UART: Serial2 wont work on Arduino Core v2.0.15

[khryssmar]

Board

ESP32-WROOM-32D

Device Description

Breadboard.

Hardware Configuration

IO17 and IO16 to GPS.

Version

latest master (checkout manually)

IDE Name

Arduino

Operating System

Windows 10

Flash frequency

80Mhz

PSRAM enabled

yes

Upload speed

921600

Description

I am using Serial2 to connect to UBX Neo6m. After 2.0.15, it doesnt work anymore.

Sketch

Serial passthrough

Debug Message

NA

Other Steps to Reproduce

No response

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[SuGlider]

@khryssmar - please provide more information and a simple sketch that can be used to reproduce the issue.

Thanks in advance.

[SuGlider]

A quick test reports that Serial2 is using pins 4 and 25 by default... I'll investigate it.

ets Jun  8 2016 00:22:57

rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0030,len:1344
load:0x40078000,len:13964
load:0x40080400,len:3600
entry 0x400805f0
[     4][D][esp32-hal-cpu.c:244] setCpuFrequencyMhz(): PLL: 480 / 2 = 240 Mhz, APB: 80000000 Hz
[    37][V][esp32-hal-uart.c:330] uartBegin(): UART2 baud(115200) Mode(800001c) rxPin(4) txPin(25)
[    46][V][esp32-hal-uart.c:416] uartBegin(): UART2 not installed. Starting installation
[    56][V][esp32-hal-uart.c:463] uartBegin(): UART2 initialization done.

[SuGlider]

Yes... it was the PR #8800 from 3.0.0 that has been imported into 2.015 by #9176

This breaks the UART pins...

	Name	ESP32	S2	S3	C3
UART0 RX	SOC_RX0	3	44	44	20
UART0 TX	SOC_TX0	1	43	43	21
UART1 RX	RX1	9 -> 26	18 -> 4	15	18
UART1 TX	TX1	10 -> 27	17 -> 5	16	19
UART2 RX	RX2	16 -> 4	--	19	--
UART2 TX	TX2	17 -> 25	--	20	--

[SuGlider]

@khryssmar - a quick workaround would be to initialize Serial2 passing the pins, for example:
Serial2.being(115200, SERIAL_8N1, 16, 17); // baud rate, mode, RxPin, TxPin

[lbernstone]

The Serial2 pins were changed because psram is typically on 16 & 17. With a WROOM module, they are available.

[SuGlider]

It was changed for 3.0.0 as a breaking change.
But for 2.0.x it should reamain the same, not breaking previous sketches.