Arduino/ESP32 library to wrap TwoWire device classes.
While writing several supoport libraries for I2C/TwoWire devices it became cumbersome to keep implementing the read/write functions and sorting out the byte order for each device. Also most libraries I found as an example all assumed that 'Wire' was going to be used as the only TwoWire bus. I wanted to be able to support several busses and several devices on each bus. On top of that each library was randomly reconfiguring io-pins, bus speeds etc which would make them conflict each other. My view on this is that a developer should first configure the bus, speed, pins etc and then instantiate devices on them. That is what this libary supports.
It's major features are:
- A common place to store the read/write address/register functions for several bit widths (8/16/24) so libraries can share them.
- These devices all supprt which 'Wire' device you wish to use and on which address. Therefor you can easily add multiple sensors on one or more buses and make multiple instances of this library.
There is a less sophisticated twin: lib-SPIDevice
Inherited your devices from TwoWireDevice:
#define MYDEVICE_ADDRESS_DEFAULT 0x00
class MyDevice : public TwoWireDevice
{
public:
//con-/destructors
MyDevice(TwoWire& wire, const uint8_t addr = MYDEVICE_ADDRESS_DEFAULT) : TwoWireDevice(wire, addr) {};
MyDevice(const uint8_t addr = MYDEVICE_ADDRESS_DEFAULT) : TwoWireDevice(addr) {};
~MyDevice() {};
};
Then use the TwoWireDevice's protected functions to read/write from/to the device's :
read()/write(), an arbitrary number of bytesread8()/write8(), one byte
Or use the register funtions to read/write register based devices:
readreg8/writereg8readreg16/writereg16readreg24/writereg24
Of which each of them is available in MSB>LSB or LSB>MSB mode:
readreg8_ML(), MSB left, LSB rightreadreg8_LM(), LSB left, MSB right
After each call to the Wire library the result is stored and can be retreived with the last_error() method, or a string can be obtained with last_error_text() for debugging purposes.
Personally I find it good practice to, at first, disable copy constructors and assignment operators until I've thought about them. In TwoWireDevices this is seldom something you want to support, I guess.. So I've disabled them in TwoWireDevice.h. Implement your own in your (inherited) device to re-enable them after you have done the thinking ;)
private:
TwoWireDevice(const TwoWireDevice&);
TwoWireDevice& operator=(const TwoWireDevice&);
I'm an advocate of Platform-IO. To use this library with your PlatformIO project, add this to you platformio.ini environment:
lib_deps =
https://github.com/knifter/lib-TwoWireDevice
Some example devices are between my github repositories, like:
- SHT30/31/35 Temperature/Humidity sensor
- SHT40/41/45 Temperature/Humidity sensor
- CCS811 Gas Sensor
- BME280 Humidity/Pressure/Temperature Environmental Sensor