tips for debugging interface hardware?

ejorgensen · Post by **ejorgensen** » Tue Sep 16, 2003 9:35 pm

I'd been having some trouble uploading with my simple interface, so i pulled the hood off it to see whether I'd used 1k or 10k resistors. I suspected I'd used 10k, but i used 1k. Scratch that off the list.

So I took a trip down to my friendly neighborhood electronics shop (not the shack), bought the bits and pieces i didn't already have, and built an ultra interface based on the ultraperfboard pdf.

It doesn't work. at all. IR always reports that the test failed because it always reads a 1 - whether or not the cable is plugged into a remote.

I've been going over the circuit, but I haven't spotted any mistakes. So I'm about to go over it again, but i was hoping someone here could give me some tips on what to look for.

So far the closest thing to a problem I've spotted is this. In figure six, it appears that the diagonal lead from pin 6 of u1 is to be cut, but in figure 7 it is present. It doesn't make sense for it not to be present, so i left it in, but maybe I'm just confused.

Since it behaves the same whether or not the remote is connected, I've ruled out the hookup cable as an issue.

I know voltage could be an issue, but supposedly the ultra design is supposed to overcome that sort of thing.

For the record, my simple interface works only with the batteries out of my RCU810, and with or without the batteries in my 15-1918.

Are the parallel port modes important? I'm familiar with homebrew jtag interfaces based on a single 74hc244 where the mode selected in bios mattered.

If voltage is indeed a major issue, what is the best way to determine the voltage supplied by my parallel port? I have a DVM, but what pin do i test and how do i ensure that it is powered when i test it?

Is anyone present who understands the interface well enough that they could point me in the direction of a quick fix? I understand electronics well enough that I've successfully built microcontroller based interfaces from scratch and diagrams, but I'm drawing a blank on this thing.

Thanks

Filebug · Post by **Filebug** » Sun Sep 21, 2003 6:14 pm

The diagonal lead from pin 6 should be present. You'll just have to double check every lead. You may want to view the document showing the Ultra Interface on a printed circuit board for additional reference. The Ultra interface was designed to eliminate voltage problems. Make sure your batteries are installed when you are using the ultra.

http://groups.yahoo.com/group/jp1/files ... 20Designs/

Good Luck!

Tommy Tyler · Post by **Tommy Tyler** » Sun Sep 21, 2003 8:05 pm

I've looked at the file and can't see anywhere that the diagonal lead from pin 6 of U1 has been cut. But I DID see that the diagonal lead from pin 5 to C2 was cut in Figure 6 but not shown cut in the following Figure 7. That lead must be cut, because you can tell from the schematic that C2 is not connected to U1-5. I will fix the file soon. Please let us know if that solves your problem.

Tommy

jwcldwll · Post by **jwcldwll** » Tue Sep 23, 2003 1:40 pm

Im no expert but I had the same problem with a "Store bought" ultra interface so I built the simple one- which also gave the same error messages. I found that running either one on an older computer worked OK- (both computers were running 98SE). The lesson- try another computer- you may get lucky like I did.

Post by **The Robman** » Tue Sep 23, 2003 2:18 pm

Where did you find a store that sells JP1 stuff???
Rob

jamesgammel · Post by **jamesgammel** » Tue Sep 23, 2003 7:57 pm

He didn't. It was obviously a reference to either Slick Rick or Filebug. Both "online stores" with links you provide. I know Rick peddles the ultra, and I'd imagine filebug does as well.

Jim

jwcldwll · Post by **jwcldwll** » Tue Sep 23, 2003 11:23 pm

Jims' right- again! It was a Filebug Ultra that I coudnt make work at first- but it worked fine on a different computer- the same thing happened with my homemade interface so I know it was the computer that wasnt cooperating.

ejorgensen · Post by **ejorgensen** » Wed Sep 24, 2003 12:17 pm

Tommy, thanks for replying, will reexamine pdf and my device.

I did try both devices on another PC. I, er, have several. When i got laid off from my high tech job last year, they told me to take home my severance in hardware, since they sure didn't have any money.

On the other windows machine, I'm guessing there's more voltage on the parallel port. The simple interface is more reliable, and the ultra now always complains 'always returns a 0'.

If my current employment weren't so disruptive of my life, I'd be working on this more often, but, eh.