Human interface on SAM L21 Xplained Pro:
Introduction
This example shows how to implement a USB host CDC on Atmel MCU with USB module.
Startup
After loading firmware, connect the board (EVKxx,Xplain,...) to a USB device CDC. The example is a bridge between a USART from the main MCU and the USB host CDC interface.
- Led 0 is on when it's host and there is no device connected
- Led 0 blinks when a device is enumerated and USB in idle mode
- The blink is slow (1s) with low speed device
- The blink is normal (0.5s) with full speed device
- The blink is fast (0.25s) with high speed device
- Led 0 is on during data transfer between CDC and UART
- Button SW0 allows to enter the device which support the LPM in LPM suspend mode with remote wakeup feature authorized.
- Only SW0 button can be used to wakeup USB device in LPM suspend mode
About example
The example uses the following module groups:
- Basic modules: Startup, board, clock, interrupt, power management
- USB host stack and CDC modules:
services/usb/
services/usb/uhc/
services/usb/class/cdc/host/
- Specific implementation:
- main.c,
initializes clock
initializes interrupt
manages UI
- specific implementation for each target "./examples/product_board/":
- conf_foo.h configuration of each module
- ui.c implement of user's interface (buttons, leds)