ESP8266 Community Forum

Posted: **Thu Oct 06, 2016 3:50 am**

Dear all,

I just saw that toggling the GPIO0 takes around 3.28us. Could someone tell me why? The CPU frequency is 80MHz right? This would give a clock cycle of 12.5ns.

I tried this on an ESP-14 with the BasicOTA.ino running in background but that should not bother it too much.

Code: Select all

pinMode(0, OUTPUT);
digitalWrite(0, HIGH);
digitalWrite(0, LOW);
digitalWrite(0, HIGH);
digitalWrite(0, LOW);
digitalWrite(0, HIGH);
digitalWrite(0, LOW);

UPDATE: Ok, for some reason with the same code now I get 420ns for a pin toggle. This is still far to slow. Wifi and OTA is turned off, basically I use an empty sketch now.

Please someone help me.

Posted: **Thu Oct 06, 2016 12:19 pm**

Maybe I got something completely wrong but I do not get why the ESP8266 is so slow with pin actions.

Why is there such a long delay after switching the pin to INPUT?
Why is there also a long delay after switchting the pin to OUTPUT again?

What do I miss???

Code: Select all

pinMode(0, OUTPUT);
digitalWrite(0, LOW);
digitalWrite(0, HIGH);
digitalWrite(0, LOW);
digitalWrite(0, HIGH);
digitalWrite(0, LOW);
digitalWrite(0, HIGH);
digitalWrite(0, LOW);
digitalWrite(0, HIGH);
digitalWrite(0, LOW);
pinMode(0, INPUT_PULLUP);
pinMode(0, OUTPUT);
digitalWrite(0, HIGH);
digitalWrite(0, LOW);
digitalWrite(0, HIGH);
digitalWrite(0, LOW);
digitalWrite(0, HIGH);
digitalWrite(0, LOW);
digitalWrite(0, HIGH);
digitalWrite(0, LOW);
digitalWrite(0, HIGH);

Posted: **Thu Oct 06, 2016 11:47 pm**

Everyone with Arduino have nearly complete source code so look into core_esp8266_wiring_digital.c and You will see...
Short story: If You want fast GPIO change (not using GPIO16), use GPOS/GPOC instead of digitalWrite()...

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