Answers Database
Virtex Configuration: DONE does not go high, INIT does not go low
Record #6749
Problem Title:
Virtex Configuration: DONE does not go high, INIT does not go low
Problem Description:
Urgency: Standard
General Description:
When attempting to configure a Virtex and the symptoms
are DONE not going high, and INIT not going low, there is a possibility that the Virtex
syncronization word is not being caught, or a bit is being added or lost.
Solution 1:
The Virtex synchronization word is: AA995566
The first two hex values of AA are represented in a binary byte
as: 1010 1010
The Most Significant Bit of each byte must be on D0 of Virtex (for SelectMAP).
In this case that means the left most 1 will be fed on to D0, the
adjacent 0 will then be on D1 etc.
Make sure that you are presenting the data appropriately on the
Virtex data pins.
Solution 2:
If a bit (or byte) is added or lost during configuration (perhaps because of clock glitching or noise)
the rest of the bitstream will be misaligned. Each packet after the false edge will be one clock
off, so the Virtex device will not recognize it properly. Thus, no more data will be loaded,
and no CRC will happen, causing INIT to stay high, and DONE to stay low.
End of Record #6749 - Last Modified: 02/03/00 07:43 |
