|
Question & Answer
Classification:
Date: Apr 14, 2001
Problem configuring the XS40 from its serial EPROM
Q:
We are using an old version of the XS-40 and a student project is trying to use the serial FPGA EPROM (U7) to automatically configure the FPGA upon power up. I believe that I followed the instructions on the board manual (XS40 Board Manual V1.1). In section 1.9, the procedures is explained and I have tried to follow the procedures without success. I created the bitstream using foundation v2.1. I am using the XSTools through the parallel port.
Are there any suggestions as to why it is not working? I am changing the jumpers to program the EPROM and load from EPROM in accordance with the instructions and I do not get the expected results. The bitstream I used is the same used to program the board through the parallel port and it works without going through the EPROM. The EPROM I am using is the ATMEL 17C256. It has more than ample room to store the required bitstream.
Am I using the wrong bitstream? If so, how to I create the required bitstream?
A:
A shunt is placed on J10 of the XS40 Board to pull the mode pins of the XC4000 FPGA low through some 4.7K resistors. This places the FPGA in the master-serial mode so it can program itself with the contents of the serial EEPROM.
The parallel port data pins attach to mode pins M0 and M2. If these pins are driven high, then they will prevent the FPGA from entering the master-serial mode and it won't configure properly. You can prevent this by opening GXSPORT and explicitly driving D6 and D7 to logic 0, or just disconnect the parallel port cable from the XS40 Board.