For NORVI IIOT devices supporting more than 1 UART channels, a modification of the original drivers are required.
Maximum of 3 UART channels are supplied with NORVI IIOT range controllers. Adhering to following pinout.
UART0 : TX-IO2 / RX-IO4 (Standard UART 0)
UART1 : TX-IO26 / RX-IO25
UART2 : TX-IO1 / RX-IO3
By Default ESP32 drivers installed ; the UART channels are assigned to different GPIO, some GPIOs assigned by default causes ESP32 restart after initializing uart channels.
The default ESP32 UART driver installed must be edited to GPIO used by NORVI IIoT.
1) Locate the HardwareSerial.cpp in the Arduino Installation