espressif/usb_host_msc

uploaded 2 days ago

# USB Host MSC (Mass Storage Class) Driver [](https://components.espressif.com/components/espressif/usb_host_msc) This directory contains an implementation of a USB Mass Storage Class Driver implemented on top of the [USB Host Library](https://docs.espressif.com/projects/esp-idf/en/latest/esp32s2/api-reference/peripherals/usb_host.html). MSC driver allows access to USB flash drivers using the BOT (Bulk-Only Transport) protocol and the Transparent SCSI command set. ## Usage - First, usb host library has to be initialized by calling `usb_host_install` - USB Host Library events have to be handled by invoking `usb_host_lib_handle_events` periodically. In general, an application should spawn a dedicated task handle USB Host Library events. However, in order to save RAM, an already existing task can also be used to call `usb_host_lib_handle_events`. - Mass Storage Class driver is installed by calling `usb_msc_install` function along side with configuration. - Supplied configuration contains user provided callback function invoked whenever MSC device is connected/disconnected and optional parameters for creating background task handling MSC related events. Alternatively, user can call `usb_msc_handle_events` function from already existing task. - After receiving `MSC_DEVICE_CONNECTED` event, user has to install device with `usb_msc_install_device` function, obtaining MSC device handle. - USB descriptors can be printed out with `usb_msc_print_descriptors` and general information about MSC device retrieved with `from usb_msc_get_device_info` function. - Obtained device handle is then used in helper function `usb_msc_vfs_register` mounting USB Disk to Virtual filesystem. - At this point, standard C functions for accessing storage (`fopen`, `fwrite`, `fread`, `mkdir` etc.) can be carried out. - In order to uninstall the whole USB stack, deinitializing counterparts to functions above has to be called in reverse order. ## Performance tuning The following performance tuning options have significant impact on data throughput in USB HighSpeed implementations. For original FullSpeed implementations, the effects are negligible. - By default, Newlib (the implementation of C Standard Library) creates cache for each opened file - The greater the cache, the better performance for the cost of RAM - Size of the cache can be set with C STD library function `setvbuf()` - Sizes over 16kB do not improve the performance any more ## Known issues - Driver only supports flash drives using the BOT (Bulk-Only Transport) protocol and the Transparent SCSI command set ## Examples - For an example, refer to [msc_host_example](https://github.com/espressif/esp-idf/tree/master/examples/peripherals/usb/host/msc) in ESP-IDF

## 1.1.1 - Fix `msc_host_get_device_info` for devices without Serial Number string descriptor https://github.com/espressif/esp-idf/issues/12163 - Fix regression from version 1.1.0 that files could not be opened in PSRAM https://github.com/espressif/idf-extra-components/issues/202 - Fix MSC driver event handling without background task ## 1.1.0 - yanked - Significantly increase performance with Virtual File System by allowing longer transfers - Optimize used heap memory by reusing the Virtual File System buffer - Optimize CPU usage by putting the background MSC task to 'Blocked' state indefinitely when there is nothing to do - Fix MSC commands for devices on interface numbers other than zero - Replace unsafe debug functions for direct access of MSC sectors with private SCSI commands ## 1.0.4 - Claim support for USB composite devices ## 1.0.2 - Increase transfer timeout to 5 seconds to handle slower flash disks ## 1.0.1 - Fix compatibility with IDF v4.4 ## 1.0.0 - Initial version