# Getting Started #

## Add TinyUSB to your project

It is relatively simple to incorporate tinyusb to your (existing) project

- Copy or `git submodule` this repo into your project in a subfolder. Let's say it is *your_project/tinyusb*
- Add all the .c in the `tinyusb/src` folder to your project
- Add *your_project/tinyusb/src* to your include path. Also make sure your current include path also contains the configuration file tusb_config.h.
- Make sure all required macros are all defined properly in tusb_config.h (configure file in demo application is sufficient, but you need to add a few more such as CFG_TUSB_MCU, CFG_TUSB_OS since they are passed by IDE/compiler to maintain a unique configure for all boards).
- If you use the device stack, make sure you have created/modified usb descriptors for your own need. Ultimately you need to implement all **tud_descriptor_** callbacks for the stack to work.
- Add tusb_init() call to your reset initialization code.
- Call `tud_int_handler()` (device) and/or `tuh_int_handler()` (host) in your USB IRQ Handler
- Implement all enabled classes's callbacks.
- If you don't use any RTOSes at all, you need to continuously and/or periodically call tud_task()/tuh_task() function. All of the callbacks and functionality are handled and invoked within the call of that task runner.

~~~{.c}
int main(void)
{
  your_init_code();
  tusb_init(); // initialize tinyusb stack

  while(1) // the mainloop
  {
    your_application_code();

    tud_task(); // device task
    tuh_task(); // host task
  }
}
~~~

## Examples

For your convenience, TinyUSB contains a handful of examples for both host and device with/without RTOS to quickly test the functionality as well as demonstrate how API() should be used. Most examples will work on most of [the supported Boards](boards.md). Firstly we need to `git clone` if not already

```
$ git clone https://github.com/hathach/tinyusb tinyusb
$ cd tinyusb
```

TinyUSB examples includes external repos aka submodules to provide low-level MCU peripheral's driver as well as external libraries such as FreeRTOS to compile with. Therefore we will firstly fetch those mcu driver repo by running this command in the top folder repo

```
$ git submodule update --init --recursive
```

It will takes a bit of time due to the number of supported MCUs, luckily we only need to do this once. Or if you only want to test with a specific mcu, you could only fetch its driver submodule.

### Build

To build example, first change directory to an example folder. 

```
$ cd examples/device/cdc_msc
```

Then compile with `make BOARD=[board_name] all`, for example

```
$ make BOARD=feather_nrf52840_express all
```

#### Port Selection

If a board has several ports, one port is chosen by default in the individual board.mk file. Use option `PORT=x` To choose another port. For example to select the HS port of a STM32F746Disco board, use:

```
$ make BOARD=stm32f746disco PORT=1 all
```

#### Port Speed

A MCU can support multiple operational speed. By default, the example build system will use the fastest supported on the board. Use option `SPEED=full/high` e.g To force F723 operate at full instead of default high speed

```
$ make BOARD=stm32f746disco SPEED=full all
```

### Debug

To compile for debugging add `DEBUG=1`, for example

```
$ make BOARD=feather_nrf52840_express DEBUG=1 all
```

#### Log

Should you have an issue running example and/or submitting an bug report. You could enable TinyUSB built-in debug logging with optional `LOG=`. LOG=1 will only print out error message, LOG=2 print more information with on-going events. LOG=3 or higher is not used yet. 

```
$ make BOARD=feather_nrf52840_express LOG=2 all
```

#### Logger

By default log message is printed via on-board UART which is slow and take lots of CPU time comparing to USB speed. If your board support on-board/external debugger, it would be more efficient to use it for logging. There are 2 protocols: 

- `LOGGER=rtt`: use [Segger RTT protocol](https://www.segger.com/products/debug-probes/j-link/technology/about-real-time-transfer/)   
  - Cons: requires jlink as the debugger.
  - Pros: work with most if not all MCUs
  - Software viewer is JLink RTT Viewer/Client/Logger which is bundled with JLink driver package.
- `LOGGER=swo`: Use dedicated SWO pin of ARM Cortex SWD debug header.
  - Cons: only work with ARM Cortex MCUs minus M0
  - Pros: should be compatible with more debugger that support SWO.
  - Software viewer should be provided along with your debugger driver.

```
$ make BOARD=feather_nrf52840_express LOG=2 LOGGER=rtt all
$ make BOARD=feather_nrf52840_express LOG=2 LOGGER=swo all
```

### Flash

`flash` target will use the default on-board debugger (jlink/cmsisdap/stlink/dfu) to flash the binary, please install those support software in advance. Some board use bootloader/DFU via serial which is required to pass to make command

```
$ make BOARD=feather_nrf52840_express flash
$ make SERIAL=/dev/ttyACM0 BOARD=feather_nrf52840_express flash
```

Since jlink can be used with most of the boards, there is also `flash-jlink` target for your convenience.

```
$ make BOARD=feather_nrf52840_express flash-jlink
```

Some board use uf2 bootloader for drag & drop in to mass storage device, uf2 can be generated with `uf2` target

```
$ make BOARD=feather_nrf52840_express all uf2
```
