MicroPython Forum (Archive)

Hi I'm very new to Python and wondering if there is a correct form passing data to a UART on pi Pico
I've found two different ways construct the payload via a byte-array and a sequence of bytes.
My question is do I have potential issues with either/both?
Many thanks in advance.

# byte-array
>>>modDataBA = bytearray(b'\x05\x03\x07\x00\x00\x00\x00\x0A')
>>>modDataBA.append(s0Dis)
>>>modDataBA.append(s0Dos)
>>>modDataBA: bytearray(b'\x05\x03\x07\x00\x00\x00\x00\n\x01\x01')

# byte-sequence
>>>modDataBY = b'\x05\x03\x07\x00\x00\x00\x00\x0A'+(s0Dis).to_bytes(1,'big')+(s0Dos).to_bytes(1,'big')
>>>modDataBY: <class 'bytes'> b'\x05\x03\x07\x00\x00\x00\x00\n\x01\x01'

When UART.write(buf) is called, the buf passed can be any object that implements the buffer protocol such as bytes, bytearray, memoryview and str. See also buffer protocol.

Thanks for pointing me in that direction.

I had google around and Buffer Object & Protocol get deep very quickly.
But found this helpful https://docs.python.org/3/glossary.html ... ike-object
Though it looks like micro-python treats str differently from CPython.

When I started with micro-python I was sending AT commands which are strings
>>> atCmd = cmd + '\r\n'
>>> uart.write(atCmd)

And didn't question why it just worked so now know.
I've moved on to doing Modbus which is a binary protocol