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AR# 17657

5.2i iMPACT CPLD XC9500/XL/XV - Readback of the usercode signature is different from original value programmed


Keywords: 5.1i, XC9500XL, XC9500XV

Urgency: Low

General Description:
I can select a four-character signature to program into the CPLD during JEDEC generation (Hprep6). After programming the JEDEC into the CPLD, performing a readback of the signature returns a value different from the original signature.

Signature programmed into CPLD is 7777
Signature readback by iMPACT is "ecececec"


The signature is converted to an ASCII code and then programmed as binary into the CPLD. When reading this binary code back out, iMPACT should convert this into ASCII before displaying it to the screen. This final step is not performed, and the binary code is displayed as hex.

In the example above, the ASCII code for the character "7" is 0011 0111 or 37 hex. iMPACT is displaying the returned data in reverse and in hex. EC hex is 1110 1100. Reversing the order yields 0011 0111, which is what was expected.

This issue is fixed in the 6.1i design tools release.
AR# 17657
Date 03/26/2006
Status Archive
Type General Article