SIM800L cannot init

[PeteKnight]

The ESP8266 does have one and a half serial ports. The ‘half a port’ is Tx only, which makes it ideal for serial debug via an FTDI adapter.

Obviously wired software updates (as opposed to OTA) still use the primary serial port, so the SIM800 would need to be disconnected to allow new firmware to be uploaded via the primary UART.

More here:

How to use 2 serial ports or more in NodeMCU

How to use 2 serial ports or more in NodeMCU I recently made a mini car, using GPS module and 433m wireless module. Blynk recently added GPS capabilities to the app. But the serial port does not seem to share, I hope to add a new serial port for GPS module. This is a simple wiring diagram [5iXFZWz]

Pete.