PIC18F46J50 - USB device not recognised

[pablopaolus]

Hi all,

I'm having problems with PIC18F46J50 and USB, since ir gets stuck at usb_wait_for_enumeration(). Here's the part of my code related to USB operation:

[temtronic]

I suggest you use the examples that CCS supplies in the 'examples' folder before you try your own code. I know that the CDC example does work on a '4550.
Once you've got their program running, then either copy/modify it ,or cut your own, but at least you'll have agret working example.



hth
jay

[ezflyr]

Hi,

Are you sure the PIC is actually running? Are you sure it's running at the intended clock speed?

Every one of my PIC development efforts starts with the ubiquitous 'blinking LED' test. Even for 'cut-n-pasted' working code from other projects, this test tells me definitively that my new PIC project is operating, and operating at the intended speed. I recently had an issue where water-soluble flux residue was preventing the external crystal oscillator from starting, and the PIC was falling back to the internal oscillator. The blinking LED test alerted me that something was amiss before I wasted any more time!

Connect an LED to one of your PIC I/O pins thru a suitable current limiting resistor, and then toggle it repeatedly at a known rate, and see if it operates as expected. One second On, and one second Off is a pretty good test, and is easy to time without special equipment.

John

[Ttelmah]

First thing, you do realise that unlike the 4550, _you_ have to supply Vusb?. USB won't work without this connection.
On the 4550, there is an internal voltage regulator to supply this enabled by Vregen, and only the capacitor is needed. On this chip, you need an external source.

Best Wishes

[pablopaolus]

Thank you all for your answers Let's see:

Ttelmah: Yes, I have supplied Vusb with 3.3V, and bypassed to ground through the 100nF capacitor. Also, I have the Vcap/Vddcore pin connected to a 10uF capacitor to ground (I don't know if this has to do with anything...)

ezflyr: I've also used the 'blinking LED' test, and I've checked that the PIC is running. However, thanks to you I've realised that it's not running at the intended clock speed... I'm lighting on and off every second according to my code, but in practice I can count as far as 3 seconds instead of 1. I don't understand where the error can be, since I'm using a 16Mhz external xtal oscillator and I think my fuses are correct, aren't they? Can this be directly related with USB bad working?

Thank you very much.

PS: Just in case you are wondering, I also have MCLR pin connected to 3.3V through a 10k resistor... I'm saying because this is the typical mistake (I've made it more than once...)

[Ttelmah]

I've been running the 26J50, for a while.
Only differences, 12Mhz clock in, and using a crystal module rather than the crystal.

ECPLL, NOWDT, PLL3, NOXINST, NOCPUDIV, NOFCMEN, NOIESO, NOIOL1WAY, STVREN

I turned off all the 'fall back' stuff when originally I was testing, since this ensures you know that you are running from the external oscillator and not 'falling back' to the internal one. Also since I was doing a lot of peripheral configuration later in my code, 'NOIOL1WAY'.

I'd try:

HSPLL, NOWDT, PLL4, NOXINST, NOCPUDIV, NOFCMEN, NOIESO, NOIOL1WAY, STVREN

Without DEBUG, and 80% matching my working fuses. Then just do the timing test. This does need to be right before trying to get any further, or it'll cause problems later. What compiler version?.

Once this is working, make sure you have:

#define __USB_PIC_PERIF__ 1

Before loading the USB stuff. The code won't automatically detect this chip, so needs to be told to use the PIC USB. Might be the other problem (not sure if it defaults to this peripheral or not).

I'd also start with the standard CDC driver and get this working first.

Best Wishes

[pablopaolus]

Ok, timing test is now properly working. This is what I've done:

1) I've changed my fuses as you have said, but timing test didn't still work.
2) Then I've added:

[Ttelmah]

The compiler version is critical in this (why I asked). The PLL is automatically enabled by the software if you specify a clock rate that needs it with more modern compilers....

Best Wishes

[pablopaolus]

Hello again,

I come back... I've been working on USB CDC connection, which is driving me mad.

Sometimes it works: PIC appears as a virtual COM at Device Manager. I've even been able to communicate with a Labview application I've created. However, it suddenly disappears and disconnects, unable to find the driver. I've made hundreds of trials both in W7 and XP, with the same results. Sometimes PC recognised it... sometimes not... sometimes it seems it's not going to work, then it appears after a minute... then it disconnects...

Any idea, please?
Thank you very much.

[asmboy]