PIC USB Programmer

[malc-c]

I came across a guy on e-bay selling ready built GTP-USB programmers. He also offers bare boards and complete kits for £21

http://www.ct-tuning.co.uk

I've purchased a bare PCB as I had 99% of the descrete components (just waiting for the order from RS to arrive with the crystals in) - I received the board and USB socket for £5.00. The quality of the PCB is very good.

I also have the original HEX firmware and winpic800 ver 3.55g when the originator made the files available. Later versions are only supported by the commercial GTP-USB plus programmer.

I'll let you know how it performs

[skimask]

I don't know the exact specifics of why this works, but it does for a lot of things.
One problem I've been coming across when using various USB devices is the fact that a lot of people are plugging them into the 'front ports' of their cases. These USB ports are generally (not always) connected to a USB hub chip on the motherboard and introduces some latency in the communications. The programming software doesn't get a response in time, then fails.
The rear USB ports are almost always connected directly to the motherboard's chipset and are in a direct line with the system.
I've got 3 different MP3 players, a couple of USB type programmers for various chip types, and a few other USB devices. Almost all of them have problems with the front ports when trying to reprogram them. None of them have any problem when doing basic communications (bulk transfers, etc.).

Basically, it boils down to not using a USB hub, even the front ports in most systems are effectively on a hub, whereas the rear ports aren't.

Hope that helps somebody out. It hooked me up...

[mvs_sarma]

Hi all

I understand that Microchips PICkit2 is presently available at very low prices almost around 20 bucks? someone can check it. if so why not picKIT2

[skimask]

Hi all

I understand that Microchips PICkit2 is presently available at very low prices almost around 20 bucks? someone can check it. if so why not picKIT2

Microchip PICKIT2 direct from Microchip on-line is $40USD, but they're out of stock.
Digikey has the same thing at the same price, and they're in stock.

[mvs_sarma]

I don't know the exact specifics of why this works, but it does for a lot of things.
One problem I've been coming across when using various USB devices is the fact that a lot of people are plugging them into the 'front ports' of their cases. These USB ports are generally (not always) connected to a USB hub chip on the motherboard and introduces some latency in the communications. The programming software doesn't get a response in time, then fails.
The rear USB ports are almost always connected directly to the motherboard's chipset and are in a direct line with the system.
I've got 3 different MP3 players, a couple of USB type programmers for various chip types, and a few other USB devices. Almost all of them have problems with the front ports when trying to reprogram them. None of them have any problem when doing basic communications (bulk transfers, etc.).

Basically, it boils down to not using a USB hub, even the front ports in most systems are effectively on a hub, whereas the rear ports aren't.

Hope that helps somebody out. It hooked me up...

Hi,

it is a nice and useful observation. Perhaps we have to see whether the front ports are served by a flat cable and not couing up for speed. how ever we are working at very low speed while programming the PICs or any other devices. it should not matter-- this point is worth analyzing.

Ps: in my pc with chinese cabinet, i find a twisted pair wires connected. but no FT232 chip aroun the pins. thus it may perhaps be travelling longer distance on the mother bd itself.(Intel 915GLVG)

[skimask]

Hi,

it is a nice and useful observation. Perhaps we have to see whether the front ports are served by a flat cable and not couing up for speed. how ever we are working a t very low speed while programming the PICs or any other devices. it should not matter-- this point is worth analyzing.

Yes, we are working at low speeds, nowhere near even the USB 1.1 limit. The problem is that USB works in packets, it 'saves up' data, then spits it out in bulk and waits 'x' amount of time for a response. It's got nothing to do with the cable (well, ok, 3 strands of wire aren't going to work very well ). If you've got a 'hub' in the middle (like most front USB port setups), it's another millisecond or two of waiting for whatever software is running on Windows. That extra millisecond is what causes some Windows program to dump thinking that the device has disconnected...or something...

You're right...it shouldn't matter. But, like I've said, I've got an iPod Shuffle, Mobiblu Cube, RCA Lyra (all mp3 players), a Warp13a running on a USB-serial converter, a cheap Lexmark printer, a 2.5" USB hard drive case, a Thrustmaster HOTAS Cougar joystick/throttle, and a full setup of CHProducts Virtual Flight Yoke, Pedals, Throttle setup...
I've also got 2 different PC's, one is a cheap, low end Soyo motherboard, the other is a high end Asus type. None of the above mentioned items will work 100% of the time on the front ports and none of them will 'flash upgrade' on the front ports at any time; All of then will work 100% of the time and 'flash upgrade' without problem on the rear ports. And, on my Dell 8200 laptop, everything flash upgrades just fine when plugged directly into the laptop. But as soon as I plug in a USB hub of some type, they fail 99% of the time.

I've duplicated this behavior on a half a dozen computers (prebuilt Dell & Gateway types, home builts, top of the line, bottom of the barrel, etc), neighbors, friends, co-workers, etc. (after awhile it just becomes pointless to test a theory, but ya know, why not).

I don't know if it's Windows XP (although I've tried it using WinME, Win2K, and Win98SE w/ USB patch and they do the same thing) or just some obscure USB driver bug that most manufacturers seem to have...

Beats me... I just know that plugging into the rear (direct motherboard connect) ports always works for me when doing something sensitive like flash upgrading something. For regular use, front ports work fine.