Registers access

To farther simplify interation with devices that have concepts of registers as described above

i2c_master = I2CMaster()
reg_data: Bits | None = i2c_master.read_register(
    0x42, RegisterAddress(address=0x07, bus_width_in_bytes=1)
)

Above will read one byte from the register whose address is one byte long 0x07 or return None if transaction fails for any reason.

There is a shortcut for the above though. If register address is one byte wide, then you simply pass register address as an int.

i2c_master.read_register(0x42, register=0x07)

This will raise ValueError if register address is outside of range from 0 to 255.

If register holds let say 4 bytes, then you can read it like so

reg_data: Bits | None = i2c_master.read_register(
    0x42, RegisterAddress(address=0x07, bus_width_in_bytes=1), num_bytes=4
)

Writing register has a bit more moving parts. For example write 0x11 into register 0x07 on device at address 0x42

i2c_master = I2CMaster()
data: Bits | None = i2c_master.write_register(0x42, register=0x7, data=0x11)

It returns data that was written into a device (in this case 0x11) or None if transaction failed for any reason. Like with read_register(...) register address can be an int for one byte wide address or an instance of RegisterAddress. Like with write(...) function above, data can be an int for one byte, array of ints one for each byte or a string representing bit array and optional argument num_bytes will pad it the specific number of bytes or if not provided to the nearest number of bytes to fit payload in.

To confirm that data was acutally written you can set read_back=True (default is False).

data = i2c_master.write_register(0x42, register=0x7, data=0x11, read_back=True)

This will write register and will then read it back. Normally these two operations, register write and then read will be in two separate transaction as not every dongle supports restart between write and read op. If you dongle does support it though you can indicate that you want to use restart and do everything that this function does in one single transaction by setting use_restart=True.