ESP8266 Community Forum

- Mon Sep 14, 2015 9:10 am #29027 Also memory access timing is not predictable.

So I would not recommend (again) to use esp8266 for timing-critical tasks on microsecond level. I've seen several people that tried and failed...

This another world than microcontroller programmers are used to. The hardware is no longer exclusive for the user program and the user program needs to co-exist / run together with the SDK/WLAN code.

- Thu Sep 17, 2015 11:16 am #29259 Would you connect the AVR and the ESP8266 by SPI or UART? I'm asking mostly because of firmware upgrades of the AVR. I know how to write an AVR bootloader if I choose UART - that would cost 1-2KB of AVR flash and 4 pins (RX, TX, AVR reset line and a signal for the bootloader to become active). I know nothing of the ISP firmware upgrade protocol via SPI. Does anybody know if that protocol is timing-critical and should therefore be avoided?

- Thu Sep 17, 2015 11:46 am #29267 I am using UART. SPI isn't quite simple on ESP8266. Make sure you do everything interrupt-driven, on both sides, or you'll lose data. That would be the advantage of SPI.