Best practice for non-blocking delay?

Question

I am looking for best practice to have exact timings when accessing hardware (LCDs, I2C, SPI, etc.).
Any suggestions on learning material or tips are appreciated!

Answer 1

You could use a function that returns the number of milliseconds since boot -millis() in Arduino- and test for timeout in every loop...

The idea in pseudo-code:

loop {
if (millis() - aux >= 1000) { // 1 s elapsed?
do some stuff....
aux = millis();
}

do something...
do something else...
}

Another approach: instead of test every loop for milliseconds elapsed, you could use a timer interrupt (if available)

flag = 0;

loop {
if (flag) {
do some stuff....
flag = 0;
}

do something...
do something else...
}

void timer_interrupt() {
flag = 1;
}

Usually, you use the timer for other counters... you could set the timer to interrupt every 1ms and use variables to count for several events

loop {
if (tmo_stuff_A == 0) {
do some stuff....
tmo_stuff_A = 1000;
}

if (tmo_stuff_B == 0) {
do some stuff....
tmo_stuff_B = 500;
}

do something...
do something else...
}

void timer_interrupt() {
if (tmo_stuff_A > 0)
tmo_stuff_A--;

if (tmo_stuff_B > 0)
tmo_stuff_B--;
}

Last recommendation:

Use finite- state-machines.

An example (mbed and S08, with timer interrupts...in spanish :( )
https://docs.google.com/viewer?a=v&pid=sites&srcid=cGlvaXguZWR1LmFyfHNpc3RlbWFzLWVtYmViaWRvc3xneDozZjkzNjZlMDk2Mzk3Zjlk

Another example with Arduino:
https://code.sololearn.com/cWGKp0lDL1J4/#c

Hope that helps...

Answer 2

By any chance, are you talking about real time programming?

Answer 3

diego Code thank you for the examples. I think, that might be helpful for a lot of people starting with Arduino.

Hatsy Rei I guess your are asking for the OS? FreeRTOS.

I was unsure if I can a quite task specific question: I want to get a SD-Card (without SPI) working on an ESP32 without any Arduino libraries.