UART communication broken on ESP32-WROOM after commit 155a9860c (uart_set_pin refactor) - (continued #12277)

[Bascy]

Board

ESP32 Dev module

Device Description

Using a ESP32 development board, containing a ESP-WROOM-32

Hardware Configuration

Hardwired GPIO_12 to GPIO_25 and GPIO_15 to GPIO_26

Version

v3.3.6

Type

Bug

IDE Name

VSCOde

Operating System

Windows 11

Flash frequency

40MHz

PSRAM enabled

no

Upload speed

460800

Description

After PR #12201 (commit 155a986), UART communication is broken on ESP32-WROOM-32.

Working version: b929eb4
Broken version: 155a986

Issue: When using Serial1 and Serial2 with custom GPIO pins, no data is received.

Reproduction:

1. Use the test case in this issue (two UARTs with cross-connected TX/RX)
2. Expected: Messages pass through, success rate ~100%
3. Actual: No data received, success rate 0%

The problem appears to be that uart_set_pin() is called separately for each pin
(RX, TX, CTS, RTS) instead of together as in the old _uartInternalSetPin() function.

Minimal test case: [Attach your test_with_diagnostics.cpp or main.cpp]

Sketch

++
// Diagnostic version of the UART test to help identify the root cause
// Replace src/main.cpp with this to get more detailed information

#include <Arduino.h>
#include <esp32-hal-uart.h>
#include "HWCDC.h"

#define SERIAL1_TX 12
#define SERIAL1_RX 15
#define SERIAL2_TX 25
#define SERIAL2_RX 26

#define TEST_INTERVAL 5000  // ms between tests
#define BAUD_RATE 115200
#define TEST_TIMEOUT 1000   // ms to wait for response

unsigned long serial1ToSerial2Success = 0;
unsigned long serial1ToSerial2Fail = 0;
unsigned long serial2ToSerial1Success = 0;
unsigned long serial2ToSerial1Fail = 0;

unsigned long lastTestTime = 0;
bool testSerial1ToSerial2 = true;

void printUARTStatus(const char* name, HardwareSerial &serial) {
    Serial.printf("\n=== %s Status ===\n", name);
    Serial.printf("  Bytes available to read: %d\n", serial.available());
}

void printStats() {
    Serial.println("\n========== Serial Test Statistics ==========");
    Serial.printf("Serial1 -> Serial2: %lu passed, %lu failed (%.1f%% success)\n",
                  serial1ToSerial2Success,
                  serial1ToSerial2Fail,
                  (serial1ToSerial2Success + serial1ToSerial2Fail) > 0
                    ? (100.0 * serial1ToSerial2Success / (serial1ToSerial2Success + serial1ToSerial2Fail))
                    : 0.0);
    Serial.printf("Serial2 -> Serial1: %lu passed, %lu failed (%.1f%% success)\n",
                  serial2ToSerial1Success,
                  serial2ToSerial1Fail,
                  (serial2ToSerial1Success + serial2ToSerial1Fail) > 0
                    ? (100.0 * serial2ToSerial1Success / (serial2ToSerial1Success + serial2ToSerial1Fail))
                    : 0.0);
    Serial.println("============================================\n");
}

bool testSerialPair(HardwareSerial &sender, HardwareSerial &receiver, const char* direction) {
    static unsigned long testCounter = 0;
    testCounter++;
    String testMessage = String("TEST:") + testCounter + ":" + millis();

    Serial.printf("[%s] Sending: %s\n", direction, testMessage.c_str());

    // Clear receiver buffer
    while (receiver.available()) {
        receiver.read();
    }

    // Send test message
    sender.println(testMessage);
    sender.flush();

    // Debug: Check UART status after sending
    Serial.printf("[%s] After flush, checking receiver status...\n", direction);
    if (strcmp(direction, "S1->S2") == 0) {
        printUARTStatus("Serial2 (receiver)", receiver);
    } else {
        printUARTStatus("Serial1 (receiver)", receiver);
    }

