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MON251 Target Monitor

MON251 is a full-featured, license-free, royalty-free target monitor designed for the 251 microcontroller family. It may be configured for a wide variety of systems. MON251 communicates with the µVision Debugger using the PC's COM port.

MON251 helps you easily debug your target programs in real-time. You can view program symbols, debug using your source code, watch program variables, examine memory contents, and more!

Hardware Requirements

  • 5 Kbytes CODE Space for MON251
  • 256 bytes of DATA memory
  • Serial port for the PC interface
  • Serial Interrupt

Software Requirements

MON251 can be configured to load your target program at address 0FF0000h or at another address.

Starting Target Programs At Offset 0FF0000h

If your target program loads at offset 0FF0000h, you must reserve space for the serial interrupt vector used by the monitor. The easiest way to do this is with the RESERVE linker command.

L251 mycode.obj RESERVE (23h - 25h)

The linker command line reserves the interrupt vector for the 251's on-chip serial port. If you use the second serial port (only available on some devices) or an external UART, the address range specified for the reserve command will be different.

Starting Target Programs At Non-Zero Offsets

If your target program loads at an offset other than 0000h, you must do several things to compile and link for debugging with the monitor. Refer to the following help file for more information on how to relocate your target program.

MON251 Help File

To help you better understand and utilize the power of MON251, we have create a Windows Help file that contains all the information you need to get started.

Click Here to download the MON251 Help File.

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