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Pinguino sans quartz - Printable Version

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Pinguino sans quartz - Callmea - 13-03-2014

Bonsoir,

Est-il possible de recompiler (ou télécharger) le bootloader PIC18F4550 (en changeant les config bits), afin de le faire fonctionner sur un uc dépourvu de quartz? dans le datasheet j'ai cru lire qu'avec un pll multiplicateur on pouvait se passer d'un quartz? les scripts python/ et ou l ide seraient-ils compatibles?

Certes je me doute que la précision serrait moins bonne, mais pour certains montage cela pourrait être pratique et economique Rolleyes


RE: Pinguino sans quartz - xapon66 - 13-03-2014

(13-03-2014, 01:30 AM)Callmea Wrote: Bonsoir,

Est-il possible de recompiler (ou télécharger) le bootloader PIC18F4550 (en changeant les config bits), afin de le faire fonctionner sur un uc dépourvu de quartz? dans le datasheet j'ai cru lire qu'avec un pll multiplicateur on pouvait se passer d'un quartz? les scripts python/ et ou l ide seraient-ils compatibles?

Certes je me doute que la précision serrait moins bonne, mais pour certains montage cela pourrait être pratique et economique Rolleyes

Bonjour Callmea,

Il existe quelques PIC dont l'oscillateur interne est suffisamment stable pour permettre le bon fonctionnement de l'USB.
Le PIC18f47j53 en fait partie. Cela tombe bien il est disponible dans la boutique Pinguino. Smile


RE: Pinguino sans quartz - pinguPlus - 13-03-2014

Bonjour Callmea,
(13-03-2014, 01:30 AM)Callmea Wrote: Est-il possible de recompiler (ou télécharger) le bootloader PIC18F4550 (en changeant les config bits), afin de le faire fonctionner sur un uc dépourvu de quartz?

my french is very, very rusty, so replying in english Smile

Here you can find all available bootloaders.

The hex files using the internal oscillator are labeled as *_INTOSC.hex.

Oliver


RE: Pinguino sans quartz - trollpatsch - 13-03-2014

Sorry for replying in English.

The main question upon any 'crystal-free' designs is: does the clock precision fulfill the USB requirements, as (in most cases) USB would be considered a pinguino core feature.

There are some (quite new) PICs that are USB-capable from internal clock "by design". The manufacturer guarantees xtal-free full speed USB over the full temperature range: 18(L)FxyK50 (x=2/4, y=4/5) and 16(L)F145x. There may be others (e.g PIC24 types with a certain letter combination, I cannot recall).

There are other PICS where you can NOT EVEN SELECT an internal clock of 48MHz, needed for the USB engine: quite obviously, the manufacturer does not WANT you to even try this: e.g. 18(L)F1xK50.

And there are PICs somewhat in between: the 18(L)F..J50/J53 seem to work quite well on internal clock, at least at "normal room temperature".

The SECOND question is: Will it simply work, concerning my own (maybe very limitted) requirements (mainly: upon temperature range). Some people would consider asking this question an outrage. Main problem here is the statistical spread. If one or some samples do work: what could this tell about ALL (or the vast majority) of them? Of course, if you are just interested in YOUR own sample(s), you can simpy try them out. But don't blame the manufacturer if you did not stick to the specs and run into troubles, then.

I recently had an enlightening chat with a Microchip engineer about this "3rd type" USB-PICs at Embedded World Trade Fair. It seems the 18..J50/J53 chips are factory calibrated to work 'almost reliably' at 21 °C (centigrades) on FULL speed. But they are guaranteed to work over full temperature range at low speed! So maybe a try-fast-or-else-step-down strategy could by an interesting approach? As far as I can recall, he was NOT talking of USB 1.1 - since both, USB2 and USB1.1 support low (1.5MBit/s) and full speed (12MBit/s).

Regis already supplies a huge number of bootloaders at

http://code.google.com/p/pinguino32/source/browse/#svn%2Fbootloaders%2F8%2Fusb%2Fv4.x%2Fhex

Just look out for the suffix _INTOSC.HEX to get an impression whether a certain USB-PIC does (1st type) or might (3rd type) support xtal-less designs. (You cannot distinguish type1 from type3 chips from this list, of course.)

Sorry Oliver, I just was too slow ... (Edit: typos)


RE: Pinguino sans quartz - pinguPlus - 13-03-2014

(13-03-2014, 10:37 AM)trollpatsch Wrote: The main question upon any 'crystal-free' designs is: does the clock precision fulfill the USB requirements, as (in most cases) USB would be considered a pinguino core feature. [...]

Interesting remarks. Can I put your post in the wiki? Maybe the FAQ is the right place for this.

Oliver


RE: Pinguino sans quartz - trollpatsch - 13-03-2014

Of course you can!
I noticed your bootloader link is not the same as mine: do they resolve to the same physical folder? And if not, why, and which one should be used then?


RE: Pinguino sans quartz - pinguPlus - 13-03-2014

(13-03-2014, 11:22 AM)trollpatsch Wrote: I noticed your bootloader link is not the same as mine: do they resolve to the same physical folder? And if not, why, and which one should be used then?

Your link points to the hex folder of the bootloader directory.
/svn/bootloades/8/usb/v4.x/hex/

My link references the extra folder of the IDE.
/svn/ide/x.4/extra/bootloaders/8bit/

The hex files seems to be the same, but the directories are not identical. There are three more files in the extra/bootloaders folder.

IMHO we should use the extra folder.

Oliver


RE: Pinguino sans quartz - regis - 15-03-2014

Bootloaders are the same.
I just put a copy of them in the "extra" folder to make them available offline.
Note that this folder doesn't exist anymore in Pinguino IDE v11.
All bootloaders will now be there : https://github.com/PinguinoIDE/pinguino-bootloaders


RE: Pinguino sans quartz - pinguPlus - 15-03-2014

(15-03-2014, 11:49 AM)regis Wrote: Note that this folder doesn't exist anymore in Pinguino IDE v11.
All bootloaders will now be there : https://github.com/PinguinoIDE/pinguino-bootloaders

OK, thanks. I have corrected this in the wiki article.

Oliver


RE: Pinguino sans quartz - Callmea - 16-03-2014

Hello,

I thank you for yours answers Smile

I think about it for some projects who do'nt need a clock accuracy even the usb transfert is slow, it isn't a problem for me.