18F4550 Not Recognised

[mister_e]

higher value may be needed if you experiment some erratic connection failure.

As now, 220nF work great for the really few USB stuff i did as now. you can even place two 220nF (0.22uF) in parrallel or a match of to get the value you want in meantime.

Robert.. OT but KGE will move in the next days/months in the old FLY store near the 30. Will be by far bigger

[Christopher4187]

400nF comes from experience. I know what the datasheet says but with 220nF, I found the 18F4550 had trouble enumerating. It may have been due to my design and for most people 220nF may work fine but I was just giving my experience. I don't think there is any harm in using a higher value cap.

[Demon]

Did you get something like this when you didn't have the proper capacitor value?

First the device is seen, but then it craps out with an error.

Robert

[mister_e]

could be that. probably you should try first to remove all HIDs in the Control panel/System/Hardware/DeviceManager while your unit is connected and then reboot, then retry.

It may also be a Microchip Bootloader problem if you use it. If so, erease the best, reprogram your device without the bootloader, then retry... about now?

If the problem is the Bootloader, be sure you place a pull-up on PORTB.4 and it may solve some problem. When booting, it looks if the PORTB.4 is low to enter the programming mode. So if your pin is floating it may just ruine your life.

I may be out but try this and the capacitor stuff.

Make sure you keep the connection alive every few mSec with the USBSERVICE.

[Demon]

...

Robert.. OT but KGE will move in the next days/months in the old FLY store near the 30. Will be by far bigger

Steve, can you give me more details, I don't know the FLY store. If King George Electronics moves closer to the 30 it's great for me, less distance to travel to buy emergency parts (like a 220nF cap).

Robert

[mister_e]

Robert, Fly is besing the Golf.... between the St-Bruno shopping center and Boulevard Cousineau.. on the voie de service. It will be done in few days week. In meantime, MasterVox at Longeuil.

[Demon]

I'm not using a bootloader, don't know how.

I have a pull-up on B4.

I have USBSERVICE in the loop, my code was generated with HIDMaker FullSpeed.

I don't have the Vusb cap, I have to go buy a couple values.

Robert

[mister_e]

what are the value you have? Any scrapped computer, printer or anything else electronic?

Look for it in there... that's free.. if you don't calculate your time, movement, gas and plah plah plah.

[mister_e]

one thing that just spring to mind... what about your main loop?

Is there some USBIN? if so, remove it and just send few data to know.. what happen now?

[Bruce]

I use 470nF on all my USB boards, and have never had a problem with any. That's the same value used on the MeLabs and Microchip USB development boards.

[Demon]

In ceramics, I have .001uF, .01uF, .1uF, 1uF and some 18pF, 20pF and 22pF. The others I have are 10uF tantalum and a ton of electrolytics.

Robert

[Funky Gibbon]

Hi All,
First thanks to everyone, it seems many heads are better than one and in the end i got it sorted.

Firstly, looking at the 4550 datasheet it seems that all the capacitor does is go to ground so in my wisdom i though nahh, dont need it, i guess i was wrong and should have listened to people

Second, i could never figure out capacitor values but i found some on an old redundant soundcard, the value is marked as 331, this capacitor is now in place and the circuit is working fine, i have tried Microchips mouse demo and it worked ok without the need for drivers on the pc, infact it worked better than expected when i plugged it into the bosses iMac at work and laughed at him trying to figure out what was wrong with his mouse for half an hour.
So anyway 331 works for me on 18F4550 @ 20mhz

Shaun