Hi Kiste, 2011/1/12 Oliver Seitz <[email protected]>
> > - optional (solder jumpers) crystal & caps (internal clock could be > enough, and would allow dynamic clock speed management for low consumption > applications > > USB requires a crystal. Internal clock is not accurate enough. So USB > communication but no crystal won't do. > But when not using a USB capable PIC, you may get rid of crystal. Do you know the standard used with SMD crystal ? Does it worth it to use a SMD xtal or is HC49 form-factor enough ? I'm asking because HC49 is much more easier to find. Also, some PIC can have two clock sources, one for USB peripheral, another one for PIC itself. When plugged to a PC, the board can exchange data, when unplugged, it could go to lower speed and save battery life. > BTW, I wonder how Jal deals with clock speed runtime modification... > > I don't think it does at all. Everything that has some timing in it (like > delay, serial...) only works correct at the specified clock speed. If you've > specified 4MHz clock, but run at 32kHz, a _usec_delay(1000) won't delay 1 > ms, but 125ms. > I know, pragma clock can be defined only once. But is this only about _usec_delay ? I can't anothe issue, but I may be wrong. Otherwise it could be possible to re-define _usec_delay in some way (...) and have multiple implementation depending on selected speed. Cheers, Seb -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