    // Wait for response
    unsigned long startTime = millis();
    String received = "";
    bool success = false;
    int bytesRead = 0;

    while (millis() - startTime < TEST_TIMEOUT) {
        if (receiver.available()) {
            char c = receiver.read();
            bytesRead++;
            if (c == '\n') {
                break;
            }
            if (c != '\r') {
                received += c;
            }
        }
        delay(1);
    }

    // Verify received message
    Serial.printf("[%s] Read %d bytes, received: '%s'\n", direction, bytesRead, received.c_str());

    if (received == testMessage) {
        Serial.printf("[%s] SUCCESS - Message verified\n", direction);
        success = true;
    } else {
        Serial.printf("[%s] FAILED - Expected: %s, Got: %s\n",
                      direction, testMessage.c_str(),
                      received.length() > 0 ? received.c_str() : "(nothing)");
        success = false;
    }

    return success;
}

void setup() {
    delay(2000);

    Serial.begin(115200);
    Serial.println();
    Serial.println();
    Serial.println("========================================");
    Serial.println("  ESP32 Serial Port Communication Test");
    Serial.println("  (Diagnostic Version)");
    Serial.println("========================================");
    Serial.println();

    Serial.println("Initializing Serial1...");
    Serial1.begin(BAUD_RATE, SERIAL_8N1, SERIAL1_RX, SERIAL1_TX);
    Serial.printf("Serial1 initialized: TX=GPIO%d, RX=GPIO%d, Baud=%d\n", SERIAL1_TX, SERIAL1_RX, BAUD_RATE);
    printUARTStatus("Serial1", Serial1);

    Serial.println("\nInitializing Serial2...");
    Serial2.begin(BAUD_RATE, SERIAL_8N1, SERIAL2_RX, SERIAL2_TX);
    Serial.printf("Serial2 initialized: TX=GPIO%d, RX=GPIO%d, Baud=%d\n", SERIAL2_TX, SERIAL2_RX, BAUD_RATE);
    printUARTStatus("Serial2", Serial2);

    Serial.println();
    Serial.println("Connect the following pins together:");
    Serial.printf("  Serial1 TX (GPIO%d) -> Serial2 RX (GPIO%d)\n", SERIAL1_TX, SERIAL2_RX);
    Serial.printf("  Serial1 RX (GPIO%d) -> Serial2 TX (GPIO%d)\n", SERIAL1_RX, SERIAL2_TX);
    Serial.println();
    Serial.println("Starting tests in 3 seconds...");
    Serial.println();

    delay(3000);
}

void loop() {
    unsigned long currentTime = millis();

    if (currentTime - lastTestTime >= TEST_INTERVAL) {
        lastTestTime = currentTime;

        if (testSerial1ToSerial2) {
            Serial.println("\n--- Testing Serial1 -> Serial2 ---");
            bool success = testSerialPair(Serial1, Serial2, "S1->S2");
            if (success) {
                serial1ToSerial2Success++;
            } else {
                serial1ToSerial2Fail++;
            }
        } else {
            Serial.println("\n--- Testing Serial2 -> Serial1 ---");
            bool success = testSerialPair(Serial2, Serial1, "S2->S1");
            if (success) {
                serial2ToSerial1Success++;
            } else {
                serial2ToSerial1Fail++;
            }
        }

        testSerial1ToSerial2 = !testSerial1ToSerial2;

        if ((serial1ToSerial2Success + serial1ToSerial2Fail +
             serial2ToSerial1Success + serial2ToSerial1Fail) % 2 == 0) {
            printStats();
        }
    }
}

Debug Message

When running with b929eb4:

--- Terminal on COM3 | 115200 8-N-1
--- Available filters and text transformations: colorize, debug, default, direct, esp32_exception_decoder, hexlify, log2file, nocontrol, printable, send_on_enter, time
--- More details at https://bit.ly/pio-monitor-filters
--- Quit: Ctrl+C | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H
ets Jun  8 2016 00:22:57

rst:0x1 (POWERON_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:2
load:0x3fff0030,len:4744
load:0x40078000,len:15712
load:0x40080400,len:3152
entry 0x4008059c

========================================
  ESP32 Serial Port Communication Test
  (Diagnostic Version)
========================================

Initializing Serial1...
Serial1 initialized: TX=GPIO12, RX=GPIO15, Baud=115200

=== Serial1 Status ===
  Bytes available to read: 0

Initializing Serial2...
Serial2 initialized: TX=GPIO25, RX=GPIO26, Baud=115200

=== Serial2 Status ===
  Bytes available to read: 0

Connect the following pins together:
  Serial1 TX (GPIO12) -> Serial2 RX (GPIO26)
  Serial1 RX (GPIO15) -> Serial2 TX (GPIO25)

Starting tests in 3 seconds...


