ASF USB host CDC

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)