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PICList Thread
'[PIC] 18f USB enumerate problem'
2005\11\14@135258 by Paul van der Linden

picon face
Hi,

I've a problem with my board, I've created a board like this:
pic18fusb.online.fr/wiki/uploads/Minimal-for-USB-Bootload.gif
with the only difference I've added an ICD port for programming en
debugging, and the PIC is changed to an 18F2550.

I try to get the Microchip bootloader firmware to run, like described on
this page:
pic18fusb.online.fr/wiki/wikka.php?wakka=UsbBootload
The problem is that I get an error from windows: "USB Device Not
Recognized", and when I check for VID and PID in Device Manager it says
VID_0000&PID_0000.

I think I've configured the configuration bytes wrong like the person on
the Microchip forum: http://forum.microchip.com/tm.asp?m=125094, but I
dont get it working. I've tried several possibilities, but whit no
success. I think this are the configuration bytes which cause the error,
but I don't know which is wrong:

Full-Speed USB Clock Source Selection: Clock src from 96MHz PLL/2
CPU System Clock Postscaler: [OSC1/0SC2 Src: /1][96MHz PLL Src: /2]
96MHz PLL Prescaler: Divide by S (20MHz input]
Oscillator: HS: HS+PLL, USB-HS
USB Voltage Regulator: Enabled

Can anyone help me with these configuration bytes, or suggest it's
something else which causes this error?

Paul

2005\11\14@144355 by Martin Malư

picon face
Hi,

I had the same problem - "Device not recognized". Last week I found
the reason: My capacitor between pin 18 and ground was only 100nF.
Replacing it with cap 470nF everything has started to work.

(I have built the PICkit2 -
www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en023805
, http://ww1.microchip.com/downloads/en/DeviceDoc/PICkit2%20User%20Guide%2051553a.pdf)

Martin

2005\11\14@151527 by Paul van der Linden

picon face
Martin Malý wrote:

>Hi,
>
>I had the same problem - "Device not recognized". Last week I found
>the reason: My capacitor between pin 18 and ground was only 100nF.
>Replacing it with cap 470nF everything has started to work.
>
>(I have built the PICkit2 -
>www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en023805
>, http://ww1.microchip.com/downloads/en/DeviceDoc/PICkit2%20User%20Guide%2051553a.pdf)
>
>Martin
>
>  
>
No, I've bought a 470nF for it. When I check it, I don't know for sure, the describtion says:
u47
100
u47

I don't know for sure, but I said to the man at the store: 470 nF, so it should be the right one.

2005\11\14@155700 by Mike Young

picon face
----- Original Message ----- From: "Martin Malý" <spam_OUTmartin.malyTakeThisOuTspamgmail.com>
> (I have built the PICkit2 -

Why would you do that? $50 seems reasonably low for the package.

(I'm a late-comer; the PICkit2 was my first and only programmer. I'm also new to the list; apologies if the reasoning is abundantly clear in previous context. I didn't find a message archive for the piclist.)

2005\11\14@162730 by Martin Malư

picon face
Not for save $50, just for get more experience with "PIC and USB".
PICkit2 is well documented, simply enough to "homemade" and firmware
w/source code is available, so most  errors are in your HW, not in SW.
:)

MM



> From: "Martin Malý" <.....martin.malyKILLspamspam@spam@gmail.com>
> > (I have built the PICkit2 -
>
> Why would you do that? $50 seems reasonably low for the package.
>
> (I'm a late-comer; the PICkit2 was my first and only programmer. I'm also
> new to the list; apologies if the reasoning is abundantly clear in previous
> context. I didn't find a message archive for the piclist.)

2005\11\14@163439 by Martin Malư

picon face
Did you check pin 14 with oscilloscope? Oscillator is running?

So here are my fuses configuration:

PLLDIV: Div by 5 (20MHz XT)
CPUDIV: No divide
USBPLL: 96MHz PLL/2
OSC: HS w. PLL/HS for USB
FCMEM 0
IESO 0
PWRTEN enabled
BOREN disabled
VREGEN enebaled
MCLRE: I/O
LVP disabled (!)
ICport disabled
STVREN enabled

(For 18F2550, it may be the same for 18F4550)

MM

2005/11/14, Paul van der Linden <pvdl1984spamKILLspamxs4all.nl>:
{Quote hidden}

>

2005\11\14@193153 by Stephen D. Barnes

picon face
Paul van der Linden wrote:

{Quote hidden}

The capacitor you describe above is a 47 microfarad 100 volt capacitor. A 470 nF cap is often labeled .47 uF (note the decimal point before the 47). You have the the wrong value capacitor if 470nF is indeed the correct value.

