Timer on ESP32 hangs the chip if used with WiFi and a too fast rate for the Timer (ex 15mS), not happening on ESP8266.

[profjmer]

On a ESP8266 I have an app, that is running an FSM by a Timer each 100uSec. (running fine with: Wifi, webserver, i2c, spi ...)

On an ESP32 a single bit toggle by a Timer can work at the same rate in Basic_Blink, but in Basic_Wifi sample, a rate faster than 15mS will hang the system.

Here is an extract of the test code:

int i;
IRAM_ATTR void systick()
{
	if(i++>9){
		digitalWrite(22,!digitalRead(22));  // this is an LED on my ESP32 Board TTGO V1.3
		i=0;
	}
}

in void init()
pinMode(22,OUTPUT);
pulse_timer.initializeMs<15>(systick).start();

ESP8266 has only one core and is performing better with Timer and WiFi
Esp32 has two cores, but Timer seems to interfere with WiFi at a rate too fast.
Is it something that can be improved in ESP32 ? (by not using the same core that WiFi uses ? or else)

[mikee47]

Fast timers are very inefficient on the esp32 due to the interrupt and software servicing overhead. Perhaps look for a way to use the hardware directly, e.g. LEDC or other modules.

Sming builds with CONFIG_FREERTOS_UNICORE=y by default. See #2916 et. al.

[mikee47]

NB. Are you using HardwareTimer? This has a lower software overhead as the callback is invoked in interrupt context. Software timers use the task queue which slows things down.

[mikee47]

See also #2445 (comment)

[mikee47]

@profjmer Be interested to hear about any solution you come up with for this.