problems with USB programmer

Long story, but in a nutshell:

Browsing e-bay I noticed a guy selling a USB PIC Programmer in kit form. He also stated that he could sell just the pre-programmed PIC and PCB's - so I e-mailed him for further details and it transpires that the programmer is in essence a GTP-USB-lite, but with his own PCB design. As I already had the files, including the HEX and drivers for this project I simply ended up purchasing the bare PCB.

I've since constructed the programmer which, from component identification is based on the attached schematic (only differences are that he uses two LEDs rather than a bi-colour LED, the trannys are BC547's, and the timing caps are 22pf not 15pf as shown). Now comes the strange part.

I hooked up the USB cable, the red LED (RB7) lit up and then went out as the green one (RB6) came on and windows found the new hardware, and on pointing it to the supplied drivers the installation was complete. It's listed in Device manager and there are no conflicts. So far so good !

I then hooked up a 16F84a and connected the ISCP leads via a jumper cable. Launched the version of winpic800 (3.55g) that came with the files and selected the detect device - bingo it came back with "16F84A" - performed a hardware check and it found the programmer and reported all was OK. - Excellent I thought all seems to be working fine.....

I then opened some hex for the target PIC and clicked on the program all button. It squirted the hex to the PIC so fast I hardly saw the progression bar (well its USB2 full speed device) - however it then got to 93% in varification and halted with an error - "No is answer of hardware" (the author is Spanish). From then on any attempt to communicate with the programmer results in the software not being able to open the driver, and I have to un-plug and re-plug in the programmer to reset it all.

So I checked the voltages:

Under normal conditions they are:
Vpp - + 0.01v
Vdd - +5.01v
data - +0.03v
clk - +0.02v

Programing:
Vpp - +13.88v
Vdd - +5.00v
data - +1.57v
clk - +1.4v

The strange thing is that once it's errored and even if you shut down the software, the programmer still retains the programming voltages.

I've tried several pics and they all do the same.

Does anyone have any ideas - or suggestions on things to try ? The fast replies from the vendor to my previous mails seemed to of stopped now..I'm hoping its just because he's gone out for the eveing, and not that he is ignoring my requests for advice !

Sorted - turns out its my UBS ports as it works fine on my sons PC !!!

Looks like a change of motherboard is in order ;)

Quote:

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Originally Posted by malc-c

Sorted - turns out its my UBS ports as it works fine on my sons PC !!!

Looks like a change of motherboard is in order ;)

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Just curious here...
Did you try both front and rear USB ports?
Front mounted USB ports are generally connected to a 'hub' on the motherboard, wheras rear mounted USB ports generally connect directly to the chipset (latency issues, don't ask me why, I just know it works out that way sometimes).

Hi,

Yes I tried all ports (2 headers on the MoBo and 2 sockets on the MoBo) and the same thing happens. I think its probably down to the nForce2 Ultra400 chipset.

It will be a few days befor the new card arrives, but I'll let you know how I get on.

Hi Malc-c,
Curious as to cost of this, and maybe you can give us a link to the seller?
Does it perform now as expected?
regards
JS

Joe, full details can be found at CT Tunings website (http://www.ct-tuning.co.uk)

The cost is £19.99 for the kit

It works great on my son's PC and supports a wide range of common PICs inc the more popular 18F series (like the 18F2550). It also programs chips that require special treatment of the vdd and vpp lines such as the 12F675.

The Kit takes about an hour to build (may be less if you're a fast builder).

All,

I had the same problem with my GTP_USB_Lite only working on some computers. Having read this thread it seemed like the USB chipset was to blame but be careful what other devices you have also.

Using the programmer thrugh USB hubs and extenders can cause issues as it did with me. Connecting directly to the PC's USB ports worked fine. Also make sure you are using WinPic800 ver 3.55 as this (i think) is the last version to support the Lite model. New versions require you to buy the GTP USB Plus.

On another machine i also noticed intermittent problems writing the code. Sometimes it would make 100% and other times it wouldnt. Again this seemed to be down the the USB port and other devices in the way.

All in all i know find my GTP Lite a stable and very fast programmer!

USB Programmer: There is probably no better and few cheaper programmers then the one that Microchip sells inside the PICKIT II development toolbox. It is a small (like 1 by 3 inch by 1/3 inch tall) module with a mini USB connector one end and a 6 pin Berg type socket the other. It can either run stand alone given any hex file (great for PB and PBP), or integrated right into MPLAB if that’s your choice. Does ICSP very fast and cleanly, and can also run your app if all it needs is the 5V USB power at a few mills (probably up to 100 mA but check as I don’t have that spec at hand).

Microchip on the USB: I recently had a run-in trying to get a PIC18F4550 device to work on my USB port. I have some demo code it runs (see the USB section here) nicely. On most computers it works fine, though on my home system it comes up with a USB device error and doesn’t run. When I did go and buy an additional USB card it worked just fine thru that USB port on that same computer, so it is a hardware and not a software issue.