RGH Programming switch position when using LPT cable

[kaputnik]

Finally I managed to get my new Coolrunner programmed after a few hours of fruitless attempts. The strange thing: it worked only after I got desperate and flipped the programming switch to the NOR position instead of PRG, just to try something I hadn't tried already.

I'm using a DIY LPT programming cable made after GliGli's schematic. There's nothing wrong with the cable, I've programmed a few glitch CPLD:s with it before, and also tested it after a few failed attempts at programming my Coolrunner, by programming a XC9536XL I got left over from an earlier project.

My Coolrunner seems to be the real deal when I compare it to the pictures posted here. For instance, the pin 1 marker dot on the IC is there, the print on the board looks right, and parts of the G in the PRG marking at the programming switch is not there due to the track passthrough hole. Everything so far matches the original picture.

To save myself some datasheet reading and measuring I thought I'd ask here first, just in case someone happens to know: is this as it's intended to be when programming using the GliGli LPT cable? (maybe the switch is only intended to be used when programming with a Nand-X or something like that?) Or is it perhaps a production error? If the latter, what points is the switch supposed to connect in respective setting?

Thanks in advance!

 

[Martin C]

We don't support DIY cables, but can you post a pic as to how you had it all connected (including your 3.3v source for the chip)?

 

[Krafter]

Correct me if I'm wrong here but doesn't the NAND-X power the CR in PRG mode? If that is the case then it makes since that the para cable wouldn't work in that mode. The chip must have 3.3v on it in order to program it.

 

[Martin C]

Correct me if I'm wrong here but doesn't the NAND-X power the CR in PRG mode? If that is the case then it makes since that the para cable wouldn't work in that mode. The chip must have 3.3v on it in order to program it.

Happy to correct you

PRG mode is for programming from either LPT or NAND-x.

 

[kaputnik]

We don't support DIY cables, but can you post a pic as to how you had it all connected (including your 3.3v source for the chip)?

Sorry, I didn't take any pictures of it when I had it lined up, but the JTAG header was definitely connected correctly. Also, I soldered the programmer leads directly to the pinheader, and I got quite some experience of soldering, so bad connection due to cold joints should not have been the issue

Of course I could solder it all up again and snap a few pics, but there wouldn't really be any point to it, as it won't say anything about how it was connected before. You'll just have to believe me when I say it was done right from the beginning

I hooked up the 3.3v solder pad to the 3.3v pin of a 6-pin Molex connector in the PC (outputting 3.31v according to my multimeter, thus voltage inaccuracies shouldn't be the problem) At first I also had the GND line on the Coolrunner connected to a ground pin on the same connector, but removed it to eliminate eventual ground loops. It's not needed as the JTAG gnd pin and the power supply gnd solder pad are electrically connected.

Would it be possible for you to post the Coolrunner PCB layout for me to compare my board against with some continuity tests, or if that's not possible, tell me what each pin on the switch is supposed to be connected to?

 

[Martin C]

"I hooked up the 3.3v solder pad to the 3.3v pin of a 6-pin Molex connector in the PC"

So the fact you have a VCC pin on the programmer side wasn't a giveaway?

THIS is why it wouldn't work in PRG mode! Now your CR is installed (and your 3.3v pad is soldered to the console), switch it to PRG. Yep, the power goes.

THIS is also why we don't support DIY methods as users invariably get it wrong. Luckily for you this time there wasn't any permanent damage.

 

[kaputnik]

"I hooked up the 3.3v solder pad to the 3.3v pin of a 6-pin Molex connector in the PC"

So the fact you have a VCC pin on the programmer side wasn't a giveaway?

THIS is why it wouldn't work in PRG mode! Now your CR is installed (and your 3.3v pad is soldered to the console), switch it to PRG. Yep, the power goes.

THIS is also why we don't support DIY methods as users invariably get it wrong. Luckily for you this time there wasn't any permanent damage.

It's not a dead giveaway, as you not only need the VCCIO on the CPLD powered to program it, but also the VCCINT. I must have done an incorrect assumption when I thought the VCC pad only powered the VCCINTs, and the VCCIO got its power from the parallel port.

But then I got a plausible explanation of what went wrong. Thanks for your answer!

 

[Martin C]

It IS a dead giveaway as that's exactly what the VCC input is there for. Look at gligli's schematics and it shows you such. Failing that, check the Xilinx website for their LPT schematics. Finally, a continuity test between VCC on the Progammer pinout and the 3.3v pad for the Xbox installation would have been the test.

As I said, it's exactly why we don't support LPT DIY cables as people can't follow schematics.

For reference, I have a home-made LPT cable working fine from gligli's schematics with a 6 pin header on it. It takes 3.3v from one of the spare LPT pins and is completely self contained