USB Serial Driver?

[Dave Squibb]

Hello,
I have compiled the example USB_Serial example program after clicking on Generate Driver. The Driver file is saved to a folder. After programming the PIC18F2550 I connect the USB to the PC and I get the message "One of the USB devices connected to the computer has malfunctioned and windows does not recognise it. In device Manager it says Windows has stopped this device because it has reported problems. (Code 43). Googling Code 43 points to driver problems.
I am not asked to install a driver when I plug the device in. How should I do this? (Windows 7 pro 64 bit)
Thanks,
Dave.

[Benj]

Hi Dave,

It is likely that the problem your having is because the hardware is mis-configured and running at an incorrect speed.

Can you post your program so we can look at your config settings and also can you let us know what crystal frequency your using.

[Dave Squibb]

Hi Benj,
Crystal is 4MHz

USB_Serial.fcfx

(7.3 KiB) Downloaded 217 times

Thanks,

Dave.

[Benj]

Hi Dave,

Thanks that's great.

Please can you try compiling this to the chip and hopefully the USB should then start working correctly.

USB_Serial-2.fcfx

(7.3 KiB) Downloaded 242 times

[Dave Squibb]

Well that works Benj. Why is the clock set to 48MHZ and not 4?
Apart from that is it just the Config that was wrong?
Thanks, Dave.

[Benj]

Hi Dave,

Yep just config and clock speed settings.

Full speed USB runs at 12M bits per second, a PIC has a speed of 1 instruction cycle per 4 clock cycles so to get USB to work the device needs to be running at 48MHz.

The onboard PLL (phase locked loop) built into the oscillator circuit takes your 4MHz input and multiplies up to 48MHz for you to allow the USB to function.