6.47. USB OTG

6.47.1. Overview

This sample project demonstrates USB OTG functionality, where USB determines whether to act as Host or Device based on the ID signal.
When USB0 port is floating or connected to a Device USB cable (male connector), the USB0 ID signal is high level, and USB0 acts as Device; when USB0 port is connected to a Host USB cable (female connector), the USB0 ID signal is low level, and USB0 acts as Host.

6.47.2. Running the example

6.47.2.1. As Host

Download the program to the development board and run it, use the serial port debugging assistant to view the output log
Connect the Host USB cable (female connector) to the USB0 port, USB0 will switch to Host mode, and the serial port debugging assistant will print the following log:

CherryUSB OTG Sample...
[I/usbotg_core] Switch to HOST mode
[I/USB] EHCI HCIVERSION:0x0100
[I/USB] EHCI HCSPARAMS:0x010011
[I/USB] EHCI HCCPARAMS:0x0006
[I/USB] EHCI ppc:1, n_ports:1, n_cc:0, n_pcc:0
[I/USB] EHCI uses tt for ls/fs device

6.47.2.1.1. Connect Keyboard

When a keyboard is connected to the development board’s USB0 port, the serial port debugging assistant will display the following data:

[D/USB] Port change:0x02
[D/USB] Port 1 change
[D/USB] port 1, status:0x101, change:0x01
[D/USB] Port 1, status:0x101, change:0x00
[D/USB] Port 1, status:0x101, change:0x00
[D/USB] Port 1, status:0x101, change:0x00
[D/USB] Port 1, status:0x101, change:0x00
[D/USB] Port 1, status:0x101, change:0x00
[I/USB] New low-speed device on Hub 1, Port 1 connected
[I/USB] New device found,idVendor:413c,idProduct:2113,bcdDevice:0108
[I/USB] The device has 2 interfaces
[I/USB] Enumeration success, start loading class driver
[I/USB] Loading hid class driver
[I/USB] Ep=81 Attr=03 Mps=8 Interval=24 Mult=00
[I/USB] Register HID Class:/dev/input0
[E/USB] do not support Class:0x03,Subclass:0x00,Protocl:0x00
mount a keyboard

When pressing the keyboard, the data sent by the keyboard will be displayed:

Keyboard Data:0x00 0x00 0x16 0x00 0x00 0x00 0x00 0x00 nbytes:8
Keyboard Data:0x00 0x00 0x16 0x07 0x00 0x00 0x00 0x00 nbytes:8
Keyboard Data:0x00 0x00 0x07 0x00 0x00 0x00 0x00 0x00 nbytes:8
Keyboard Data:0x00 0x00 0x16 0x00 0x00 0x00 0x00 0x00 nbytes:8
Keyboard Data:0x00 0x00 0x16 0x07 0x00 0x00 0x00 0x00 nbytes:8
Keyboard Data:0x00 0x00 0x07 0x00 0x00 0x00 0x00 0x00 nbytes:8
Keyboard Data:0x00 0x00 0x16 0x00 0x00 0x00 0x00 0x00 nbytes:8

6.47.2.1.2. Connect Mouse

When a mouse is connected to the development board’s USB0 port, the serial port debugging assistant will display the following data:

[D/USB] Port change:0x02
[D/USB] Port 1 change
[D/USB] port 1, status:0x100, change:0x01
[D/USB] Port 1, status:0x101, change:0x00
[D/USB] Port 1, status:0x101, change:0x00
[D/USB] Port 1, status:0x101, change:0x00
[D/USB] Port 1, status:0x101, change:0x00
[D/USB] Port 1, status:0x101, change:0x00
[I/USB] New full-speed device on Hub 1, Port 1 connected
[I/USB] New device found,idVendor:046d,idProduct:c542,bcdDevice:0302
[I/USB] The device has 1 interfaces
[I/USB] Enumeration success, start loading class driver
[I/USB] Loading hid class driver
[I/USB] Ep=82 Attr=03 Mps=8 Interval=04 Mult=00
[I/USB] Register HID Class:/dev/input0
mount a mouse

When moving or clicking the mouse, the data sent by the mouse will be displayed:

Mouse Data:0x01 0x00 0xfa 0xff 0x06 0x00 0x00 nbytes:7
Mouse Data:0x01 0x00 0xf8 0xff 0x07 0x00 0x00 nbytes:7
Mouse Data:0x01 0x00 0xf7 0xff 0x07 0x00 0x00 nbytes:7
Mouse Data:0x01 0x00 0xf5 0xff 0x09 0x00 0x00 nbytes:7
Mouse Data:0x01 0x00 0xf4 0xff 0x08 0x00 0x00 nbytes:7

6.47.2.2. As Device

When USB0 port is floating or connected to a Device USB cable (male connector), USB0 will switch to Device mode, and the serial port debugging assistant will print the following log:

CherryUSB OTG Sample...
[I/usbotg_core] Switch to DEVICE mode

Connect the USB cable to the computer, the computer can automatically recognize and install the serial port driver, enumerating a device with one COM port
Open the serial port debugging assistant software, select the enumerated COM port, and click to open the port
Then input characters in the serial port debugging assistant, click send, and the sent characters will be echoed back in the serial port debugging assistant.