--- Testing Serial1 -> Serial2 ---
[S1->S2] Sending: TEST:1:5084
[S1->S2] After flush, checking receiver status...

=== Serial2 (receiver) Status ===
  Bytes available to read: 13
[S1->S2] Read 13 bytes, received: 'TEST:1:5084'
[S1->S2] SUCCESS - Message verified

--- Testing Serial2 -> Serial1 ---
[S2->S1] Sending: TEST:2:10084
[S2->S1] After flush, checking receiver status...

=== Serial1 (receiver) Status ===
  Bytes available to read: 14
[S2->S1] Read 14 bytes, received: 'TEST:2:10084'
[S2->S1] SUCCESS - Message verified

========== Serial Test Statistics ==========
Serial1 -> Serial2: 1 passed, 0 failed (100.0% success)
Serial2 -> Serial1: 1 passed, 0 failed (100.0% success)
============================================

When running with 155a986

--- Terminal on COM3 | 115200 8-N-1
--- Available filters and text transformations: colorize, debug, default, direct, esp32_exception_decoder, hexlify, log2file, nocontrol, printable, send_on_enter, time
--- More details at https://bit.ly/pio-monitor-filters
--- Quit: Ctrl+C | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H
ets Jun  8 2016 00:22:57

rst:0x1 (POWERON_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:2
load:0x3fff0030,len:4744
load:0x40078000,len:15712
load:0x40080400,len:3152
entry 0x4008059c


========================================
  ESP32 Serial Port Communication Test
  (Diagnostic Version)
========================================

Initializing Serial1...
Serial1 initialized: TX=GPIO12, RX=GPIO15, Baud=115200

=== Serial1 Status ===
  Bytes available to read: 0

Initializing Serial2...
Serial2 initialized: TX=GPIO25, RX=GPIO26, Baud=115200

=== Serial2 Status ===
  Bytes available to read: 0

Connect the following pins together:
  Serial1 TX (GPIO12) -> Serial2 RX (GPIO26)
  Serial1 RX (GPIO15) -> Serial2 TX (GPIO25)

Starting tests in 3 seconds...


--- Testing Serial1 -> Serial2 ---
[S1->S2] Sending: TEST:1:5086
[S1->S2] After flush, checking receiver status...

=== Serial2 (receiver) Status ===
  Bytes available to read: 0
[S1->S2] Read 0 bytes, received: ''
[S1->S2] FAILED - Expected: TEST:1:5086, Got: (nothing)

--- Testing Serial2 -> Serial1 ---
[S2->S1] Sending: TEST:2:10085
[S2->S1] After flush, checking receiver status...

=== Serial1 (receiver) Status ===
  Bytes available to read: 0
[S2->S1] Read 0 bytes, received: ''
[S2->S1] FAILED - Expected: TEST:2:10085, Got: (nothing)

========== Serial Test Statistics ==========
Serial1 -> Serial2: 0 passed, 1 failed (0.0% success)
Serial2 -> Serial1: 0 passed, 1 failed (0.0% success)
============================================

Other Steps to Reproduce

I let Claude Code analyze the problem and it came to the following conclusion:

# UART Communication Issue Analysis

## Problem Summary
- **Working Version**: `b929eb467dd88089d51638a7583c177655ec1f83`
- **Broken Version**: `155a9860c337b37ed18b6033957354617d32fd51`
- **Issue**: No data received on either Serial port after switching versions
- **Root Cause**: Commit removed custom `_uartInternalSetPin()` function and replaced it with IDF's `uart_set_pin()`

## The Critical Change

The commit "fix(uart): fixes setPins() when changing RTS and CTS (#12201)" made significant changes to `cores/esp32/esp32-hal-uart.c`:

