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Serial Port

The MCB2103 board connects the on-chip serial UART to the MAX3221 (IC1) which converts the logic signals to RS-232 voltage levels. The UART may be used in bootstrap mode to download other utilities for debugging or downloading flash.

MCB2103 Board Serial Port

In addition to the standard 3-wire interface, the COM0 DB9 connector is wired to allow a board RESET via the DTR pin, and to enable In-System Programming (ISP) via the RTS pin as shown in the figure below.

DB9 Connector Wiring for RESET and ISP


  • The Flash Magic Utility uses the DTR and RTS pins to control Flash downloading. You must install jumpers J1 and J10 to program Flash with this utility.
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