ESP32-WROOM-32 PWD with millis - arduino

Question

Beginner in Arduino and ESP-32 needs help.
Hello together,
I’m using the Pololu - VNH5019 Motor Driver Carrier to control a 12v motor with an ESP32.
In the following sketch i can speed up and speed down the ramp with delay();.
I tried to archiv the same result with millis(), but until now i could not make it.
What i am missing in my code.
Thanks in advance.
#define MOTOR_IN1 27
#define MOTOR_IN2 16
#define PWMPIN 14
#define frequency 40000
#define resolutionbit 8
const unsigned long eventInterval = 30;
unsigned long previousTime = 0;
void setup() {
pinMode(MOTOR_IN1, OUTPUT);
pinMode(MOTOR_IN2, OUTPUT);
ledcAttachPin(PWMPIN, 0); // assign the speed control PWM pin to a channel
ledcSetup(0, frequency, resolutionbit);
}
void loop() {
//with_delay();
with_millis();
}
//------------------------------------------
void with_delay() {
// set direction
digitalWrite(MOTOR_IN1, HIGH);
digitalWrite(MOTOR_IN2, LOW);
// ramp speed up
for (int i = 0; i <= 255; i++) {
ledcWrite(0, i);
delay(30);
}
// ramp speed down
for (int i = 255; i >= 0; i--) {
ledcWrite(0, i);
delay(30);
}
}
//-------------------------------------------
void with_millis() {
unsigned long currentTime = millis();
if (currentTime - previousTime >= eventInterval) {
digitalWrite(MOTOR_IN1, HIGH);
digitalWrite(MOTOR_IN2, LOW);
for (int i = 0; i <= 255; i++) {
ledcWrite(0, i);
previousTime = currentTime;
}
}
if (currentTime - previousTime >= eventInterval) {
digitalWrite(MOTOR_IN1, HIGH);
digitalWrite(MOTOR_IN2, LOW);
for (int i = 255; i >= 0; i--) {
ledcWrite(0, i);
previousTime = currentTime;
}
}
}

Answer 1

Your problem is that the program gets stuck in the for loop.
You need to also create direction variable so the program that knows which if statement to execute.
You need to create some other logic that will increase the i variable without stopping the whole program.
The code:
//Initialize the i variable globaly:
int i = 0;
bool direction = 0;
//Your function:
void with_millis() {
unsigned long currentTime = millis();
if ((currentTime - previousTime >= eventInterval) && direction == true) {
digitalWrite(MOTOR_IN1, HIGH);
digitalWrite(MOTOR_IN2, LOW);
i++;
if (i <= 255) {
ledcWrite(0, i);
previousTime = currentTime;
} elif (i > 255) {
i = 0;
direction = false;
}
}
if ((currentTime - previousTime >= eventInterval) && direction == false) {
digitalWrite(MOTOR_IN1, LOW);
digitalWrite(MOTOR_IN2, HIGH);
i++;
if (i <= 255) {
ledcWrite(0, i);
previousTime = currentTime;
} elif (i > 255) {
i = 0;
direction = true;
}
}
}