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Information in this article applies to:

  • µVision Version 2.20


Projects that I create and debug on the Cypress EZ-USB FX CY3671 that use the GPIF configuration registers to access the FIFO's can not be viewed using the Keil debugger memory window (region of memory from X:0x7800-0x7B3F). In particular I am trying to watch the AINPF register.


First, in order to read from the AINPF register, you need to make sure that the following steps are used to program the CY3671:

  1. Make sure you are in the slave FIFO mode (IFCONFIG is set to 0x03) .
  2. Make sure that you are not using the memory window to read the variable (AINPF in this case). The registers at address locations 0x7800 and greater are not general purpose RAM. Reading certain registers has some triggering effect on values of other registers. Even though you have set the breakpoint at the following statement AINPF = 0x0a;

If you use the memory window to read values from location 0x7800, the Keil debugger actually reads around 256 address locations (see values displayed for various locations from 0x7800). In essence, reading numerous registers at the same time. In the case of memory locations X:0x7800-0x7B3F, using the memory window is not a good way to assure reliable values of registers in these locations.

Therefore, do not use the memory window to view the AINPIF. Use the "Watch and Call Stack" window and add the specific watch variable in the watch#1 window. This results in reading from one and only one location at a time.


  • Refer to Application Note 162 under Application Note 162 which shows how to program and debug applications with the Cypress EZ-USB Board and the Keil development tools.


Last Reviewed: Saturday, July 9, 2005

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