PIC USB Programmer

[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)