Twai Treiber

[MSP-Mystic-Lagoon2025]

Board

Arduino NanoESP32

Device Description

Environment

• Development Kit: Arduino Nano ESP32
• Kit version (for WiKi): Not applicable
• Module or chip used: ESP32-S3-MINI-1-N8
• IDF version (run git describe --tags to find it):
  • Arduino-ESP32 Core: v2.0.18-arduino.5
  • ESP-IDF: v4.4.7-dirty
• Build System: Arduino IDE 2.x
• Compiler version (run xtensa-esp32-elf-gcc --version to find it): xtensa-esp32s3-elf-gcc 2021r2-p5
• Operating System: Windows
• Using an IDE: Arduino IDE / PlatformIO
• Power Supply: USB

---

Problem Description

The TWAI (CAN) driver on ESP32-S3 reports successful message transmission (ESP_OK) but messages are not physically transmitted on the CAN bus. The twai_transmit() function completes in 0 milliseconds, which is physically impossible for actual CAN transmission at 500 kbit/s (should take 5-50ms).

This issue has been tested extensively with:

• Two different Arduino Nano ESP32 boards (both ESP32-S3)
• Multiple SN65HVD230D CAN transceivers
• Different GPIO pin combinations
• Various baudrates (500k, 125k, 25k)
• Both NORMAL and NO_ACK modes
• Multiple TWAI libraries (native API, ESP32-TWAI-CAN, arduino-CAN)

The result is always the same: 0ms transmission time = no physical output.

---

Expected Behavior

When calling twai_transmit() with a valid CAN message:

1. Function should take 5-50ms to complete (depending on baudrate and bus arbitration)
2. CAN message should be physically transmitted on CAN_H/CAN_L differential lines
3. A second ESP32 board (receiver) should receive the message
4. Multiple consecutive transmissions should work reliably

---

Actual Behavior

Observed with NORMAL Mode (2 boards connected):

[0] TX... OK (1ms)     ← First message appears to work
[1] TX... OK (0ms)     ← 0ms = NOT physically sent!
[2] TX... OK (0ms)
[3] TX... OK (0ms)
[4] TX... OK (0ms)
[5] TX... OK (0ms)
[6] TX... ERROR 263 (2000ms)  ← ESP_ERR_TIMEOUT
[7] TX... ERROR 263 (2000ms)

Receiver board: No messages received (0 messages)

Observed with NO_ACK Mode (single board loopback):

[0] OK (32 µs)
[1] OK (7 µs)
[2-15] OK (7-11 µs)    ← Works for ~15 messages
[16] ERROR 259 (3 µs)  ← ESP_ERR_INVALID_STATE
[17+] ERROR 259        ← Continues failing

After error 259:

twai_status_info_t status:
  state = TWAI_STATE_RECOVERING (2)
  tx_error_counter = 128+
  bus_error_count = increasing

---

Steps to Reproduce

Hardware Setup:

Board 1 (Sender):

Arduino Nano ESP32
├── GPIO 3 → SN65HVD230 TX (Pin 1)
├── GPIO 2 → SN65HVD230 RX (Pin 4)
├── GPIO 13 → SN65HVD230 Rs (Pin 8) [set to LOW for high-speed]
├── 3.3V → SN65HVD230 VCC
└── GND → SN65HVD230 GND

Board 2 (Receiver):

Same configuration as Board 1

CAN Bus Connection:

Board 1 CAN_H (Pin 7) ──┬── 120Ω ──┬── Board 2 CAN_H
Board 1 CAN_L (Pin 6) ──┤          ├── Board 2 CAN_L
Board 1 GND ────────────┴──────────┴── Board 2 GND

Cable: 30cm twisted-pair, 4-wire
Termination: 120Ω on both ends (measured ~60Ω total)

Software - Sender Code:

#include "driver/twai.h"

#define CAN_TX 3
#define CAN_RX 2

void setup() {
  Serial.begin(115200);
  delay(2000);
  
  Serial.println("TWAI Sender Test");
  
