these days, I am building the pic18f usb device in order to transfer data from the pic to the computer.
I find the pic18f usb device tutorial here: http://www.waitingforfriday.com/index.p ... USB_device

I tried with this. However, it did not work. I build the circuit without external oscillator (I am ordering one which is on its way), the switch.

After I program the PIC and connect to my PC, there is no response. Can you help me figure out what's the problem?

The PIC18F USB interface does not work without an external oscillator. Check out the oscillator and USB sections of the datasheet where the oscillator requirements are stated.

/Simon

hey simon.
today the oscillator came. I tried the full version of the circuit. it still did not work. what can be the problem. I am using the same code as you give. The only difference is: we are using phython chip prog not the pickit3. will that be a problem? To my concern, that is not a problem.
Till now, I can't figure out what's happening.

thanks.

baiyang

I doubt the programmer is the issue, I presume you've used it before to program PICs successfully?

It's more likely to be a hardware issue and there are lots of posts and advice already on the forum about what to check. Confirm your circuit and check the capacitor values are correct. Also make sure your USB cable is correct and that the PIC has 5Vs on all it's power pins.

one of my friends used that one, it works.
the capacitor is correct.
all in all I will try another programmer.
hope it works.

finally the device works. Now I am having some problem on the HID code to control the usb device. The code is a lot. I am wondering the which part should I read through to understand the code theory behind the control method?

Both the firmware and the host application functions are covered in the following article:

http://www.waitingforfriday.com/index.p ... nd_Windows

Please take a look at the firmware and host software explanations there and see if it helps.