This is library for Si7021 module. It has been created for RP2040 microcontroller placed inside Raspberry Pi Pico. Library is written in C++ and it uses Pico SDK (link). Si7021 is a temperature and humidity sensor, with I2C interface. Library was created based on IC documentation (link).
- Si7021 documentation - https://www.silabs.com/documents/public/data-sheets/Si7021-A20.pdf
- Pico SDK - https://www.raspberrypi.com/documentation/pico-sdk/index_doxygen.html#index
Example use of this library is demonstrated in example.cpp file located in src\ folder.
#include <stdio.h>
#include "pico/stdlib.h"
#include "hardware/i2c.h"
#include <iostream>
#include <list>
#include <inttypes.h>
#include "si7021.h"
int main() {
stdio_init_all();
gpio_init(21);
gpio_set_dir(21, true);
i2c_init(i2c0, 100000);
gpio_set_function(0, GPIO_FUNC_I2C);
gpio_set_function(1, GPIO_FUNC_I2C);
gpio_pull_up(0);
gpio_pull_up(1);
Si7021::Si7021 si7021(i2c0);
si7021.setHeater(true);
si7021.setResolution(Si7021::Resolution::RH11T11);
si7021.setHeaterConfig(Si7021::HeaterConfig::hc0100);
int counter = 0;
while(true){
printf("Si7021 Serial number: %#" PRIx64 "\n", si7021.askForSerialNumber());
printf("Si7021 Firmware: %#x\n", si7021.askForFirmwareRev());
printf("Si7021 Humidity: %.2f[%%]\n", si7021.askForHumidity());
printf("Si7021 Temperature: %.2f[°C]\n", si7021.askForTemperature());
printf("Si7021 User register: %i\n", si7021.askForRegisterData(Si7021::Register::User));
printf("Si7021 Heater register: %i\n", si7021.askForRegisterData(Si7021::Register::Heater));
printf("Si7021 Resolution: %i\n", si7021.askForResolution());
printf("Si7021 Heater status: %i\n", si7021.askForHeater());
printf("Si7021 Heater config: %i\n", si7021.askForHeaterConfig());
printf("-----------------------------------------------------\n");
if(counter++ == 20){
printf("Si7021 Heater and User register reset!\n");
si7021.resetRegister(Si7021::Heater);
si7021.resetRegister(Si7021::User);
}
sleep_ms(1000);
}
}Default constructor, takes one argument which is utilized I2C controller. Using i2c0 or i2c1 macro is sufficient.
Si7021::Si7021 Si7021(i2c0);This Si7021 library provides methods that enable user to interface with most of the hardware included inside Si7021 module.
Methods of this class can be divided into three types of functions. This type of functions can be differentiated by its suffix:
- askFor...() - this type of methods get information from Si7021 module directly via I2C commands. Every time this type of method is used, returned data is coming directly from the module. During execution of this methods, class type variables associated with returned type of data are being updated.
- get...() - this type of functions are using class membervariables, they DO NOT send I2C commands.
- set...() - this methods are used to set parameters of Si7021 module via I2C.
List of availablefunctions:
// Serial number and Firmware
uint64_t askForSerialNumber();
uint64_t getSerialNumber() const;
uint8_t askForFirmwareRev();
uint8_t getFirmwareRev() const;
// Humidity
float askForHumidity();
float getHumidity() const;
// Temperature
float askForTemperature();
float getTemperature() const;
float askForTemperaturePrevRH();
// Registers
bool resetRegister(Register Register);
uint8_t askForRegisterData(Register Register);
bool setRegister(uint8_t newRegisterByte, Register Register);
// Resolution
Resolution getResolution() const;
Resolution askForResolution();
bool setResolution(Resolution res);
// Heater
bool getHeater() const;
bool askForHeater();
bool setHeater(bool status);
bool setHeaterConfig(HeaterConfig heater);
HeaterConfig askForHeaterConfig();
HeaterConfig getHeaterConfig() const;
// Device
void resetDevice();Library has built in 3 enum types dedicated to use in its methods.
Resolution represents accuracy of temperature and humidity data measurement.
enum Resolution{
RH12T14,
RH08T12,
RH10T13,
RH11T11
};Register enum used for pointing which register to use.
enum Register{
Heater,
User
};Heater config enum used for defining configuration of the heater.
enum HeaterConfig{
hc0000,
hc0001,
hc0010,
...
...
hc1111
};
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