**Removed (~147 lines):**
- `_uartInternalSetPin()` - Custom Arduino layer pin configuration function
- `_uartTrySetIomuxPin()` - Helper for IOMUX vs GPIO Matrix selection

**Replaced with:**
- Direct calls to IDF's `uart_set_pin()` function

## Key Differences in the Removed Code

The custom `_uartInternalSetPin()` included critical features:

1. **GPIO Sleep Configuration**
   ```c
   #if CONFIG_ESP_SLEEP_GPIO_RESET_WORKAROUND || CONFIG_PM_SLP_DISABLE_GPIO
       gpio_sleep_sel_dis(tx_io_num);  // Prevent TX isolation during sleep
       gpio_sleep_sel_dis(rx_io_num);  // Prevent RX isolation during sleep
   #endif
   ` ``

2. **IOMUX vs GPIO Matrix Routing Logic**
   - Attempted to use IOMUX for direct pad connections (faster)
   - Fell back to GPIO Matrix if IOMUX not available
   - Custom handling for when TX and RX share the same pin

3. **Conditional GPIO Configuration**
   - Different paths for HP UART (Normal) vs LP UART (Low Power)
   - Version-specific handling for ESP-IDF 5.4+ and 5.5+

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

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

[Bascy]

@I-Connect

[Bascy]

Did some more investigating and found the following:

when using the failing commit #155a9860, it will again work if you restore the removed methods (_uartInternalSetPin())and change this line in static bool _uartAttachPins():

if (rxPin >= 0) {
    // forces a clean detaching from a previous peripheral
    if (perimanGetPinBusType(rxPin) != ESP32_BUS_TYPE_INIT) {
      perimanClearPinBus(rxPin);
    }
    // connect RX Pad
	// next line is NOT WORKING
    // bool ret = ESP_OK == uart_set_pin(uart->num, UART_PIN_NO_CHANGE, rxPin, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);		
	// next line is WORKING
    bool ret = ESP_OK == _uartInternalSetPin(uart->num, UART_PIN_NO_CHANGE, rxPin, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);	

[SuGlider]

Thanks @Bascy - I'll investigate it along this week.

[nomakewan]

@SuGlider Can confirm that making the change to esp32-hal-uart.c as Bascy specified restores UART1 and UART2 on pins 43/44 to full working order on my ESP32-S3 on core 3.3.7. The commit they specified does indeed appear to be the culprit for our hardware as well.

I should note however that I did not just make the change to rx but also made the change to tx just to be 100% sure.

EDIT: I tested what would happen if I only restored the old paradigm to rx but not tx and as I thought, the problem returned. So for us the problem was indeed tx and not rx. Considering that the problem was rx for several people, it would appear there is a fundamental problem with the uart_set_pin function.

[SuGlider]

The point is that IDF 5.5.1 had introduced a problem in December/25 that had broken Arduino HardwareSerial.begin(baud, mode, rxPin, txPin).
The previous code of Arduino for _uartInternalSetPin() is just a copy of the IDF 5.4.1 code from uart_set_pin() from October/25.

In the beginning of 2026, IDF was fixed and therefore there was no need for a customized Arduino _uartInternalSetPin() anymore.

As I said, I have already tested the S3 + UART1 using pins 43 and 44 (from default UART0) communicating to an ESP32 Serial1 using just wires.

Anyway, I'll test it using the sketch provided here.

[SuGlider]

@Bascy - I have run exactly the same sketch you are presenting here in this issue with an ESP32 using exactly the same pins as defined in the sketch. It runs perfectly fine using Arduino Core 3.3.7.

ESP32 pin 25 (TX2) connected to pin 15 (RX1)
ESP32 pin 26 (RX2) connected to pin 12 (TX1)

No issue has been found.

Evidences:

Picture of the ESP32 circuit:

