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nodemcu / nodemcu-firmware

Lua based interactive firmware for ESP8266, ESP8285 and ESP32
https://nodemcu.readthedocs.io
MIT License
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UART1 not usable from lua because NUM_UART is 1 in app/platform/cpu_esp8266.h #1907

Closed horsteff closed 7 years ago

horsteff commented 7 years ago

The ESP8266 has two uarts, but only UART0 is usable from lua. According to the code in uart module and driver files UART1 seems well supported, but using it from lua is currently impossible due to the check for supported uart ids in app/modules/uart.c (MOD_CHECK_ID(uart, id), checks id with NUM_UART which is defined as 1 in app/platform/cpu_sp8266.h).

I used the docker NodeMCU build to create a firmware image from master branch but with NUM_UART defined as 2 in app/platform/cpu_esp8266.h and used it successfully to transmit data from lua code via TXD1 on an ESP-12 module. Is there any reason not to define NUM_UART as 2?

Expected behavior

uart.setup(1, ... uart.write(1, ... Should setup UART1 and write to TXD1

Actual behavior

uart.setup(1, ... uart.write(1, ... Both raise "uart 1 does not exist".

NodeMCU version

master branch

Hardware

tested with ESP-12 module

dnc40085 commented 7 years ago

If UART 1 were exposed, it would be transmit only since U1_RXD is also SD_D1, which is one of the data lines to the internal flash.

I don't see a reason why it couldn't be used as a transmit only serial interface or a debug output though.

SpComb commented 7 years ago

:+1: for this

I've been running a patched 1.5.4.1 firmware with #define NUM_UART 2 for a while now, using uart.setup(1, ...)for DMX output on the second UART: https://github.com/nodemcu/nodemcu-firmware/compare/master...SpComb:dmx-uart2#diff-90eef6db68568af326362418e2196fdeR14

AFAIK this just prevents using the second UART for debugging output from the ESP SDK?

devsaurus commented 7 years ago

PR merged, thanks guys!