Read/Write ops

To hide details I2C protocol you can use methods read($device_address, $num_bytes) and write($device_address, $data, ...) present in the I2CMaster class. These methods encapsulate the whole transaction, that is communications starts with start condition and ends with the stop.

from bitstring import Bits

i2c_master = I2CMaster()
data: Bits | None = i2c_master.read(address=0x42, num_bytes=2)
if data is None:
    print("Error")
else:
    print(data)

If transaction fails for any reason it return None. Otherwise, it returns Bits class from the bitstring library.

Method write(...) returns boolean indicating success or failure of the write operation and it accepts data to be sent in several different forms.

i2c_master = I2CMaster()
is_success: bool = i2c_master.write(0x42, data=0x10)

It is an int, then it will send one byte encoded in that int value. If it is an array of integers, that is understood as array of bytes. Naturally each int has to be a range from 0 to 255 or ValueError is raised.

is_success: bool = i2c_master.write(0x42, data=[0x07, 0x10])

If data is a string, then it has to be a string representation of bit or byte array. For example write(0x42, data=0x07) can be written like so

i2c_master.write(0x42, data="0b111")

Note that 0b111 is only 3 bits wide. This payload by default will be padded with zeroes to nearest whole number of bytes. Thus, above will become 0b00000111. If you want to be padded to a greater number of bytes, let say 2 in this example

i2c_master.write(0x42, data="0b111", num_bytes=2)

This will send two bytes to the slave device 0b0000000000000111 (or 0x0007).