UART0 (console) Output using Debug Level messages:

ets Jul 29 2019 12:21:46

rst:0x1 (POWERON_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:4876
ho 0 tail 12 room 4
load:0x40078000,len:16560
load:0x40080400,len:3500
entry 0x400805b4
[    21][D][esp32-hal-cpu.c:316] setCpuFrequencyMhz(): PLL: 480 / 2 = 240 Mhz, APB: 80000000 Hz
=========== Before Setup Start ===========
Chip Info:
------------------------------------------
  Model             : ESP32
  Package           : D0WD-Q5
  Revision          : 3.00
  Cores             : 2
  CPU Frequency     : 240 MHz
  XTAL Frequency    : 40 MHz
  Features Bitfield : 0x00000032
  Embedded Flash    : No
  Embedded PSRAM    : No
  2.4GHz WiFi       : Yes
  Classic BT        : Yes
  BT Low Energy     : Yes
  IEEE 802.15.4     : No
------------------------------------------
INTERNAL Memory Info:
------------------------------------------
  Total Size        :   378016 B ( 369.2 KB)
  Free Bytes        :   335820 B ( 327.9 KB)
  Allocated Bytes   :    34712 B (  33.9 KB)
  Minimum Free Bytes:   329980 B ( 322.2 KB)
  Largest Free Block:   110580 B ( 108.0 KB)
------------------------------------------
Flash Info:
------------------------------------------
  Chip Size         :  8388608 B (8 MB)
  Block Size        :    65536 B (  64.0 KB)
  Sector Size       :     4096 B (   4.0 KB)
  Page Size         :      256 B (   0.2 KB)
  Bus Speed         : 80 MHz
  Flash Frequency   : 80 MHz (source: 80 MHz, divider: 1)
  Bus Mode          : QIO
------------------------------------------
Partitions Info:
------------------------------------------
                nvs : addr: 0x00009000, size:    20.0 KB, type: DATA, subtype: NVS
            otadata : addr: 0x0000E000, size:     8.0 KB, type: DATA, subtype: OTA
               app0 : addr: 0x00010000, size:  1280.0 KB, type:  APP, subtype: OTA_0
               app1 : addr: 0x00150000, size:  1280.0 KB, type:  APP, subtype: OTA_1
             spiffs : addr: 0x00290000, size:  1408.0 KB, type: DATA, subtype: SPIFFS
           coredump : addr: 0x003F0000, size:    64.0 KB, type: DATA, subtype: COREDUMP
------------------------------------------
Software Info:
------------------------------------------
  Compile Date/Time : Feb 21 2026 16:21:39
  Compile Host OS   : windows
  ESP-IDF Version   : v5.5.2-729-g87912cd291
  Arduino Version   : 3.3.7
------------------------------------------
Board Info:
------------------------------------------
  Arduino Board     : ESP32_DEV
  Arduino Variant   : esp32
  Arduino FQBN      : esp32:esp32:esp32:UploadSpeed=921600,CPUFreq=240,FlashFreq=80,FlashMode=qio,FlashSize=4M,PartitionScheme=default,DebugLevel=debug,PSRAM=disabled,LoopCore=1,EventsCore=1,EraseFlash=none,JTAGAdapter=default,ZigbeeMode=default
============ Before Setup End ============


========================================
  ESP32 Serial Port Communication Test
  (Diagnostic Version)
========================================

Initializing Serial1...
Serial1 initialized: TX=GPIO12, RX=GPIO15, Baud=115200

=== Serial1 Status ===
  Bytes available to read: 0

Initializing Serial2...
Serial2 initialized: TX=GPIO25, RX=GPIO26, Baud=115200

=== Serial2 Status ===
  Bytes available to read: 0

Connect the following pins together:
  Serial1 TX (GPIO12) -> Serial2 RX (GPIO26)
  Serial1 RX (GPIO15) -> Serial2 TX (GPIO25)

Starting tests in 3 seconds...

=========== After Setup Start ============
INTERNAL Memory Info:
------------------------------------------

=========== After Setup Start ============
INTERNAL Memory Info:
------------------------------------------
  Total Size        :   378016 B ( 369.2 KB)
  Free Bytes        :   328616 B ( 320.9 KB)