-- Regards,
Stephen D. Barnes

2005\11\14@200213 by Bob Barr

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face
On Mon, 14 Nov 2005 19:33:12 -0500, "Stephen D. Barnes" wrote:

<snip>
>>
>The capacitor you describe above is a 47 microfarad 100 volt capacitor.
>A 470 nF cap is often labeled .47 uF (note the decimal point before the
>47). You have the the wrong value capacitor if 470nF is indeed the
>correct value.
>

According to the datasheet for the USB chips, the capacitor between
the regulator output and ground should be 200 nF (0.22 uF) +/- 20%.

That value may be a change from the original design spec because the
USB development board has/had a 470 nF cap installed.


Regards, Bob


2005\11\15@020907 by Chen Xiao Fan

face
flavicon
face
The following is for PICkit 2 bootloader (20Meg OSC, full speed,
18F2550).

/** CONFIGURATION BITS For PICKit 2 Bootloader **************/

#pragma config PLLDIV = 5, CPUDIV = OSC1_PLL2, USBDIV = 2
// CONFIG1L
#pragma config FOSC = HSPLL_HS, FCMEM = OFF, IESO = OFF
// CONFIG1H
#pragma config PWRT = ON, BOR = OFF, BORV = 21, VREGEN = ON
// CONFIG2L
#pragma config WDT = OFF, WDTPS = 32768
// CONFIG2H
#pragma config MCLRE = OFF, LPT1OSC = OFF, PBADEN = OFF, CCP2MX = ON
// CONFIG3H
#pragma config STVREN = ON, LVP = OFF, ICPRT = OFF, XINST = OFF, DEBUG =
OFF// CONFIG4L
#pragma config CP0 = OFF, CP1 = OFF, CP2 = OFF, CP3 = OFF
// CONFIG5L
#pragma config CPB = OFF, CPD = OFF
// CONFIG5H
#pragma config WRT0 = ON, WRT1 = OFF, WRT2 = OFF, WRT3 = OFF
// CONFIG6L
#pragma config WRTB = ON, WRTC = OFF, WRTD = OFF
// CONFIG6H
#pragma config EBTR0 = OFF, EBTR1 = OFF, EBTR2 = OFF, EBTR3 = OFF
// CONFIG7L
#pragma config EBTRB = OFF
// CONFIG7H

Regards,
Xiaofan

2005\11\15@020911 by Chen Xiao Fan

face
flavicon
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The following is for PICkit 2 bootloader (20Meg OSC, full speed,
18F2550).

/** CONFIGURATION BITS For PICKit 2 Bootloader **************/

#pragma config PLLDIV = 5, CPUDIV = OSC1_PLL2, USBDIV = 2
// CONFIG1L
#pragma config FOSC = HSPLL_HS, FCMEM = OFF, IESO = OFF
// CONFIG1H
#pragma config PWRT = ON, BOR = OFF, BORV = 21, VREGEN = ON
// CONFIG2L
#pragma config WDT = OFF, WDTPS = 32768
// CONFIG2H
#pragma config MCLRE = OFF, LPT1OSC = OFF, PBADEN = OFF, CCP2MX = ON
// CONFIG3H
#pragma config STVREN = ON, LVP = OFF, ICPRT = OFF, XINST = OFF, DEBUG =
OFF// CONFIG4L
#pragma config CP0 = OFF, CP1 = OFF, CP2 = OFF, CP3 = OFF
// CONFIG5L
#pragma config CPB = OFF, CPD = OFF
// CONFIG5H
#pragma config WRT0 = ON, WRT1 = OFF, WRT2 = OFF, WRT3 = OFF
// CONFIG6L
#pragma config WRTB = ON, WRTC = OFF, WRTD = OFF
// CONFIG6H
#pragma config EBTR0 = OFF, EBTR1 = OFF, EBTR2 = OFF, EBTR3 = OFF
// CONFIG7L
#pragma config EBTRB = OFF
// CONFIG7H

Regards,
Xiaofan

2005\11\15@020917 by Chen Xiao Fan

face
flavicon
face

>Not for save $50, just for get more experience with "PIC and USB".
>PICkit2 is well documented, simply enough to "homemade" and firmware
>w/source code is available, so most  errors are in your HW, not in SW.
>:)
>
>MM

I have not heard many people who builds his own PICkit 2 yet.
Just curious how long you spend to procure all the components
and assemble it? Do you make your own PCB?

