esp8266 and pulse rate sensor

hi all

I'm a new arduino progammer

im trying to get the pulse rate in BPM from the sensor using esp8266 to send an sms if the pulse rate is ubnormal. Can I do this without arduino??

If I use ISR(timer2 .......), it gives me an error


Many different processor boards fall into the Arduino "ecosystem". There's lots of activity in this forum for Teenseys, ESP8266, ESP32, Adafruit boards, etc. It's ridiculous to insist only boards sold by be discussed. IMO, if it can be programmed with the Arduino IDE, then it's fair game.