ATMEL AVR1922 User Manual
http://www.BDTIC.com/ATMEL
AVR1922: Xplain Board Controller Firmware
Features
• USB interface
- Mass-storage to on-board DataFlash® memory
• Atmel® AVR® XMEGATM reset control
1 Introduction
The Xplain board controller, an AT90USB1287, is in charge of some of the lowlevel tasks on boards in the Xplain series. The board controller improves usability
of the main microcontroller, and adds features the main controller lacks, like USB.
Some of the tasks the board controller can handle are moving data to and from the
board over the USB interface, for example mass-storage or USB-to-serial.
Note that not all Xplain boards carry multiple microcontrollers; in these cases the
main microcontroller will provide the board controller features when applicable.
Figure 1-1. Board controller on the Xplain board marked in a red circle
8-bit
Microcontrollers
Application Note
Rev. 8302A-AVR-04/10
2 Xplain Board Controller Hardware Features
http://www.BDTIC.com/ATMEL
This chapter will walk through the features available when having a separate board
controller.
2.1 USB Interface
All Xplain boards features an USB connector. This connector has a dual purpose;
power and USB interfaces. When the USB connector is wired to the board controller,
it can be used for various tasks depending on the firmware.
2.1.1 USB-to-serial Interface
n
The mai
port can then be shared as a CDC/ACM USB class (USB-to-serial) on the USB
interface. Having a USB-to-serial interface can be useful for debugging the main
application running on the board, or for transferring data back and forth to an external
host.
2.1.2 USB Mass-storage Interface
Whe
for the board controller as mass-storage devices on the USB interface. This will
present the on-board flash memory as a block device on the host side, and users are
free to use them as they like. Typically storing data files, images, etc. there, for use
with the main microcontroller.
microcontroller will have one UART wired to the board controller. This serial
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connected to a PC the Xplain board can share any external memories available
2.2 AVR XMEGA Reset Line Control
The board controller has wired an I/O line to the AVR XMEGA reset line. This line can
be used to control the reset state of the main microcontroller.
2.3 AVR XMEGA Program and Debug Interface
To program the main microcontroller, the board controller is wired to the program and
debug interface (PDI) on the AVR XMEGA device. This interface can be used to
program new firmware into the main microcontroller from the board controller.
2
AVR1922
8302A-AVR-04/10
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