  // Configure TWAI
  twai_general_config_t g_config = TWAI_GENERAL_CONFIG_DEFAULT(
    (gpio_num_t)CAN_TX, 
    (gpio_num_t)CAN_RX, 
    TWAI_MODE_NORMAL
  );
  
  twai_timing_config_t t_config = TWAI_TIMING_CONFIG_500KBITS();
  twai_filter_config_t f_config = TWAI_FILTER_CONFIG_ACCEPT_ALL();
  
  // Install and start
  if (twai_driver_install(&g_config, &t_config, &f_config) == ESP_OK) {
    Serial.println("Driver installed");
  } else {
    Serial.println("Driver install FAILED");
    while(1);
  }
  
  if (twai_start() == ESP_OK) {
    Serial.println("Driver started\n");
  } else {
    Serial.println("Driver start FAILED");
    while(1);
  }
}

void loop() {
  static uint32_t counter = 0;
  
  // Prepare message
  twai_message_t msg;
  msg.identifier = 0x101;
  msg.data_length_code = 5;
  msg.data[0] = 'H';
  msg.data[1] = 'E';
  msg.data[2] = 'L';
  msg.data[3] = 'L';
  msg.data[4] = 'O';
  msg.extd = 0;
  msg.rtr = 0;
  
  // Measure transmission time
  unsigned long start = millis();
  esp_err_t err = twai_transmit(&msg, pdMS_TO_TICKS(2000));
  unsigned long duration = millis() - start;
  
  // Report
  Serial.printf("[%lu] TX... ", counter);
  if (err == ESP_OK) {
    Serial.printf("OK (%lums)\n", duration);  // Shows 0ms after first message!
  } else {
    Serial.printf("ERROR %d (%lums)\n", err, duration);
  }
  
  counter++;
  delay(2000);
}

Software - Receiver Code:

#include "driver/twai.h"

#define CAN_TX 3
#define CAN_RX 2

void setup() {
  Serial.begin(115200);
  delay(2000);
  
  Serial.println("TWAI Receiver Test");
  
  twai_general_config_t g_config = TWAI_GENERAL_CONFIG_DEFAULT(
    (gpio_num_t)CAN_TX, 
    (gpio_num_t)CAN_RX, 
    TWAI_MODE_NORMAL
  );
  
  twai_timing_config_t t_config = TWAI_TIMING_CONFIG_500KBITS();
  twai_filter_config_t f_config = TWAI_FILTER_CONFIG_ACCEPT_ALL();
  
  twai_driver_install(&g_config, &t_config, &f_config);
  twai_start();
  
  Serial.println("Waiting for messages...\n");
}

void loop() {
  twai_message_t msg;
  
  if (twai_receive(&msg, pdMS_TO_TICKS(100)) == ESP_OK) {
    Serial.println("=== MESSAGE RECEIVED ===");
    Serial.printf("ID: 0x%03X\n", msg.identifier);
    Serial.printf("DLC: %d\n", msg.data_length_code);
    Serial.print("Data: ");
    for (int i = 0; i < msg.data_length_code; i++) {
      Serial.printf("%02X ", msg.data[i]);
    }
    Serial.println("\n========================\n");
  }
}

---

Debug Information

Test 1: Different GPIO Pins Tested

TX Pin	RX Pin	Result
GPIO 3	GPIO 2	0ms (no transmission)
GPIO 0	GPIO 1	0ms (no transmission)
GPIO 5	GPIO 6	0ms (no transmission)

All combinations show the same behavior.

Test 2: Different Baudrates Tested

Baudrate	Result
500 kbit/s	0ms transmission
125 kbit/s	0ms transmission
25 kbit/s	0ms transmission

Baudrate makes no difference.

Test 3: Board Swap Test

Swapped sender and receiver code between boards → Same issue on both boards.

Conclusion: Not a hardware defect of individual board.

Test 4: SN65HVD230 Rs-Pin Configuration

Rs-Pin explicitly set to LOW (high-speed mode):

pinMode(13, OUTPUT);
digitalWrite(13, LOW);  // Rs = LOW = High-Speed

Result: No change, still 0ms transmission.

Test 5: Different Libraries Tested

1. Native TWAI API (driver/twai.h): ❌ 0ms issue
2. ESP32-TWAI-CAN library (handmade0octopus): ❌ Same 0ms issue
3. arduino-CAN library (sandeepmistry): ❌ Doesn't compile for ESP32-S3

All libraries use the same underlying TWAI driver → same bug.

