I am working on a sketch to read data from the HAN (MBus) port on my smart electricity meter. From the meter, through an MBUS to TTL converter, I get serial data using 8E1.
SoftwareSerial is not compatible with 8E1, and Serial.swap() has not given me the wanted results. Then I tried using UART0 which is connected to GPIO1 (TX) and GPIO3 (RX), and got data from the meter OK.
However, now I need to disconnect the serial connection from the meter when new code is uploaded. This is because the same UART is used to upload firmware to the ESP8266.
On the NodeMCU v3 board UART0 is Connected to the USB/Serial converter via two 470 ohm resistors. What I would like is to make a selector where these can be disconnected and connected at will so that the TX/RX pins on the board can have a clean connection to the outside world.
I have not managed to find a components layout for the board, and I have some trouble locating these resistors. Can anyone help finding these resistors on the board?
Thanks, Helge.