M5 Tab5: WiFi fails to initialize, SDIO errors, MAC is zero at runtime (but correct at bootloader)

[ramya-infinitispark]

Board

M5Stack Tab5 (ESP32-P4)

Device Description

Device: M5Stack Tab5, ESP32-P4 (revision v1.0)

Bootloader identification:
esptool v5.1.0
Serial port COM8:
Connecting...
Connected to ESP32-P4 on COM8:
Chip type: ESP32-P4 (revision v1.0)
Features: Dual Core + LP Core, 400MHz
Crystal frequency: 40MHz
USB mode: USB-Serial/JTAG
MAC: 30:ed:a0:e1:60:3a

Hardware Configuration

• Board: M5Stack Tab5 (ESP32-P4, revision v1.0)
• SD card slot: Empty
• Board powered via USB-C cable to PC
• No external sensors or modules connected
• Using built-in display only
• Programmed/flashed via USB/Serial (esptool v5.1.0, Arduino 3.3.3 core)

Version

latest stable Release (if not listed below)

Type

Bug

IDE Name

Arduino IDE

Operating System

Windows 11

Flash frequency

80MHz

PSRAM enabled

yes

Upload speed

921600

Description

When attempting any WiFi operation (even the basic WiFiServer example), WiFi fails to connect and the following errors appear repeatedly in serial output:

E (3249) sdmmc_common: sdmmc_init_ocr: send_op_cond (1) returned 0x107
E (3250) sdio_wrapper: sdmmc_card_init failed
E (3478) H_SDIO_DRV: card init failed
E (3478) transport: ensure_slave_bus_ready failed
ESP_ERROR_CHECK_WITHOUT_ABORT failed: esp_err_t 0xffffffff (ESP_FAIL) at 0x4003cafe
file:  "./managed_components/espressif__esp_hosted/host/api/src/esp_hosted_api.c" line 156
func: esp_hosted_reconfigure
expression: transport_drv_reconfigure()
E (3496) H_API: ESP-Hosted link not yet up

WiFi never connects, and calls to WiFi.macAddress() always return 00:00:00:00:00:00.

Strikingly, the real MAC is correctly shown by esptool at flash time:

Connecting...
Connected to ESP32-P4 on COM8:
MAC: 30:ed:a0:e1:60:3a

Steps to Reproduce:

1. Use any basic WiFi example (e.g. WebServer or WiFi.macAddress() print) with appropriate credentials.
2. Attempt to connect, observe that SDIO errors occur and WiFi never connects.
3. Serial prints always indicate MAC = 00:00:00:00:00:00 at runtime, but chip MAC is valid in esptool.

Additional Attempts:

• Tried disabling SD in M5Unified (M5.begin(cfg), as well as all possible configs; no effect).
• Sketch does not call SD.begin() or similar anywhere.
• Even the simplest WiFi sketch will not connect.
• Tried both stable and nightly/alpha core releases as of Nov 2025.

Log Excerpt

21:48:37.802 -> Connecting to ... 
21:48:37.802 -> E (3249) sdmmc_common: sdmmc_init_ocr: send_op_cond (1) returned 0x107
...
21:48:38.035 -> E (3478) H_SDIO_DRV: card init failed
...
21:48:38.035 -> E (3496) H_API: ESP-Hosted link not yet up
21:48:38.035 -> WiFi not connected. MAC: 00:00:00:00:00:00

What I expect:

• WiFi should connect as it does on ESP32, ESP32-S3 etc, or at the very least MAC address should be visible at runtime.
• SDIO/hosted link errors should not prevent WiFi stack startup.

Additional Notes:

• This issue does not occur on ESP32 (original) or ESP32-S3.
• I am aware ESP32-P4 support is new. If there is a workaround, documentation, or recommended dev branch/IDF patch, please advise.

