[EN] ESP32 machine.Timer

This article discusses the use of 4 timers of the ESP32 to be used to run the program when it meets the specified time. Difference Between Using Timer and Delay time.sleep()/time.sleep_ms()/time.sleep_us() is that time delay is a loop to allow the processor to spend time looping to complete the specified amount of time whereas the timer uses the principle of having a function run every time a specified time is reached, so while a timer does not call a function to execute the processor has idle time for other processing, and unlike interrupts, it is a timer interrupt instead of a pin state interrupt connected to an external circuit.

Timer

ESP32 timers or timers have two groups, each containing two sub-hardware timers, four of which are 64-bit timers running 16-bit pre-scalars and 64-bit up/down counters supporting automatic reloading

Calling the timer class for the ESP32 microcontroller is done by calling the Timer class under the machine class as follows:

from machine import Timer

The creation of a timer object has the following form of declaration, timer number is the sequence number of the timer to be used which are the values 0, 1, 2, and 3.

object = Timer( timer_number )

When there is a timer object available, configure the timer behavior with the init( ) command as follows.

object.init( period, mode, callback )

where

period is the operating time of the timer. It is in milliseconds.
mode is a timer working mode that has 2 working modes as follows.
- Timer.ONE_SHOT for being executed only once.
- Timer.PERIODIC for calling the callback function every specified period.
callback is the function that is called when the timer runs.

To cancel holding the timer can be done with the following command.

object.deinit( )

Example code demoTimer0.py allows the speaker to emit a sound once after a set time of 2 seconds by connecting the speaker to the GPIO25 pin. The program will emit a beep even with a 5 seconds delay.

###########################################
# demoTimer0.py
# (C) 2021, JarutEx
# https://www.jarutex.com
###########################################
from machine import Timer
from machine import Pin
from time import sleep_ms

def beep(x):
    spkPin = Pin( 25, Pin.OUT )
    spkPin.on()
    sleep_ms(50)
    spkPin.off()

try:
    tmr0 = Timer(0)
except:
    print("cannot construct Timer(0)!")
try:
    tmr0.init( period=2000, mode=Timer.ONE_SHOT, callback=beep)
except:
    print("cannot init()!")
sleep_ms(5000)
if (tmr0):
    tmr0.deinit()

Example code demoTimer1.py changes the vocalization pattern to occur every 2 seconds by setting the mode to Timer.PERIODIC and the program has 2 beeps, the first after 2 seconds, the second when entering the 4th second, after 1 second it is the end of the 5 seconds delay and the program ends.

###########################################
# demoTimer1.py
# (C) 2021, JarutEx
# https://www.jarutex.com
###########################################
from machine import Timer
from machine import Pin
from time import sleep_ms

def beep(x):
    spkPin = Pin( 25, Pin.OUT )
    spkPin.on()
    sleep_ms(50)
    spkPin.off()

try:
    tmr0 = Timer(0)
except:
    print("cannot construct Timer(0)!")
try:
    tmr0.init( period=2000, mode=Timer.PERIODIC, callback=beep)
except:
    print("cannot init()!")
sleep_ms(5000)
if (tmr0):
    tmr0.deinit()

Conclusion

From this article, you will find that implementing a timer can be set to run the function at a specific time or run at a preset time. This is considered a type of interrupt but from a source of four available timers allowing programmers to use the chip more efficiently. Finally, have fun with programming.

References

(C) 2020-2021, By Jarut Busarathid and Danai Jedsadasthitikul
Updated 2021-10-23