ESP32 Forum

Posted: **Wed Aug 23, 2023 9:04 am**

Hello everyone,
I'm relying on the usb_msc component to have an ESP32S3 module read files from an USB drive (FAT32 formatted). I'm working on ESP-IDF v5.1.

For the most part everything works; however today I've stumbled upon a specific USB drive that crashes the internal usb_msc code directly when getting the device information.
The code is from the USB msc example (https://github.com/espressif/esp-idf/tr ... b/host/msc). When connecting the drive, this is the output:

Code: Select all

I (395) example: Waiting for USB stick to be connected
I (845) example: MSC device connected
I (845) example: connection...
*** Device descriptor ***
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0x0
bDeviceSubClass 0x0
bDeviceProtocol 0x0
bMaxPacketSize0 64
idVendor 0x90c
idProduct 0x1000
bcdDevice 1.00
iManufacturer 1
iProduct 2
iSerialNumber 0
bNumConfigurations 1
*** Configuration descriptor ***
bLength 9
bDescriptorType 2
wTotalLength 32
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
bMaxPower 500mA
        *** Interface descriptor ***
        bLength 9
        bDescriptorType 4
        bInterfaceNumber 0
        bAlternateSetting 0
        bNumEndpoints 2
        bInterfaceClass 0x8
        bInterfaceSubClass 0x6
        bInterfaceProtocol 0x50
        iInterface 0
                *** Endpoint descriptor ***
                bLength 7
                bDescriptorType 5
                bEndpointAddress 0x81   EP 1 IN
                bmAttributes 0x2        BULK
                wMaxPacketSize 64
                bInterval 255
                *** Endpoint descriptor ***
                bLength 7
                bDescriptorType 5
                bEndpointAddress 0x2    EP 2 OUT
                bmAttributes 0x2        BULK
                wMaxPacketSize 64
                bInterval 255
Guru Meditation Error: Core  0 panic'ed (LoadProhibited). Exception was unhandled.

Core  0 register dump:
PC      : 0x4200a409  PS      : 0x00060b30  A0      : 0x8200973b  A1      : 0x3fc98d00  
0x4200a409: msc_host_get_device_info at /home/maldus/Source/esp-idf-v5.1/examples/peripherals/usb/host/msc/managed_components/espressif__usb_host_msc/src/msc_host.c:549 (discriminator 4)

A2      : 0x3fc98db8  A3      : 0x3fc98d68  A4      : 0x00000000  A5      : 0x00000000  
A6      : 0x00000002  A7      : 0x00000000  A8      : 0x8200a3fc  A9      : 0x3fc98ce0  
A10     : 0x3fc98db4  A11     : 0x00000000  A12     : 0xffffffff  A13     : 0xfffffff7  
A14     : 0xb33fffff  A15     : 0xb33fffff  SAR     : 0x00000004  EXCCAUSE: 0x0000001c  
EXCVADDR: 0x00000000  LBEG    : 0x400556d5  LEND    : 0x400556e5  LCOUNT  : 0xfffffffe  
0x400556d5: strlen in ROM

0x400556e5: strlen in ROM



Backtrace: 0x4200a406:0x3fc98d00 0x42009738:0x3fc98d50 0x42031063:0x3fc98ec0 0x4037c37d:0x3fc98ef0
0x4200a406: msc_host_get_device_info at /home/maldus/Source/esp-idf-v5.1/examples/peripherals/usb/host/msc/managed_components/espressif__usb_host_msc/src/msc_host.c:547 (discriminator 4)

0x42009738: app_main at /home/maldus/Source/esp-idf-v5.1/examples/peripherals/usb/host/msc/main/msc_example_main.c:206 (discriminator 2)

0x42031063: main_task at /home/maldus/Source/esp-idf-v5.1/components/freertos/app_startup.c:208 (discriminator 13)

0x4037c37d: vPortTaskWrapper at /home/maldus/Source/esp-idf-v5.1/components/freertos/FreeRTOS-Kernel/portable/xtensa/port.c:162





ELF file SHA256: 5ad8d65b7b44cff5

Rebooting...
ESP-ROM:esp32s3-20210327
Build:Mar 27 2021
rst:0x3 (RTC_SW_SYS_RST),boot:0x2b (SPI_FAST_FLASH_BOOT)
Saved PC:0x4037569c
0x4037569c: esp_restart_noos_dig at /home/maldus/Source/esp-idf-v5.1/components/esp_system/port/esp_system_chip.c:57 (discriminator 1)

SPIWP:0xee
mode:DIO, clock div:1
load:0x3fce3818,len:0x16f8
load:0x403c9700,len:0x4
load:0x403c9704,len:0xc00
load:0x403cc700,len:0x2eb0
entry 0x403c9908

In short it crashes with a LoadProhibited Panic in the `msc_host_get_device_info` call; specifically here:

Code: Select all

    len = MIN((dev_info.str_desc_product->bLength - USB_STANDARD_DESC_SIZE) / 2, MSC_STR_DESC_SIZE - 1);
    wcsncpy(info->iProduct, dev_info.str_desc_product->wData, len);
    info->iProduct[len] = 0; // <-----

What could be the issue? Is this specific model of USB drive not supported? If not, can I change anything to fix it?

Posted: **Mon Aug 28, 2023 12:04 pm**

By trying out more closely other USB drives the only discernible difference I can find is in the `bInterval` field, which is 255 (-1, maybe missing data?) for the problematic drive but 1 for every other model I could get my hands on.

Since the library itself crashes I'm at a loss for what else to try. Any advice?

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