USB

AmebaPro2 provides USB stack features as below:

• Compatible with USB 2.0 specification

• Device-specified API for class and application development

• UVC, CDC and DFU support

UVC

UVC device example

AmebaPro2 ISP can support compressed (H264 / H265 / JPG) and uncompressed (NV16 / NV12) image through UVC (wired transmission), and user can check video on pc with Potplayer, Amcap or RTK-realcam. For uncompressed format, user need to install RTK decoder to get video on computer. User can use following flow to build UVC example. Generate the makefile for the UVC project:

cmake .. -G"Unix Makefiles" -DCMAKE_TOOLCHAIN_FILE=../toolchain.cmake -DEXAMPLE=media_uvcd

Then, use the following command to generate an image:

cmake --build . --target flash

If you need more than one device to be plugged into the same computer, this can be done by changing the UVC name, change the product name below and set it before opening the UVC module.

int set_uvc_string(char *product_name, char *serial_name, unsigned short bcdDevice);
Example: set_uvc_string("UVC_DEV_1", "012345678",0X0010);//The last two items can be left unchanged

USB CDC

CDC device example

AmebaPro2 supports USB cdc device mode that can be used to emulate a serial port providing a virtual COM port UART interface. A CDC loopback example to provided, user can use following flow to build CDC example. Generate the makefile for the CDC project:

cmake .. -G"Unix Makefiles" -DCMAKE_TOOLCHAIN_FILE=../toolchain.cmake -DEXAMPLE=usb_cdc

Then, use the following command to generate an image:

cmake --build . --target flash

CDC Class API

API for Application

API	Description
usbd_cdc_acm_init	Initialize the class with parameters: RX buffer length (rx_buf_len): BULK OUT buffer length TX buffer length (tx_buf_len): BULK IN buffer length Application callback (cb)
usbd_cdc_acm_deinit	De-initialize the class
usbd_cdc_acm_transmit	Transmit BULK IN data to host, the data length shall not be larger than the TX buffer length
usbd_cdc_acm_receive	Prepare to receive BULK OUT data, the data length will be limited to RX buffer length

Application Callback

CDC ACM class provides callbacks for user application, the callbacks are defined:

typedef struct {
    u8(* init)(void);
    u8(* deinit)(void);
    u8(* setup)(u8 cmd, u8 *buf, u16 len, u16 value);
    u8(* receive)(u8 *buf, u32 len);
} usbd_cdc_acm_cb_t;

Description of the callbacks:

API	Description
init	Called at the end of class initialization flow, for application-specific initialization
deinit	Called at the beginning of class de-initialization flow, for application-specific de-initialization
setup	Called at setup phase or data out phase of class-specific control requests, for application-specific setup
receive	Called at data out phase of BULK OUT transfer, for application to handle the received data

USB DFU

AmebaPro2 supports DFU (Device Firmware Upgrade), with DFU user can download firmware to AmebaPro2 over USB, user can use following flow to build DFU example. Generate the makefile for the DFU project:

cmake .. -G"Unix Makefiles" -DCMAKE_TOOLCHAIN_FILE=../toolchain.cmake -DEXAMPLE=usb_dfu_ota

Then, use the following command to generate an image:

cmake --build . --target flash

To support multiple devices running on the same computer, this can be done by changing the dfu serial number.

#ifdef USE_SERIAL_MAC
     unsigned char *mac = LwIP_GetMAC(0);//Get the wifi MAC address
     char buf_serial[24] = {0};
     sprintf(buf_serial, "%02x%02x%02x%02x%02x%02x", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
     printf("buf_serial %s\r\n", buf_serial);
     usbd_dfu_setup_serial_number(buf_serial);
#endif

How to download firmware over USB DFU

Install driver for USB DFU

After the DFU example code is started, and you have USB (CON6) connected to your windows computer, you can see DFU device in Device Manager as below:

If your DFU device is unable to work (driver is not installed), you will see:

In this case, please follow these steps to install the driver:

1. Open “Zadig.exe”

2. Select “USB DFU CLASS”

3. Select “libusb-win32”

4. Click “Install Driver”

Burn DFU firmware to AmebaPro2

1. Copy “ota.bin” from image build folder

2. Run dfu-util tool:

dfu-util -d 1d6b:0202 -a 0 -D ota.bin

3. If DFU is successfully, you will see the result as shown:

USB PoE and Wi-Fi Network Connection Detection

USB PoE or Ethernet should be able to handle the events for physical link connected and disconnected. For the events about physical link, Ethernet may be related to Ethernet cable plugin/unplug, and USB PoE may be related to USB device attach/detach. The following is the flow to switch network between Wi-Fi and USB PoE/Ethernet. The event callbacks set LWIP netif link status and handle IP address for USB Poe/Ethernet interfaces. Finally, the LWIP default gateway is also set to specify the interface used to transmit the packets to external network.