Sketch

#include <WiFi.h>

const char* ssid = "my_ssid";
const char* password = "my_password";

void setup() {
    Serial.begin(115200);
    delay(500);

    Serial.println("Serial started!");

    // Set WiFi mode
    WiFi.mode(WIFI_STA);

    // Print MAC address
    String mac = WiFi.macAddress();
    Serial.print("Tab5 MAC: ");
    Serial.println(mac);   // <-- This prints all zeros

    delay(500); // Readability

    // Try to connect to WiFi 
    Serial.print("Connecting to ");
    Serial.println(ssid);

    WiFi.begin(ssid, password);

    int count = 0;
    while (WiFi.status() != WL_CONNECTED && count < 20) {
        delay(500);
        Serial.print(".");
        count++;
    }
    Serial.println();

    if (WiFi.status() == WL_CONNECTED) {
        Serial.println("WiFi connected.");
        Serial.print("IP address: ");
        Serial.println(WiFi.localIP());
    } else {
        Serial.println("WiFi not connected.");
    }
}

void loop() {
  // Nothing here
}

Debug Message

21:48:37.802 -> 
21:48:37.802 -> Connecting to my_ssid
21:48:37.802 -> E (3249) sdmmc_common: sdmmc_init_ocr: send_op_cond (1) returned 0x107
21:48:37.802 -> E (3250) sdio_wrapper: sdmmc_card_init failed
21:48:37.896 -> E (3377) sdmmc_common: sdmmc_init_ocr: send_op_cond (1) returned 0x107
21:48:37.896 -> E (3378) sdio_wrapper: sdmmc_card_init failed
21:48:38.035 -> E (3478) H_SDIO_DRV: card init failed
21:48:38.035 -> E (3478) transport: ensure_slave_bus_ready failed
21:48:38.035 -> ESP_ERROR_CHECK_WITHOUT_ABORT failed: esp_err_t 0xffffffff (ESP_FAIL) at 0x4003cafe
21:48:38.035 -> file: "./managed_components/espressif__esp_hosted/host/api/src/esp_hosted_api.c" line 156
21:48:38.035 -> func: esp_hosted_reconfigure
21:48:38.035 -> expression: transport_drv_reconfigure()
21:48:38.035 -> E (3496) H_API: ESP-Hosted link not yet up
21:48:38.601 -> .................................................................................

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.

[me-no-dev]

@ramya-infinitispark this is probably caused by very old firmware on the C6.

@mantriyogesh what do you think?

[Jason2866]

@ramya-infinitispark Build and Flash the esp-hosted-mcu C6 slave firmware v2.0.17. This version is verified working with latest Arduino

[mantriyogesh]

Hello @me-no-dev, there is thin chance of old slave, only very specific versions (much less probability).

IMO, the slave is blocked or crashed due to something. Or the slave firmware itself doesn't have hosted.

Possibilities (high to low probability):

1. slave experienced crash
2. slave is blocked say watchdog is triggered
3. non hosted slave firmware

We can easily understand the issue if textual logs are both sides are captured..

[ramya-infinitispark]

@ramya-infinitispark Build and Flash the esp-hosted-mcu C6 slave firmware v2.0.17. This version is verified working with latest Arduino

Hello @Jason2866 Thank you for your response. Can you please share the link of the version v2.0.17? I could not find it here. https://github.com/espressif/esp-hosted/tags

[me-no-dev]

@mantriyogesh this is M5-Tab so options to reflash or get logs from the slave are rather limited. I have that device here and will try later to see what will happen

[mantriyogesh]

@me-no-dev noted. @ramya-infinitispark Is it possible to retrieve the slave and host side logs at your side?

@Jason2866 I am actually interested in understanding, why the SDIO card was not available / got unavailable.
@ramya-infinitispark can you please use latest esp-hosted component version (host) version and test?

Worst case, to workaround, if you wish to go to 2.0.17 slave

idf.py create-project-from-example "espressif/esp_hosted=2.0.17:slave"

outside your repo directory. flash using idf.py flash monitor on slave port.

