USb Troubles!18F87J50 sort of works?

curt2go · Joined: 21 Nov 2003 Posts: 200

I am using a 18F87J50. I have used a 18F4550 with great success before. I am using the same driver as I was for the 4550. I have changed all the memory locations to suite the 87j50. The USB is sort of working. The problem I am having is that the computer says One of the USB devices attached to this computer has malfunctioned and windows does not recognize it. I am not a USB wiz by any means but the 4550 was working very well in a few applications. Let me know if I am missing something stupid or not.. Thanx in advance...

Guest · Posted: Sat Nov 10, 2007 1:44 pm

Here is some more info.. Itlooks like nothing is getting through right..
I can see data on the lines at around 3.3 volts..
This is what shows up on usbview...

Device Descriptor:
bcdUSB: 0x0000
bDeviceClass: 0x00
bDeviceSubClass: 0x00
bDeviceProtocol: 0x00
bMaxPacketSize0: 0x00 (0)
idVendor: 0x0000
idProduct: 0x0000
bcdDevice: 0x0000
iManufacturer: 0x00
iProduct: 0x00
iSerialNumber: 0x00
bNumConfigurations: 0x00

ConnectionStatus: DeviceFailedEnumeration
Current Config Value: 0x00
Device Bus Speed: Low
Device Address: 0x00
Open Pipes: 0

Guest · Posted: Sat Nov 10, 2007 2:08 pm

Looks like my signal is not very good. Not a consistant bit pattern from what I can tell. Any thoughts on what might help that out?

Guest · Posted: Sat Nov 10, 2007 2:36 pm

Might just be my scope. It is a digital but only goes to 20MHz which I don;t think is fats enough.. So I can not know for sure if the bits are nice really or not..

curt2go · Joined: 21 Nov 2003 Posts: 200

Got it.. You have to set the PLL on. It does not do it automatically like the 4550.. So all you have to do to use the 87j50 is set the registers correctly and make sure you set the PLL on when you start.. Hope that helps some others.. TTY

zypher · Joined: 10 Nov 2007 Posts: 1

FWIW, I ran into the same problem, and to enable the PLL I used the following code I found in the following thread, which worked for me:

http://www.ccsinfo.com/forum/viewtopic.php?t=27276