I think it is relatively more complicated than Wisp628 and
GTP-Usb Lite to build by your own. That is why I choose to
buy a PICkit 2 (the programmer part is only US$35 but the
shipment will not be cheap). The ready-made PICkit 2 is cute
though with a small casing. However a homemade PICkit 2
will be easier to hack and extend the functionality. ;-)

Regards,
Xiaofan

2005\11\15@034544 by Jan-Erik Soderholm

face picon face
Stephen D. Barnes wrote :

> Paul van der Linden wrote:
>
> > No, I've bought a 470nF for it. When I check it,
> > I don't  know for sure, the describtion says:
> > u47
> > 100
> > u47
> >


> The capacitor you describe above is a 47 microfarad 100 volt
> capacitor.

Sure ?

I'd expect a "u47" to be 0.47 uF
And "4u7" to be 4.7 uF and "47u" to be 47 uF.

Anyway, it's a big difference in the "looks" of
an 470 nF and an 47 uF cap, an 47 uF is probably
an round electrolytic cap.

> A 470 nF cap is often labeled .47 uF
> (note the decimal point before the  47).

An "u" (or "n" or "K" or any other prefix) is
often used as an decimal point, as in 4K7 for an
4.7 Kohm resistor.

Jan-Erik.



2005\11\15@050938 by Martin Malư

picon face
One thing must be said before: I needn't any "programmer", I have a
good one... I was just looking for some well-documented and simply
enough USB device with PIC18F2550 to get experience.

My "PICkit2" is on my own single-side PCB contains one 20MHz crystal,
one PIC18F2550 (in DIL), four capacitors, USB B connector, ICSP pins
and 16-pins header to experiment with. So I have extendable USB device
with as-simple-as-it-can-be PCB (good for HW debugging), with free I/O
pins, with full Microchip's FW source code... Any better idea to start
playing with USB? :)

I wrote "PICkit2", because it has PICKit2 bootloader, its USB section
is "PICkit2-based" and the first test was with PICkit2 original FW (is
very important for debugging to know that all possible errors are in
HW, not in SW).

In fact - I¨ve only "PICkit2 fraction", so I have to apologize you for
mystification. :)

Regards,
MM


2005/11/15, Chen Xiao Fan <.....xiaofanKILLspamspam.....sg.pepperl-fuchs.com>:
{Quote hidden}

> Xiaofan

2005\11\15@051158 by Martin Malư

picon face
470nF with small ceramic body can be labelled as "474", too. (It means
"47" and "4 zeros" pico - 470000 pF = 470nF)

MM



2005/11/15, Jan-Erik Soderholm <EraseMEjan-erik.soderholmspam_OUTspamTakeThisOuTtelia.com>:
{Quote hidden}

> -

2005\11\15@082246 by olin piclist

face picon face
Stephen D. Barnes wrote:
>> No, I've bought a 470nF for it. When I check it, I don't know for sure,
>> the describtion says:
>> u47
>> 100
>> u47
>
> The capacitor you describe above is a 47 microfarad 100 volt capacitor.

I don't think so with the "u" preceeding the number.  In any case, the
difference between 470nF and 47uF at 100V should be very obvious just by
looking at the case.  If it's a small ceramic as I think and not a
electrolytic then it's definitely not 47uF.  Perhaps the OP can supply a
picture?


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2005\11\15@082938 by olin piclist

face picon face
Bob Barr wrote:
> According to the datasheet for the USB chips, the capacitor between
> the regulator output and ground should be 200 nF (0.22 uF) +/- 20%.

This is in the writeup in the USB peripheral chapter.  The specification in
the electrical characteristics section contradicts this.  The minimum
capacitance is higher than 220nF-20% but the maximum is left open.  I asked
Microchip for a clarification on this a couple of weeks ago.  The
preliminary answer I heard is that 220nF+20% is not an upper limit as the
writeup implies, and that more than 220nF is in fact a good idea.  Their own
board uses 470nF if I remember correctly.  I asked if 1uF ceramic would be
OK, and so far they've said it probably is, but I haven't gotten a
definative answer yet.


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2005\11\15@085753 by Paul van der Linden

picon face
Thank you all for the help, the capacitor is right.
What I didn't see, that the value of "Full-Speed USB Clock Source
Selection", was changed on an weird way(I don't know how), it wasn't the
value "Clock src from 96MHz PLL/2", but "Clock src from OSC1/0SC2". Now
it's working excellent. Sorry for this mistake.

Another question: has anyone have some tips for beginning pic-USB
programming in C?

