AT90USBxxx CDC demonstration
Use of this program is subject to Atmel's End User License Agreement.
Please read file LICENSE.TXT for copyright notice.
This embedded application source code illustrates how to implement a CDC application with the AT90USBxxx controller.
By default the sample code is delivered configured for STK525, but this sample application can be configured for both STK525 or AT90USBKey hardware, see TARGET_BOARD define value in config.h file. When using an AT90USBKey only joystich events are send to the USB serial COM port (the full USART <-> USB bridge is not availabla as the AT90USBKey does not provide physical USART interface).
This application will enumerates as a CDC (communication device class) virtual COM port. The application can be used as a USB to serial converter.
This source code is usable with the following compilers:
- IAR Embedded Workbench (5.11A and higher)
- AVRGCC (WinAVR 20080411 and higher).
Support for other compilers may required modifications or attention for:
- compiler.h file
- special registers declaration file
- interrupt subroutines declarations
As illustrated in the figure bellow, the application entry point is located is the main.c file. The main function first performs the initialization of a scheduler module and then runs it in an infinite loop. The scheduler is a simple infinite loop calling all its tasks defined in the conf_scheduler.h file. No real time schedule is performed, when a task ends, the scheduler calls the next task defined in the configuration file (conf_scheduler.h).
The sample dual role application is based on two different tasks:
- The usb_task (usb_task.c associated source file), is the task performing the USB low level enumeration process in device mode.
- The cdc task performs the loop back application between USB and USART interfaces.
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