But workaround way would just hide the main problem :(

[ramya-infinitispark]

I tried to burn Tab5 ESP32-C6 Wi-Fi SDIO. Below is what I see:

--chip auto --port COM8 --baud 1500000 --before default_reset write_flash -z --flash_mode dio --flash_freq 80m --flash_size detect 0x000 C:\Users\Ramya-infinitispark\Downloads\M5Burner-v3-beta-win-x64\packages\firmware\b6fa77d8c8c2905c15943b4ff1bf86c8.bin
esptool.py v4.10.0
Serial port COM8
Connecting...

Detecting chip type...
 ESP32-P4
Chip is ESP32-P4 (revision v1.0)
Features: High-Performance MCU
Crystal is 40MHz
USB mode: USB-Serial/JTAG
MAC: 30:ed:a0:e1:60:3a
Uploading stub...
Running stub...
Stub running...
Changing baud rate to 1500000
Changed.
Configuring flash size...
Auto-detected Flash size: 16MB
Unexpected chip id in image. Expected 18 but value was 13. Is this image for a different chip model?

A fatal error occurred: C:\Users\Ramya-infinitispark\Downloads\M5Burner-v3-beta-win-x64\packages\firmware\b6fa77d8c8c2905c15943b4ff1bf86c8.bin is not an ESP32-P4 image. Use --force to flash anyway.

[Jason2866]

@mantriyogesh I dont have the Tab5. The issues not connecting to an AP are common for all boards. In my tests only the v2.0.17 worked well with Arduino and provides a MAC

[Jason2866]

@ramya-infinitispark
You have to use the C6 header pins with an external USB serial adapter to flash the C6! The way you tried is flashing the P4.

Press reset button of the board when flashing the C6. This prevents the P4 disturbing the flash process.

You are flashing at address 0x0 so the firmware has to be a combined one, including bootloader, partition table, otadata and firmware. Is the one you are trying a combined one?

Use baudrate 115200 NOT faster.

[mantriyogesh]

Press reset button of the board when flashing the C6. This prevents the P4 disturbing the flash process.

If you wish to do it via command line,

esptool.py -p <P4_usb_serial_port> --before default_reset --after no_reset run

This will also ask P4 not to disturb while flashing C6.

[mantriyogesh]

@mantriyogesh I dont have the Tab5. The issues not connecting to an AP are common for all boards. In my tests only the v2.0.17 worked well with Arduino and provides a MAC

I see. But here 0x107 is seen. SDIO is dead/non responsive.
older slave would work, but i was curious what this exactly issue is from slave logs.. never mind..

[me-no-dev]

@ramya-infinitispark we have just released v3.3.4. Can you please update, enable core debug to Verbose and try again?

[me-no-dev]

@ramya-infinitispark @mantriyogesh I was able to reproduce the problem. Tab5 comes with hosted slave firmware version 1.4.1 and I do get the following errors:

[  2377][I][esp32-hal-hosted.c:146] hostedInit(): Initializing ESP-Hosted
[  2377][D][esp32-hal-hosted.c:147] hostedInit(): SDIO pins: clk=18, cmd=19, d0=14, d1=15, d2=16, d3=17, rst=54
sdio_mempool_create free:34101988 min-free:34096720 lfb-def:33030132 lfb-8bit:33030132

[  2379][I][esp32-hal-hosted.c:166] hostedInit(): ESP-Hosted initialized!
E (3926) sdmmc_common: sdmmc_init_ocr: send_op_cond (1) returned 0x107
E (3926) sdio_wrapper: sdmmc_card_init failed
E (5818) H_SDIO_DRV: card init failed
E (5818) transport: ensure_slave_bus_ready failed
ESP_ERROR_CHECK_WITHOUT_ABORT failed: esp_err_t 0xffffffff (ESP_FAIL) at 0x4003d630
file: "./managed_components/espressif__esp_hosted/host/api/src/esp_hosted_api.c" line 156
func: esp_hosted_reconfigure
expression: transport_drv_reconfigure()
E (5819) H_API: ESP-Hosted link not yet up

What I also notice is that the slave is not even reset before attempting to connect to it. When using same version host, everything is working correctly. Slave is rebooted and connection works