 1C accuracy
SHT3x	SHT30, SHT31, SHT35	0x44, 0x34	SHT3x Series Temperature and Humidity sensors	Not always found when scanning bus (SYS:I2C:SCAN?)
SHT4x	SHT40, SHT41, SHT43, SHT45	0x44	SHT4x Series Temperature and Humidity sensors	Not always found when scanning bus (SYS:I2C:SCAN?)
SHTC3		0x70	Temperature and Humidity sensor, 0.2C accuracy
SI7021		0x40	Temperature and Humidity sensor, 0.4C accuracy
STTS22H		0x38, 0x3c, 0x3e, 0x3f	Temperature Sensor, 0.5C accuracy
TC74	TC74A0	0x48 - 0x4f	Digital Thermal Sensor, 2C accuracy
TMP102		0x48, 0x49, 0x4a, 0x4b	Temperature Sensor, 2C accuracy
TMP117		0x48, 0x49, 0x4a, 0x4b	Temperature Sensor, 0.1C accuracy

Usage

Including pico-sensor-lib in a project

First, get the library (this example adds it as a submodule to existing repository):

$ mkdir libs
$ cd libs
$ git submodule add https://github.com/tjko/pico-sensor-lib.git

Then to use this library, include it in your CMakeLists.txt file:

# Include pico-sensor-lib library.
add_subdirectory(libs/pico-sensor-lib)

Also add pico_sensor_lib in target_link_libraries statement:

target_link_libraries(myprogram PRIVATE
  ...
  pico_sensor_lib
  )

Using pico-sensor_lib library

This library is meant to be used in "non-blocking" fashion, where measurement is first initiated using i2c_start_measurement() call, and then (after measurement is complete) results are read using i2c_read_measurement() call.

Initializing a sensor

First a sensor must be initialized using i2c_init_sensor() function. This function returns context that then can be used to perform measurements on the sensor.

// Initialize sensor
void *ctx = NULL;
int res = i2c_init_sensor(get_i2c_sensor_type("DPS310"), i2cbus, 0x77, &ctx);
if (res) {
   // failed to initialize sensor...
}

Performing Measurements

Measurements are done by first intiating measurement using i2c_start_measurement(), and then waiting (at least) the time it takes for sensor to perform a measurement. Results can then be collected by calling i2c_read_measurement(). This function returns number of milliseconds to wait for sensor to complete its measurement(s).

int delay = i2c_start_measurement(ctx);
if (delay < 0) {
  // failed to initiate measurement...
}

Wait at least for delay milliseconds, before reading the measurement results:

float temp, pressure, humidity;
int res = i2c_read_measurement(ctx, &temp, &pressure, &humidity);
if (res) {
  // failed to read measurements...
}

Examples

See FanPico source code