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# MTP
A USB Media Transfer Protocol device backed by a small in-RAM filesystem that the host can browse, read from and write to.
## What it does
- Presents a single MTP storage preloaded with two read-only objects: `readme.txt` and `tinyusb.png`.
- Supports core MTP operations: get device info, open/close session, get storage IDs and storage info, enumerate object handles, get object info, get object and get partial object, and a device property (device friendly name).
- Lets the host upload one additional object (SendObjectInfo / SendObject) into a 4 KB RAM buffer and delete objects (unless built read-only).
- Handles MTP class control requests: cancel, device reset and get device status.
- LED blink rate indicates bus state (not mounted / mounted / suspended).
## USB Descriptors
| Interface | Class driver |
|-----------|--------------|
| 0 | MTP |
## Configuration
Notable `tusb_config.h` settings:
```c
#define CFG_TUD_MTP 1
#define CFG_TUD_MTP_EP_BUFSIZE 512
#define CFG_TUD_MTP_EP_CONTROL_BUFSIZE 16 // should be enough to hold data in MTP control request
// MTP device info
#define CFG_TUD_MTP_DEVICEINFO_EXTENSIONS "microsoft.com: 1.0; "
#define CFG_TUD_MTP_DEVICEINFO_SUPPORTED_OPERATIONS \
MTP_OP_GET_DEVICE_INFO, \
MTP_OP_OPEN_SESSION, \
MTP_OP_CLOSE_SESSION, \
MTP_OP_GET_STORAGE_IDS, \
MTP_OP_GET_STORAGE_INFO, \
MTP_OP_GET_OBJECT_HANDLES, \
MTP_OP_GET_OBJECT_INFO, \
MTP_OP_GET_OBJECT, \
MTP_OP_GET_PARTIAL_OBJECT, \
MTP_OP_DELETE_OBJECT, \
MTP_OP_SEND_OBJECT_INFO, \
MTP_OP_SEND_OBJECT, \
MTP_OP_RESET_DEVICE, \
MTP_OP_GET_DEVICE_PROP_DESC, \
MTP_OP_GET_DEVICE_PROP_VALUE, \
MTP_OP_SET_DEVICE_PROP_VALUE
#define CFG_TUD_MTP_DEVICEINFO_SUPPORTED_EVENTS \
MTP_EVENT_OBJECT_ADDED
#define CFG_TUD_MTP_DEVICEINFO_SUPPORTED_DEVICE_PROPERTIES \
MTP_DEV_PROP_DEVICE_FRIENDLY_NAME
#define CFG_TUD_MTP_DEVICEINFO_CAPTURE_FORMATS \
MTP_OBJ_FORMAT_UNDEFINED, \
MTP_OBJ_FORMAT_ASSOCIATION, \
MTP_OBJ_FORMAT_TEXT, \
MTP_OBJ_FORMAT_PNG
#define CFG_TUD_MTP_DEVICEINFO_PLAYBACK_FORMATS \
MTP_OBJ_FORMAT_UNDEFINED, \
MTP_OBJ_FORMAT_ASSOCIATION, \
MTP_OBJ_FORMAT_TEXT, \
MTP_OBJ_FORMAT_PNG
```
## Building
CMake:
```bash
mkdir build && cd build
cmake -DBOARD=raspberry_pi_pico ..
cmake --build .
```
Make:
```bash
make BOARD=raspberry_pi_pico all
```
## Try it
The device enumerates as an MTP device and shows up in a file browser (e.g. the Files/Explorer app, or `mtp-detect` / `mtp-files` from libmtp). You should see `readme.txt` and `tinyusb.png`; you can copy a small file onto the device and delete files.
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