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Information in this article applies to:

  • C51 All Versions
  • µVision All Versions


I am using µVision for debugging a project with a Cypress USB device (EZ-USB, FX, FX2). However, the µVision peripheral dialogs contain only standard 8051 peripherals and do not show the memory mapped I/O ports of the Cypress USB devices. Is there a way to display the I/O port values?


Yes, you may use Watch Window of µVision which opens with the menu command View -> Watch & Call Stack Window. Now enter the I/O variables. When you are using the Cypress header file (i.e. EZRegs.h), then you can enter the I/O variables as described in the Cypress documentation (for example OUTB or PINA).

You may also replace the I/O port definitions PORTxCFG, OUTx and PINSx in this register definition file. For example, in EZRegs.h just add a struct that contains all these registers as shown below:

struct IOports  {
  unsigned char PORTACFG;
  unsigned char PORTBCFG;
  unsigned char PORTCCFG;
  unsigned char OUTA;
  unsigned char OUTB;
  unsigned char OUTC;
  unsigned char PINSA;
  unsigned char PINSB;
  unsigned char PINSC;

EXTERN volatile struct IOports xdata IOports _at_ 0x7F93;   // define Cypress I/O ports

Now you can add this single struct to the µVision Watch Window which allows you to review all port values while debugging.


  • µVision Getting Started User's Guide, Chapter 5. Testing Programs

Last Reviewed: Wednesday, August 3, 2005

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