jpmschweitzerandClaude Fable 5
cb5826e02b
Root cause (verified against our exact IDF tree, not the community guess): the "258" in "sdio_write_task: Failed to send data: 258" is NOT a timeout (that is 263). 258 = 0x102 = ESP_ERR_INVALID_ARG. On the ESP32-P4, block- mode CMD53 writes require the SOURCE buffer to be 64-byte (cache-line) aligned; the IDF sdmmc driver rejects a misaligned source with INVALID_ARG BEFORE any bus activity. esp_hosts write loop then declares "Unrecoverable host sdio state" and reboots the whole P4. The audio TX payload is not 64-aligned, so streaming mic audio wedged on the very FIRST frame (which is exactly what we saw: listening -> instant Failed to send -> reboot). This also explains why buffer/queue/clock/retry tuning all did nothing: the write never reached the bus. And why our symptom was instant, not after ~100 writes (the community block-mode-desync theory) — it is the first misaligned buffer, every time. Fix: vendored esp_hosted 2.12.11 as an editable local component (overrides the registry copy) and bounce a misaligned TX payload through one aligned DMA scratch buffer in hosted_sdio_write_block (port_esp_hosted_host_sdio.c). TX is serialized by the bus lock so a single static bounce buffer is safe; freed in hosted_sdio_deinit. Host-only change — no C6 reflash. VERIFIED ON HARDWARE (autonomous self-test): 40s of continuous mic-audio upstream streaming — the traffic that previously wedged on the first frame — ran clean, zero timeouts, zero reboots. A guarded SDIO_TX_SELFTEST harness is kept (compiled out) for future SDIO stress testing. Credit: root cause + patch designed via multi-agent investigation; the precise 258=INVALID_ARG decode (correcting the upstream community timeout assumption) came from checking our actual esp_err.h. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
| Supported Hosts | ESP32-P4 | ESP32-S3 |
|---|
SD Card (SDMMC) with ESP-Hosted example
Important
The ESP-IDF
masterbranch has an issue that prevents the SD card and ESP-Hosted from working together when both are using SDMMC. See ESP-IDF Issue 16233 for more information. This code contains a workaround for this issue.
This example demonstrates how to use an SD card on an ESP32-P4 dev board when ESP-Hosted is using SDIO to communicate with the on-board ESP32-C6. It has been modified from the standard ESP-IDF SD Card example.
This example does the following steps:
- Initialise ESP-Hosted and Wi-Fi
- Use an "all-in-one"
esp_vfs_fat_sdmmc_mountfunction to:- initialize SDMMC peripheral,
- probe and initialize an SD card,
- mount FAT filesystem using FATFS library
- register FAT filesystem in VFS, enabling C standard library and POSIX functions to be used.
- Print information about the card, such as name, type, capacity, and maximum supported frequency.
- Perform a Wi-Fi Scan
- Create a file using
fopenand write to it usingfprintf. - Rename the file. Before renaming, check if destination file already exists using
statfunction, and remove it usingunlinkfunction. - Open renamed file for reading, read back the line, and print it to the terminal.
- Perform another Wi-Fi Scan
This example supports SD (SDSC, SDHC, SDXC) cards and eMMC chips.
Hardware
This example requires an ESP32-P4 development board with an SD card slot and an SD card. On this board, the SD card slot is assigned to SDMMC Slot 0, while the on-board ESP32-C6 is connected to the ESP32-P4 on SDMMC Slot 1.
Although it is possible to connect an SD card breakout adapter, keep in mind that connections using breakout cables are often unreliable and have poor signal integrity. You may need to use lower clock frequency when working with SD card breakout adapters.
This example doesn't utilize card detect (CD) and write protect (WP) signals from SD card slot.
Pin assignments for SDMMC Slot 0 on ESP32-P4
On ESP32-P4, SDMMC Slot 0 GPIO pins cannot be customized. The GPIO assigned in the example should not be modified.
The table below lists the default pin assignments.
| ESP32-P4 pin | SD card pin | Notes |
|---|---|---|
| GPIO43 | CLK | 10k pullup |
| GPIO44 | CMD | 10k pullup |
| GPIO39 | D0 | 10k pullup |
| GPIO40 | D1 | not used in 1-line SD mode; 10k pullup in 4-line mode |
| GPIO41 | D2 | not used in 1-line SD mode; 10k pullup in 4-line mode |
| GPIO42 | D3 | not used in 1-line SD mode, but card's D3 pin must have a 10k pullup |
4-line and 1-line SD modes
By default, this example uses 4 line SD mode, utilizing 6 pins: CLK, CMD, D0 - D3. It is possible to use 1-line mode (CLK, CMD, D0) by changing "SD/MMC bus width" in the example configuration menu (see CONFIG_EXAMPLE_SDMMC_BUS_WIDTH_1).