2005\11\15@091904 by Jan-Erik Soderholm

face picon face
Paul van der Linden wrote :

> Another question: has anyone have some tips
> for beginning pic-USB programming in C?

The "mouse" example in the USB framework from
Microchip maybe ? It's a complet app, and should be
able to be modified to other HID's or other uses.

Jan-Erik.


>



2005\11\15@092724 by Martin Malư

picon face
> Another question: has anyone have some tips for beginning pic-USB
> programming in C?

Try this:

www.microchipc.com/sourcecode/#pic18f4550usb
http://www.create.ucsb.edu/~dano/CUI/#Sec3

MM

2005\11\15@174904 by Bob Barr

flavicon
face
On Tue, 15 Nov 2005 08:31:11 -0500, Olin Lathrop wrote:

>Bob Barr wrote:
>> According to the datasheet for the USB chips, the capacitor between
>> the regulator output and ground should be 200 nF (0.22 uF) +/- 20%.
>
>This is in the writeup in the USB peripheral chapter.  The specification in
>the electrical characteristics section contradicts this.  The minimum
>capacitance is higher than 220nF-20% but the maximum is left open.  I asked
>Microchip for a clarification on this a couple of weeks ago.  The
>preliminary answer I heard is that 220nF+20% is not an upper limit as the
>writeup implies, and that more than 220nF is in fact a good idea.  Their own
>board uses 470nF if I remember correctly.  I asked if 1uF ceramic would be
>OK, and so far they've said it probably is, but I haven't gotten a
>definative answer yet.
>

Thanks, Olin. You're right, I was going by the write-up and neglected
to confirm that value in the specs section. It's clearly listed as 220
nF minimum as parameter D324.


Regards, Bob

2005\11\15@185600 by Stephen D. Barnes

picon face
Jan-Erik Soderholm wrote:

{Quote hidden}

--

Regards,
Stephen D. Barnes

2005\11\15@190935 by Paul van der Linden

picon face
Bob Barr wrote:

{Quote hidden}

I've searched for that kind of information in different documents, but
still didn't found that. Where can I find that kind of values? I've
already searched in the datasheet of the chips, and the reference manual.

2005\11\15@235426 by Bob Barr

flavicon
face
On Wed, 16 Nov 2005 01:08:46 +0100, Paul van der Linden wrote:


>>Thanks, Olin. You're right, I was going by the write-up and neglected
>>to confirm that value in the specs section. It's clearly listed as 220
>>nF minimum as parameter D324.
>>
>>
>>Regards, Bob
>>
>>  
>>
>I've searched for that kind of information in different documents, but
>still didn't found that. Where can I find that kind of values? I've
>already searched in the datasheet of the chips, and the reference manual.


I'm using datasheet DS39632B.  Table 28-5 on page 372 ("USB voltage
regulator specifications") lists C sub USB as parameter D324. The
minimum value is 220 nF. No typical or max value is listed. The
comment on this parameter is "Must hold sufficient charge for peak
load with minimal voltage drop"


Regards, Bob

2005\11\16@005204 by Chen Xiao Fan

face
flavicon
face

>I'm using datasheet DS39632B.  Table 28-5 on page 372 ("USB voltage
>regulator specifications") lists C sub USB as parameter D324. The
>minimum value is 220 nF. No typical or max value is listed. The
>comment on this parameter is "Must hold sufficient charge for peak
>load with minimal voltage drop"
>
>Regards, Bob

Since the USB voltage regulator is a LDO (Low Dropout Regulator),
normally the capacitance and the ESR of the capacitor will
affect the stability of the LDO.

The following article may be a good reference.
http://www.national.com/nationaledge/jul02/article.html

I will suspect that the output capacitor for Vusb
should be okay if it is higher than 220nF as long as the ESR
is not so big. Therefore most ceramic capacitor (probably less
than 4u7 to lower than cost) or Tantalum capacitor (lower value
is generally cheaper, e.g. less than 6u8) with capacitance bigger
than 220nF will be okay. Apparently low ESR is okay in this case
even though some older LDOs have problems with ceramic capacitors.
Take note that Vusb is not meant to drive high current.

The sentence in DS39632B "An external 220nF (+/-20%) capacitor
is required for stability" is misleading. I guess that the
author mentioned +/-20% to mean that the tolerance of the
capacitor is not so important.

According to the Microchip Forum posts, some of the most
of encountered problem with USB enumeration problem are
the following:
1) wrong configuration words
2) missing Vusb capacitor
3) lousy Vdd power supply filtering
4) wrong firmware

Regards,
Xiaofan

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