UART won't send all MIDI control messages [solved]

[Grumpy_Mike]

I am trying to send some MIDI messages through the UART. I am finding that every message above 0xB0 produces nothing on the output as seen by the MIDI monitor app on a Mac.

This is the code I am using:-

Code: Select all

"""
MicroPython code to write from UART1 on the Pico
sends some MIDI messages
"""
from machine import UART
from machine import Pin

ser = UART(1, 31250, tx=Pin(8), rx=None) # no recieve

# send control message - works OK
ser.write(chr(0xB0))
ser.write(chr(0x00)) # write bank select msb
ser.write(chr(0x00)) # set to a zero

# send a program change message - produces nothing
ser.write(chr(0xC0))
ser.write(chr(27))

# ask for retune - produces nothing
ser.write(chr(0xF8))

Is there something wrong with me using chr(), if so how do you send defined bytes?
Other messages like note on and note off work this way.

[Roberthh]

why not using ser.write(b'\xC0'))? That avoids problems with encoding.

[Grumpy_Mike]

why not using ser.write(b'\xC0'))? That avoids problems with encoding.

So it does thanks. I am not too familiar with python sending bytes that has always worked on "grown up" python.

How would you cope with oring a variable into that?
like

Code: Select all

ser.write(chr(0xC0 | channel ))

Thanks again.

[Roberthh]

In that case it's better to define a bytearray for the command, in which you can assign the values as integers

cmd = bytearray(cmdsize)
cmd[0] = 0xd0 | channel # set the first byte
# set more bytes as required
uart.write(cmd)

[Grumpy_Mike]

Excellent, works like a charm.
Many thanks.