Re: [Flashforth-devel] strange answer from UART

[Peter J. <pe...@me...>]

Thomas,
Looking at sections 2.x in the datasheet, it seems to me that the PLL is 
not exclusively for crystals and resonators; it available to the 4 and 
8MHz internal oscillator.  Figure 2.8 shows it limited to these 
options.  That figure is (presumably) a simplified diagram and I don't 
know enough to be sure what would happen if you set OSC=HSPLL and drive 
the OSC1 pin with your external oscillator.  Would you be abusing the 
silicon?  You wouldn't be able to use RA6 as an IO pin but that might be 
OK since you don't show it in use on your diagram.
Peter J.


On 17/03/14 21:25, Thomas Buschhardt wrote:
> Dear Peter, is HSPLL actually for crytals and resonators? I use a 
> oszillator (clock) see link in the first mail. But of course this 
> evening I'll give it a try.
> Thomas
>
>
> 2014-03-17 11:54 GMT+01:00 Peter Jacobs <pe...@me... 
> <mailto:pe...@me...>>:
>
>     Can you simply turn on the PLL (OSC = HSPLL) to get a 16MHz sys-clock
>     frequency?  I've quite happily run a PIC18F2520 at 38400 baud with a
>     4MHz crystal and the PLL active.
>     Peter J.
>
>
>     On 17/03/14 18:33, Herman Attila wrote:
>     > Hi Thomas,
>     >
>     > Maybe your problem comes from low Osc-frequency/baudrate ratio.
>     Using 4MHz osc freq. the controller generates the 38400kbs with
>     10% error. Try to use higher osc freq. or lower baudrate.
>     Otherwise I recommend you to use 18F26K22 or other xxk22
>     controllers. They have well configurable internal oscillator and
>     have several further excellent features.
>     >
>     > BR
>     > Attila
>     >
>     > ----- Eredeti üzenet -----
>     > Feladó: Thomas Buschhardt <bus...@gm...
>     <mailto:bus...@gm...>>
>     > Dátum: Hétfo", Március 17, 2014 8:32
>     > Tárgy: [Flashforth-devel] strange answer from UART
>     > Címzett: Fla...@li...
>     <mailto:Fla...@li...>
>     >
>     >
>     >> Dear Mikael and mailing listeners,
>     >>
>     >> I desperated, I got some strange signs back from the PIC. In my
>     >> despair - I
>     >> installed even MS Windows, to see whether my usb-2-serial
>     adapter is broken
>     >> - but the program "Hyperterminal" shows the same results.
>     >>
>     >> Here is my configuration:
>     >>
>     >> PIC18F2620
>     >> 4 MHz Oscillator Link to
>     >> Oszillator<>
>     >> MAX232
>     >> FD-USB2Serial-Adapter
>     >>
>     >> The programing - process runs well with my PICKIT2. When the
>     PIC gets
>     >> power
>     >> its send the same strange signs, and if I blind input "1 2 3"
>     (to the
>     >> stack) in the terminal, I got a answer - that could be the
>     right one.
>     >> --snip--
>     >> 38400 -  8 - N - 1
>     >> ¦¬¡³¸¦¯²´¨ .Z(° °©£±~ S( S('
>     >> ¦¬¡³¸¦¯²´¨ .Z(° °©£±~ S( S('
>     >> ¦¬¡³¨¦¯²´¸ .Z(° °©£'¸ S( S('
>     >> ± ² ³ ± ² ³ Y" S(
>     >> --snip--
>     >> Here I restart 3 times the PIC and input "1 2 3" and get back
>     "± ² ³ Y"
>     >> S(".
>     >>
>     >> I changed the baudrate, oszillator frequency, the oscillator
>     selection
>     >> bits
>     >> - without success.
>     >> I hope I do some configuration mistakes, so please help me.
>     >>
>     >> The schematics for my hw-configuration, the (binary) log-file
>     of the
>     >> terminal and my changed configurations-files you can find here
>     as zip
>     >> file.
>     >>
>     >>
>     >>
>     >>
>     >> If you need more informations, please drop me a mail.
>     >>
>     >> Greetings Thomas
>     >>
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