Arduino 16-step sequencer - Notes not in sync - arduino

Question

I am using the following code for my arduino mega to send midi clock out to my drum machine & synth.
The problem appears when I also try to send midi notes exactly on the 'beat'.
Only the first note is perfectly synced, the rest of them are out of sync and you can hear it.
Is there any apparent flaw in the code?
// METRONOME
#include <MIDI.h>
#define LED1PIN 13
#define LED4PIN 7
#define SWITCHAPIN 5
#define SWITCHBPIN 2
MIDI_CREATE_INSTANCE(HardwareSerial, Serial1, MIDI);
void setup() {
pinMode(LED1PIN, OUTPUT);
pinMode(LED4PIN, OUTPUT);
pinMode(SWITCHAPIN, INPUT);
pinMode(SWITCHBPIN, INPUT);
digitalWrite(SWITCHAPIN, HIGH);
digitalWrite(SWITCHBPIN, HIGH);
MIDI.begin(MIDI_CHANNEL_OMNI);
Serial.begin(9600);
Serial.println("Setting up");
}
unsigned long nextClockTime = 0;
int clockDelay = 20;
int tickCount = 0;
byte running = 0;
int pula = 0;
int currentStep = 1;
int lastPulse = 0;
int currPulse = 0;
int nextTickCount = 0;
typedef struct {
int noteNumber;
int velocity;
int noteLength;
bool enabled;
}
Step;
Step stepData[100];
void loop() {
stepData[0].enabled = true;
stepData[0].velocity = 127;
stepData[0].noteNumber = 40;
stepData[23].enabled = true;
stepData[23].velocity = 127;
stepData[23].noteNumber = 40;
stepData[47].enabled = true;
stepData[47].velocity = 127;
stepData[47].noteNumber = 40;
stepData[71].enabled = true;
stepData[71].velocity = 127;
stepData[71].noteNumber = 40;
stepData[95].enabled = true;
stepData[95].velocity = 127;
stepData[95].noteNumber = 40;
MIDI.read();
unsigned long milliseconds = millis();
if (milliseconds > nextClockTime) {
if (running)
MIDI.sendRealTime(MIDI_NAMESPACE::Clock);
nextClockTime = milliseconds + clockDelay;
nextTickCount = tickCount + 1;
if (tickCount == 0) {
if (stepData[tickCount].enabled) {
MIDI.sendNoteOn(stepData[tickCount].noteNumber, stepData[tickCount].velocity, 1);
Serial.print("STEP ENABLED: ");
Serial.println(tickCount);
}
}
if (tickCount == 23) {
if (stepData[tickCount].enabled) {
MIDI.sendNoteOn(stepData[tickCount].noteNumber, stepData[tickCount].velocity, 1);
Serial.print("STEP ENABLED: ");
Serial.println(tickCount);
currPulse = millis(); //1500
Serial.println(currPulse - lastPulse); //1500-500
lastPulse = currPulse;
}
}
if (tickCount == 47) {
if (stepData[tickCount].enabled) {
MIDI.sendNoteOn(stepData[tickCount].noteNumber, stepData[tickCount].velocity, 1);
Serial.print("STEP ENABLED: ");
Serial.println(tickCount);
currPulse = millis();
Serial.println(currPulse - lastPulse);
lastPulse = currPulse;
}
}
if (tickCount == 71) {
if (stepData[tickCount].enabled) {
MIDI.sendNoteOn(stepData[tickCount].noteNumber, stepData[tickCount].velocity, 1);
Serial.print("STEP ENABLED: ");
Serial.println(tickCount);
currPulse = millis();
Serial.println(currPulse - lastPulse);
lastPulse = currPulse;
}
}
if (tickCount == 95) {
if (stepData[tickCount].enabled) {
//MIDI.sendNoteOn(stepData[tickCount].noteNumber, stepData[tickCount].velocity, 1);
Serial.print("STEP ENABLED: ");
Serial.println(tickCount);
currPulse = millis();
Serial.println(currPulse - lastPulse);
lastPulse = currPulse;
}
nextTickCount = 0;
}
tickCount = nextTickCount;
} else if (digitalRead(SWITCHBPIN) == LOW) {
if (running) {
MIDI.sendRealTime(MIDI_NAMESPACE::Stop);
running = 0;
digitalWrite(LED4PIN, LOW);
}
} else {
clockDelay = analogRead(A0) / 10;
}
if (pula == 0) {
if (!running) {
MIDI.sendRealTime(MIDI_NAMESPACE::Start);
tickCount = 0;
running = 1;
digitalWrite(LED4PIN, HIGH);
pula = 1;
}
}
}

Answer 1

The beats are not evenly spaced. 24 - 1 is 23, 48 - 24 is 24 etc.
A simple fix would be to put your first beat on 0 not 1. Instead of incrementing tickCount, set a variable nextTickCount to tickCount +1, and assign it to tickCount at the end of the if (milliseconds > nextClockTime) { conditional bracket.
Also, set nextTickCount to 0 when tickCount reaches 95, but don't play any note (it will be played on the 0 beat )