  Allocated Bytes   :    41124 B (  40.2 KB)
  Minimum Free Bytes:   322776 B ( 315.2 KB)
  Largest Free Block:   110580 B ( 108.0 KB)
------------------------------------------
GPIO Info:
------------------------------------------
  GPIO : BUS_TYPE[bus/unit][chan]
  --------------------------------------  
     1 : UART_TX[0]
     3 : UART_RX[0]
    12 : UART_TX[1]
    15 : UART_RX[1]
    25 : UART_TX[2]
    26 : UART_RX[2]
============ After Setup End =============

--- Testing Serial1 -> Serial2 ---
[S1->S2] Sending: TEST:1:5689
[S1->S2] After flush, checking receiver status...

=== Serial2 (receiver) Status ===
  Bytes available to read: 13
[S1->S2] Read 13 bytes, received: 'TEST:1:5689'
[S1->S2] SUCCESS - Message verified

--- Testing Serial2 -> Serial1 ---
[S2->S1] Sending: TEST:2:10689
[S2->S1] After flush, checking receiver status...

=== Serial1 (receiver) Status ===
  Bytes available to read: 14
[S2->S1] Read 14 bytes, received: 'TEST:2:10689'
[S2->S1] SUCCESS - Message verified

========== Serial Test Statistics ==========
Serial1 -> Serial2: 1 passed, 0 failed (100.0% success)
Serial2 -> Serial1: 1 passed, 0 failed (100.0% success)
============================================


--- Testing Serial1 -> Serial2 ---
[S1->S2] Sending: TEST:3:15689
[S1->S2] After flush, checking receiver status...

=== Serial2 (receiver) Status ===
  Bytes available to read: 14
[S1->S2] Read 14 bytes, received: 'TEST:3:15689'
[S1->S2] SUCCESS - Message verified

--- Testing Serial2 -> Serial1 ---
[S2->S1] Sending: TEST:4:20689
[S2->S1] After flush, checking receiver status...

=== Serial1 (receiver) Status ===
  Bytes available to read: 14
[S2->S1] Read 14 bytes, received: 'TEST:4:20689'
[S2->S1] SUCCESS - Message verified

========== Serial Test Statistics ==========
Serial1 -> Serial2: 2 passed, 0 failed (100.0% success)
Serial2 -> Serial1: 2 passed, 0 failed (100.0% success)
============================================


--- Testing Serial1 -> Serial2 ---
[S1->S2] Sending: TEST:5:25689
[S1->S2] After flush, checking receiver status...

=== Serial2 (receiver) Status ===
  Bytes available to read: 14
[S1->S2] Read 14 bytes, received: 'TEST:5:25689'
[S1->S2] SUCCESS - Message verified

--- Testing Serial2 -> Serial1 ---
[S2->S1] Sending: TEST:6:30689
[S2->S1] After flush, checking receiver status...

=== Serial1 (receiver) Status ===
  Bytes available to read: 14
[S2->S1] Read 14 bytes, received: 'TEST:6:30689'
[S2->S1] SUCCESS - Message verified

========== Serial Test Statistics ==========
Serial1 -> Serial2: 3 passed, 0 failed (100.0% success)
Serial2 -> Serial1: 3 passed, 0 failed (100.0% success)
============================================


--- Testing Serial1 -> Serial2 ---
[S1->S2] Sending: TEST:7:35689
[S1->S2] After flush, checking receiver status...

=== Serial2 (receiver) Status ===
  Bytes available to read: 14
[S1->S2] Read 14 bytes, received: 'TEST:7:35689'
[S1->S2] SUCCESS - Message verified

--- Testing Serial2 -> Serial1 ---
[S2->S1] Sending: TEST:8:40689
[S2->S1] After flush, checking receiver status...

=== Serial1 (receiver) Status ===
  Bytes available to read: 14
[S2->S1] Read 14 bytes, received: 'TEST:8:40689'
[S2->S1] SUCCESS - Message verified

========== Serial Test Statistics ==========
Serial1 -> Serial2: 4 passed, 0 failed (100.0% success)
Serial2 -> Serial1: 4 passed, 0 failed (100.0% success)
============================================

[SuGlider]

@Bascy @nomakewan - I'm using the Arduino IDE 2.3..7 with Arduino Core 3.3.7 to build your examples.
It is based on pre compiled IDF 5.5.2 libraries.

This is the board configuration that I have used:

[SuGlider]

Are you using Arduino IDE + Arduino Core 3.3.7 to test it?