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[SOLVED] PIC18f2550 USB problem, unknown device

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hemanteda

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Hi everyone,

I've been trying to build a USB connected board which uses a PIC18F2550 (I-SO) to capture IR (using a TSOP1738). The prototype that I built and tested worked fine (both software and hardware). I then designed the PCB and its not working! The device doesnt get properly detected, I get an "unknown device" or no device at all. Its a simple circuit and I've been going over it again an again failing to find the error. Could someone help me spot the problem? I am able to connect and program using PICkit2 (ICSP connector). The board doesn't work even when remove the MAX232 and TSOP.
 

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Make sure the 4 pins of the USB connector and the case is connected properly. In my experience the Grounding there is important.
Also the VUSB pin usually is connected to a 470nF cap I think. I don't know weather that could be the issue.

I think 90% chance at the USB connector. (Why you left one pin unconnected? Just try by Grounding that also.)
Connect a 1uF capacitor at pin1 to GND and try.(of MCU)

Hope this helps!
 

Hey, tried everything that you suggested... still the same...

I'm able to blink the LED connected to RA5, but no USB
 

stupid mistake on my part, swapped D+ D- :p
 

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