ESP8266 Community Forum

- Sat Nov 24, 2018 4:41 pm #79256 On stackexchange they also suggested using a power supply reset controller like the TI TVL803S. The Wemos D1 Mini doesn't seem to have one integrated. Is it worth including this? If there's a power cut then I want the controllers to start in a known state when power is restored without any intervention from me.

Normally when the RPi is up and running again it should instruct the controllers what heating mode to be in, but I will set a default mode in the ESP8266 software which will be used until the RPi is running.

- Sun Nov 25, 2018 4:30 pm #79269 My previous reply hasn't appeared, but anyway... I've investigated the power-on-reset controller and I don't think the Wemos D1 Mini board needs one. These docs describe the power-on sequence (section 4.6 in https://www.espressif.com/sites/default/files/documentation/esp8266_hardware_design_guidelines_en.pdf and 1.4.2 in https://www.espressif.com/sites/default/files/documentation/esp8266_hardware_design_guidelines_en.pdf) and the board has a 12k pull-up resistor on CH_EN (https://wiki.wemos.cc/_media/products:d1:sch_d1_mini_v3.0.0.pdf) which I think delays activation until after EXT_RSTB is activated internally in the ESP8266.

Second thing. Section 4.3 of https://www.espressif.com/sites/default/files/documentation/esp8266_hardware_design_guidelines_en.pdf and 1.4.1 of https://www.espressif.com/sites/default/files/documentation/esp8266_hardware_design_guidelines_en.pdf say that a minimum 500mA supply is needed. The first doc also says that DIO may draw up to 200mA. So does this mean a 700mA supply is needed? Or do these peaks not both happen at the same time?