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Information in this article applies to:

  • ULINK USB-JTAG Adapter
  • ULINK2 USB-JTAG Adapter
  • µVision Version 2.39


I use Keil ULINK with the ST uPSD3354DV and cannot read the watchdog registers WDKEY and WDRST.

If I read this registers from the peripheral menu Peripherals - Timer - Watchdog using the µVision Debugger I get the result 0x00.

If I use memory window at the specified address D:0xAE (for WDKEY) and D:0xA6 (for WDRST) I get the same result.

According to the ST specification it should be possible to read this registers. Can you tell me what is wrong? µVision, Keil ULINK, or the ST uPSD?


We have contacted ST with this question, since we could not find any problem in the Keil ULINK or the µVision Debugger.

ST has given us the following answer:

  • On uPSD32xx: WDKEY and WDRST are write only registers. The functionality of the watchdog timer is not as defined in our current documentation.
  • On uPSD33xx and uPSD34xx: WDKEY and WDRST are write only registers. The uPSD33xx data sheet will be corrected to indicate they are WRITE ONLY and not READ/WRITE.


Last Reviewed: Sunday, January 28, 2007

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