Can I send any CC values with Midi unit/Core3s/UIflow 2.0?

kcuk220

Hi everyone,

I have received with my core3s and midi unit recently and I want to start my first project with UIflow 2.0. My project is about sending midi messages to a synthesizer in order to make a sequence of sound, as simple as that.

UIflow made it easy to send note message and some other messages. However, I want to be able to send less common messages such as for Portamento (CC = 5) and I don't know how to do that.

I am a newbie and it is possible that I have just asked a dumb question. Any useful information would be appreciated!

Thank you

yuyun2000

@kcuk220 No dumb questions at all! To send Portamento Time (CC 5) with your M5Stack Core3S and MIDI Unit in UIFlow 2.0, you'll need to use the cmd_write method to send raw MIDI control change messages. Here's how:
Step 1: Understand the MIDI CC Message Structure
Portamento Time (CC 5) uses this MIDI message format:Bn 05h cc

Bn: Status byte (B = Control Change, n = MIDI channel 0-15 → hex 0-F)
05h: CC number (5 for Portamento Time)
cc: Value (0-127, where 0 = fastest portamento, 127 = slowest)

Step 2: UIFlow 2.0 Implementation

Initialize the MIDI Unit (if not already done):Use the "MIDI Unit" block under "Units" to set up the MIDI Unit with your UART port (e.g., Port A).

Send Portamento CC Message using cmd_write:The cmd_write method accepts a list of MIDI bytes. For Portamento Time on Channel 1 (hex 0), with a value of 64 (medium speed):

Bytes = [0xB0, 0x05, 0x40]
0xB0 = Channel 1 (0xBn where n=0), Control Change
0x05 = CC number 5 (Portamento Time)
0x40 = Value 64 (hex for 64)

Example Code (Blockly & Python)
Blockly:

Add a "MIDI Unit" → "cmd_write" block.
Set the input to [176, 5, 64] (decimal equivalent of 0xB0, 0x05, 0x40).

Python (Advanced):
from m5stack import *
from m5ui import *
from uiflow import *
import unit

Initialize MIDI Unit (adjust port if needed)

midi = unit.get(unit.MIDI, unit.PORTA)

Send Portamento Time (CC 5) on Channel 1, value 64

midi.cmd_write([0xB0, 0x05, 0x40]) # B0=Ch1, 05=CC5, 40=64

Key Notes:

Channel Adjustment: Change the first byte to target different channels. For example:
Channel 2 → 0xB1 (hex) or 177 (decimal)
Channel 10 (drums) → 0xB9 (hex) or 185 (decimal).

Value Range: Use 0-127 for cc (e.g., 0x00 = 0 = fastest, 0x7F = 127 = slowest).

Verification
Test with a MIDI monitor (e.g., MIDI-OX on Windows, MIDI Monitor on macOS) to confirm the CC 5 message is received. Most synths require Portamento to be enabled (via CC 65, "Portamento On/Off") before CC 5 takes effect.
https://chat.m5stack.com/