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Applies to: MCB520 Evaluation Board


Information in this article applies to:


I am using the MCB520 Evaluation Board and debugger with MON51. Whenever I write to Port 1 on the board I lose communication with dScope. What is going on?


Pins P1.2 and P1.3 are used as RXD1 and TXD1 respectively for transmit and receive of Serial Interface 1 on the MCB520. When you write to these pins it destroys the serial communications between the MCB520 board and the debugger.


You can solve this problem by using Serial Interface 0 on the MCB520. This is achieved by rebuilding the MON51 monitor program for Serial Interface 0 (you can rebuild the Monitor by running 'Install' in the MON51 directory). Refer to the section titled 'Install Invocation' in the MON51.HLP file inside the BIN directory.

The original monitor supplied with the MCB520 board is stored on EPROM. This can be erased and the new monitor programmed in. Alternatively the new monitor can be placed into RAM or some other type of memory.

You must plug your serial cable into the connector marked SIO 0 on the MCB520. Ensure that switches SW2-7 (T0) and SW2-8 (R0) are set to the ON position to connect Serial Interface 0 to the microcontroller.


More information can be found in the MCB520 Evaluation Board User's Guide.

Serial Ports 0 and 1 are described on page 21. The microcontroller port pin assignments are described on page 23. The switched T0 and R0 are described on page 61.

Article last edited on: 2005-07-19 10:00:25

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