invert status never reset on serial0 after having been set to invert once

[mha1]

Board

esp32-s3-devkitc-1

Device Description

esp32-s3-devkitc-1

Hardware Configuration

Pin 3 (UART0 TX) and GND are connected to a logic analyzer.

Please refer to the test code below. Expected output is an alternating output of non-inverted and inverted serial signals.

For serial0 the logic analyzer trace shows non-inverted, inverted, inverted, ... which is wrong.

running the test code on serial1 shows the expected behavior.

changing arduino-esp32/cores/esp32/esp32-hal-uart.c fixes the problem however it is unclear why the serial0 and serial1 behave differently.

arduino-esp32/cores/esp32/esp32-hal-uart.c

Lines 517 to 520 in 99750cd

	if (retCode && inverted) {
	// invert signal for both Rx and Tx
	retCode &= ESP_OK == uart_set_line_inverse(uart_nr, UART_SIGNAL_TXD_INV | UART_SIGNAL_RXD_INV);
	}

.

if (retCode && inverted) {
  // invert signal for both Rx and Tx
  retCode &= ESP_OK == uart_set_line_inverse(uart_nr, UART_SIGNAL_TXD_INV | UART_SIGNAL_RXD_INV);
}
else
{  
  // reset invert
  retCode &= ESP_OK == uart_set_line_inverse(uart_nr, UART_SIGNAL_INV_DISABLE);
}

Version

latest master (checkout manually)

IDE Name

VSCode/platformio

Operating System

Windows 10

Flash frequency

40Mhz

PSRAM enabled

yes

Upload speed

921600

Description

It should be possible to change serial transmission from non-inverted to inverted and back to non-inverted. This doesn't work on serial0. Please refer to the test code I attached.

Sketch

#include <Arduino.h>
#include <HardwareSerial.h>

HardwareSerial serial(0);   // use serial(1) for comparison

void setup() {}

void loop() {
  serial.begin(115200, SERIAL_8N1, 3, 1, false);
  serial.write("hello");
  serial.flush();
  serial.end();

  serial.begin(115200, SERIAL_8N1, 3, 1, true);
  serial.write("hello");
  serial.flush();
  serial.end();
}

Debug Message

see attached logic analyzer trace

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]

Yes, confirmed. Thank for the issue report, @mha1!
I'll add a PR as suggested.

[SuGlider]

About why Serial and Serial0 behave differently, I'll try to figure it out.

[mha1]

@SuGlider any news?

[SuGlider]

I'll work on it today.

[SuGlider]

@mha1 - What is the Arduino Core version that you have used to detect that Serial0 can't invert / revert the RX/TX signals?

[mha1]

framework-arduinoespressif32 @ 3.20011.230801 (2.0.11)

[SuGlider]

Ok... There are a few bugs with Serial and 2.0.11. Please try 2.0.17 instead.
Or try 3.0.2.

The PR will fix it for 3.0.3 and I can apply it in the Arduino release/v2.x branch.

[SuGlider]

framework-arduinoespressif32 @ 3.20011.230801 (2.0.11)

This explains why it works with Serial1 and not with Serial0.
Many bug fixes within HardwareSerial and ESP32 UART HAL were applied after 2.0.11
It may be necessary to update your Arduino Core code, manually or using some PlatformIO setup.

[mha1]

"Ok... There are a few bugs with Serial and 2.0.11. Please try 2.0.17 instead.
Or try 3.0.2."

You mean other bugs besides the invert one, aren't you?
You're fixing the invert bug with 3.0.3, correct?

[SuGlider]

"Ok... There are a few bugs with Serial and 2.0.11. Please try 2.0.17 instead. Or try 3.0.2."

You mean other bugs besides the invert one, aren't you? You're fixing the invert bug with 3.0.3, correct?

yes, correct.

[SuGlider]

@mha1 - You can copy the HardSerial and HAL from release/v2.x into your local Arduino Core files.

https://github.com/espressif/arduino-esp32/blob/release/v2.x/cores/esp32/HardwareSerial.cpp
https://github.com/espressif/arduino-esp32/blob/release/v2.x/cores/esp32/HardwareSerial.h
https://github.com/espressif/arduino-esp32/blob/release/v2.x/cores/esp32/esp32-hal-uart.c
https://github.com/espressif/arduino-esp32/blob/release/v2.x/cores/esp32/esp32-hal-uart.h

After that, fix manually the Inversion...