Arduino Pro Mini programming MIDI

Hardware/software :

-Arduino Pro-Mini/AT mega 328P
-FTDI232 to program the pro-mini
-Windows 10
Arduino IDE 1.8.15

I'm trying to build a Midi Sync box to sync the Jam Man looper with midi
because they don't natively recieve or transmit midi they. Digitech uses some proprietary
Pulse/Signal. So this box is necessary to use the Jam Man looper with midi.
found this code on-line somewhere it says it can be modified to work with the ATmega arduino
was wondering if anyone could help me modify the code to work for what i'm trying to use it for.
and also need help programming the Arduino Pro-Mini

This sketch listens to incoming midi clock messages on port RX and pulses output tempo_pin each quarter note,
i.e. every 24th clock tick
Written for Attiny85 but can be modified for other Atmega, Attiny MCU's
IMPORTANT! Don't use pins RX, TX for anything else other than the SoftwareSerial library
more details, schematics, etc.. here: Digitech JamMan stereo MIDI sync | ambinaut
#define F_CPU 8000000UL //Define the speed the clock is running at. Used for the delay.h functions

#include <avr/io.h> //Include the headers that handles Input/Output function for AVR chips
#include <util/delay.h> //Include the headers that allow for a delay function
#include <SoftwareSerial.h> //Arduino Software Serial library
#include <avr/sleep.h> // Lib for sleep modes
#include <avr/interrupt.h> //Lib for interrupts

#define tempo_pin 1 //Physical pin 6, or PB1 on the Attiny85

byte midi_msg = 0; //stores incoming midi messages, only 1 byte needed, real time msgs are one byte long
byte clockpulse = 0; //stores current midi clock tick number
unsigned long last_midi_event_time = 0; //time of the last incoming midi event

SoftwareSerial mySerial(3, 4); // RX, TX Physical pins 2, 3

void init_io(void)
DDRB |= _BV(tempo_pin); //set tempo_pin and test_led as outputs
PORTB &= ~(_BV(tempo_pin)); //set the pins to LOW

int main(void)

while (1) {  //endless loop

	if (mySerial.available()) {
		midi_msg =;
		last_midi_event_time = millis();
		midi_clk_to_pulse(); //see below			
	//if there's no more incoming midi for longer than 1000ms, set tempo_pin LOW
	else   {
		unsigned long current_time = millis() – last_midi_event_time;
		if (current_time > 1000){		
			midi_msg = 0xFC; //midi stop message
			last_midi_event_time = 0;
} //END while (1) – endless (main) loop


void midi_clk_to_pulse(){

switch(midi_msg) {

	case 0xFC: //midi stop message
		clockpulse = 0;
		PORTB &= ~(_BV(tempo_pin)); //turns tempo_pin off
	case 0xFA: //midi start message
		clockpulse = 0;
		PORTB &= ~(_BV(tempo_pin)); //turns tempo_pin off
	case 0xF8: //midi clock pulse
		clockpulse = clockpulse + 1;
		switch (clockpulse){
			case 1:
			PORTB |= (_BV(tempo_pin)); //tempo_pin HIGH
			case 8:
			PORTB &= ~(_BV(tempo_pin)); //tempo_pin LOW
			case 24: // second quarter begin
			PORTB |= (_BV(tempo_pin)); //tempo_pin HIGH
			case 32:
			PORTB &= ~(_BV(tempo_pin)); //tempo_pin LOW
			case 48: // third quarter begin, middle of the measure
			PORTB |= (_BV(tempo_pin)); //tempo_pin HIGH
			case 56:
			PORTB &= ~(_BV(tempo_pin)); //tempo_pin LOW
			case 72: //fourth quarter begin
			PORTB |= (_BV(tempo_pin)); //tempo_pin HIGH
			case 80:
			PORTB &= ~(_BV(tempo_pin)); //tempo_pin LOW
			case 96:
			clockpulse = 0; // resets the clock pulse counter, 96 pulses = 1 measure in 4/4
		break; //END case 0xF8:
	} // END switch (clockpulse)
} // END switch(midi_msg)

} //END midi_clk_to_pulse()

void sleep() {

GIMSK |= _BV(PCIE);                     // Enable Pin Change Interrupts
PCMSK |= _BV(PCINT2);                   // Use PB2 as interrupt pin
ADCSRA &= ~_BV(ADEN);                   // ADC off
set_sleep_mode(SLEEP_MODE_PWR_DOWN);    // replaces above statement

sleep_enable();                         // Sets the Sleep Enable bit in the MCUCR Register (SE BIT)
sei();                                  // Enable interrupts
sleep_cpu();                            // sleep

cli();                                  // Disable interrupts
PCMSK &= ~_BV(PCINT2);                  // Turn off PB2 as interrupt pin
sleep_disable();                        // Clear SE bit
ADCSRA |= _BV(ADEN);                    // ADC on

sei();                                  // Enable interrupts
} // sleep


Read the documentation & follow the instructions.

Thats all I can offer as you have not posted anything usefull.


Which .hex files? Which documentation?

If you're referring to MIDI over USB firmware, this is not possible on the Pro Mini, it can only do serial MIDI.

1 Like

Don't post pictures of text!

What com port is your programmer set up on?

I'm not sure

Sorry :neutral_face: I didn't know

@davroxxx Welcome to the forum!

People here are glad to help, but expect you to read and follow the forum instructions.