Objective Development Forums

Here is my problem...

I have built my self an AVR USB programmer; it nicely works on older computers with socket A, 939pin 64 bit (nVidia chipset)... But I have a laptop with Intel centrino technology (DELL latitude D510). When I connect the programmer to laptop it says UNKNOWN DEVICE, please reconnect device or replace it, and I get the same error on INTEL CORE DUO computer which is old approximately two months, both computers has an Intel chipset!!

And I have the same problem with Igor Cesko USB IR receiver!

PLEASE HELP

LP Ali

Did you insert a 3.3 V regulator in the processor's supply or take other measures to reduce the voltage levels on D+ and D-?

There are chipsets which accept 5 V levels on USB and others where the input comparator's common mode range is exceeded. These other chipsets don't accept 5 V levels.

If you don't want a regulator, there are two "hacks" to reduce the voltage on D+ and D-: Either you insert two series diodes in the supply instead of the regulator, or you add 3.6 V Zener diodes to limit the voltage at D+ and D-. See for instance the AVR-Doper project.

I hade a similar problem and fixed it by setting the Security and COnfiguration Bits in the chip.