ESP8266 Community Forum

Thanks for the extra details, sounds straightforward.

I'm sure there are a bunch of tricks that one could do to get around the need to hold the GPIO low - maybe delay the enabling of the MAX transceiver until the ESP has booted somehow, or a delay through a rc/transistor combo or somesuch...

Cheers!

just use an inverter or chose a gpio that isn't also a boot option.

I know this is already an old topic, just want to share:

I also tried the hardware serial and some timing tricks, but finally I had need for more than one UART.

I wrote a small library to use any GPIO-Port for RS485.

Maybe you can use it (pull requests are very welcome!)

https://github.com/plieningerweb/esp8266-software-uart

Congratulations for the great work you have done.

My project is to create a low cost web server ESP8266 (lua) which implements the functions of SDM120c Modbus RTU and allow the reading of the electrical parameters Kwh, V, A, PF, Hz, W etc.

The schematic that attach do you think it can work?
I do not know whether you need to lower the 3.7V to 3.3V.

P.S. Pardon my bad English.