---

Additional Context

Community Reports

Multiple forum posts confirm TWAI issues on ESP32-S3:

• Created library for TWAI-CAN controller that is simple to use #9105
• Stack Overflow reports of S3 TWAI instability
• Community workaround: Use Modbus TCP over WiFi instead of CAN

Comparison with ESP32 Classic

The same code and hardware setup works reliably on ESP32 Classic (non-S3) boards.

This appears to be specific to ESP32-S3 TWAI implementation.

---

Suspected Root Cause

Based on behavior analysis:

1. twai_transmit() returns immediately (0ms) without waiting for physical transmission
2. TX error counter increases after ~15 messages in NO_ACK mode
3. Bus enters RECOVERING state prematurely

Hypothesis: The ESP32-S3 TWAI peripheral may have:

• A bug in the transmission state machine
• Incorrect error handling causing premature bus-off
• GPIO matrix routing issues specific to S3

---

Workaround

Currently using Modbus TCP over WiFi as alternative communication method between devices.

---

Request

1. Can you confirm this is a known issue with ESP32-S3 TWAI?
2. Is there a planned fix in upcoming ESP-IDF or Arduino-ESP32 releases?
3. Are there specific ESP32-S3 hardware revisions where TWAI works correctly?
4. Should users avoid TWAI on ESP32-S3 and use alternatives (SPI CAN controllers, WiFi)?

---

System Logs

Full Serial Output (Sender)

``` TWAI Sender Test Driver installed Driver started

[0] TX... OK (1ms)
[1] TX... OK (0ms)
[2] TX... OK (0ms)
[3] TX... OK (0ms)
[4] TX... OK (0ms)
[5] TX... OK (0ms)
[6] TX... ERROR 263 (2000ms)
[7] TX... ERROR 263 (2000ms)
[8] TX... ERROR 263 (2000ms)

</details>

<details>
<summary>Full Serial Output (Receiver)</summary>

TWAI Receiver Test
Waiting for messages...

(no output - no messages received)

</details>

---

## Thank You

Thank you for maintaining this excellent framework. We appreciate any guidance or fixes you can provide for this issue.

### Hardware Configuration

├──Pin 3 → SN65HVD230 TX (Pin 1)
├── Pin 2 → SN65HVD230 RX (Pin 4)
├── Pin 1 → SN65HVD230 TX (Pin 1)
├── Pin 0 → SN65HVD230 RX (Pin 4)
├── GPIO 23 → SN65HVD230 Rs (Pin 8) [set to LOW for high-speed]


### Version

latest stable Release (if not listed below)

### Type

Task

### IDE Name

Arduino IDE 2.3.6

### Operating System

Windows11

### Flash frequency

gute frage

### PSRAM enabled

yes

### Upload speed

115200

### Description

Twai Treiber problem siehe oben

### Sketch

```cpp
siehe ersten beitrag

Debug Message

siehe ersten beitrag

Other Steps to Reproduce

kann ich nur auf diesem system testen da nur ein windows system und diese arduino nanoESP32 habe

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

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

[me-no-dev]

Unfortunately you are using a very old version of this core (2.0.18 released by Arduino.cc). Please update to a recent version. 3.3.4 is the newest and also supports your board

[MSP-Mystic-Lagoon2025]

Thanks for your reply. Unfortunately, when I select firmware update in the IDE environment, I get a message saying that no supported board is connected. However, the Arduino NanoESP32 is connected to serial port 10. I can retrieve the board information, but I can't perform a firmware update. Do you have instructions for this?

[me-no-dev]

https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html

[MSP-Mystic-Lagoon2025]

Hello and thank you for the instructions. I followed them, and the IDE now shows version 3.3.4 under ESP32, but not for the "ArduinoNanoESP32" board. That one is still at 2.0.18, and there's no higher version available. No entry is displayed under "Firmware Update"; the list is empty because no supported board was found. I'm about to lose my mind.

[lbernstone]

This repository is for the package from Espressif. If you want a newer version from Arduino, you can write a letter to Qualcomm's CEO. At this point, I think you are best off ditching the Arduino package, then wipe your device and treat it like a standard esp32 system.