Note that even if card's D3 line is not connected to the ESP chip, it still has to be pulled up, otherwise the card will go into SPI protocol mode.
How to use example
Build and flash
Build the project and flash it to the board, then run monitor tool to view serial output:
idf.py -p PORT flash monitor
(Replace PORT with serial port name.)
(To exit the serial monitor, type Ctrl-].)
See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
Example output
A Wi-Fi Scan is performed before and after accessing the SD Card. This shows that both SDMMC Slots work as expected.
I (2103) transport: Received INIT event from ESP32 peripheral
I (2103) transport: EVENT: 12
I (2113) transport: Identified slave [esp32c6]
I (2113) transport: EVENT: 11
I (2113) transport: capabilities: 0xd
I (2123) transport: Features supported are:
I (2123) transport: * WLAN
I (2123) transport: - HCI over SDIO
I (2133) transport: - BLE only
I (2133) transport: EVENT: 13
I (2133) transport: ESP board type is : 13
I (2143) transport: Base transport is set-up, TRANSPORT_TX_ACTIVE
I (2143) H_API: Transport active
I (2143) transport: Slave chip Id[12]
I (2153) transport: raw_tp_dir[-], flow_ctrl: low[60] high[80]
I (2153) transport: transport_delayed_init
I (2163) esp_cli: Remove any existing deep_sleep cmd in cli
I (2163) esp_cli: Registering command: crash
I (2173) esp_cli: Registering command: reboot
I (2173) esp_cli: Registering command: mem-dump
I (2173) esp_cli: Registering command: task-dump
I (2183) esp_cli: Registering command: cpu-dump
I (2183) esp_cli: Registering command: heap-trace
I (2193) esp_cli: Registering command: sock-dump
I (2193) esp_cli: Registering command: host-power-save
I (2203) hci_stub_drv: Host BT Support: Disabled
I (2203) H_SDIO_DRV: Received INIT event
I (2203) H_SDIO_DRV: Event type: 0x22
I (2213) H_SDIO_DRV: Write thread started
I (2643) example: Initializing SD card
I (2643) example: Using SDMMC peripheral
W (2643) ldo: The voltage value 0 is out of the recommended range [500, 2700]
I (2643) RPC_WRAP: ESP Event: wifi station started
I (2653) RPC_WRAP: ESP Event: wifi station started
I (2743) example: Mounting filesystem
I (2743) sdmmc_periph: sdmmc_host_init: SDMMC host already initialized, skipping init flow
I (2953) example: Filesystem mounted
I (2953) example: Doing Wi-Fi Scan
I (3653) rpc_req: Scan start Req
W (3653) rpc_rsp: Hosted RPC_Resp [0x21a], uid [4], resp code [12298]
I (6183) RPC_WRAP: ESP Event: StaScanDone
I (6203) example: Total APs scanned = 11, actual AP number ap_info holds = 10
Name: SD16G
Type: SDHC
Speed: 40.00 MHz (limit: 40.00 MHz)
Size: 14868MB
CSD: ver=2, sector_size=512, capacity=30449664 read_bl_len=9
SSR: bus_width=4
I (6213) example: Opening file /sdcard/hello.txt
I (6303) example: File written
I (6323) example: Renaming file /sdcard/hello.txt to /sdcard/foo.txt
I (6333) example: Reading file /sdcard/foo.txt
I (6333) example: Read from file: 'Hello SD16G!'
I (6333) example: Opening file /sdcard/nihao.txt
I (6353) example: File written
I (6353) example: Reading file /sdcard/nihao.txt
I (6363) example: Read from file: 'Nihao SD16G!'
I (6363) example: Card unmounted
I (6363) example: Doing another Wi-Fi Scan
I (6363) rpc_req: Scan start Req
I (8863) RPC_WRAP: ESP Event: StaScanDone
I (8883) example: Total APs scanned = 11, actual AP number ap_info holds = 10
I (8883) main_task: Returned from app_main()
Done
Troubleshooting
Card fails to initialize with sdmmc_init_sd_scr: send_scr (1) returned 0x107 error
Check connections between the card and the ESP32. For example, if you have disconnected GPIO2 to work around the flashing issue, connect it back and reset the ESP32 (using a button on the development board, or by pressing Ctrl-T Ctrl-R in IDF Monitor).
Card fails to initialize with sdmmc_check_scr: send_scr returned 0xffffffff error
Connections between the card and the ESP32 are too long for the frequency used. Try using shorter connections, or try reducing the clock speed of SD interface.
Failure to mount filesystem
example: Failed to mount filesystem.
The example will be able to mount only cards formatted using FAT32 filesystem.