[Xc3sprog-users] Missing power for Parallel Cable III

[Joris v. R. <jo...@sr...>]

Hello,

(this has also been reported in the Sourceforge tracker ...)

I get "Missing power for Parallel Cable III" when I run detectchain  
SVN r405 or SVN r440 with a Xilinx Parallel Cable III connected to my  
Digilent Spartan-3 200 board. I am certain that the hardware works  
and is correctly plugged in.

A while ago, SVN r405 used to work fine with a different Digilent  
board (Spartan-3E 1600).

I changed the code of ioparport.cpp to continue after the "Missing  
power" message. That makes the program work just fine.

Strangely, after I run the modified detectchain once, the "Missing  
power" message is absent on subsequent runs. Afterwards, the  
unmodified version of the program also works. Apparently something  
had gotten into a bad state, which got fixed by running the modified  
version of detectchain.

After putting a bitfile into the FPGA with xc3sprog, the "bad state"  
returned. Again, the "Missing power" message. Again one run of  
modified detectchain appears to fix it. The "bad state" does not  
return after unplugging/replugging the parallel cable. The "bad  
state" does return after unplugging/replugging the power of the  
Digilent board.

I added code to print the values of "status" and "data" at the point  
of the error message.
In the "Missing power" condition, status=0xde and data==0.
On subsequent runs, status==0xce and data==0.

All of this is perfectly reproducible so far.

Summary:
* Consistently "Missing power ..." message with Digilent Spartan-3  
200 board.
* One run with a modified version of detectchain makes the problem go  
away.
* Uploading a bitfile with xc3sprog makes the problem reappear.
* Power cycling the FPGA board makes the problem reappear.
* Replugging the parallel cable does not make the problem reappear.

I'm using Linux 2.6.32 on x86_64.

I suggest to turn the error into a warning, since that clearly  
increases the number of boards that can work with xc3sprog.
I'll make a patch, should be trivial.

Greetings, Joris.