Re: [Flashforth-devel] flashforth on p18f4550 - No usb?

[Mikael N. <mik...@pp...>]

Hi Scott.
Great that it works !

So if you want you can make the CPU run slower with the CPUDIV.
PLLDIV must be set according to what kind of XTAL you have.
USBDIV should always be 2
The clock constant tells how fast the CPU is running.
It is needed for setting up the 1 ms timer and for configuring
the UART baud rate.

Did you have any special project in mid for FlashForth.

For the 4550 and cousins, here are a few examples
for full speed USB.

config PLLDIV = 1           ; 4 MHz XT xtal
config PLLDIV = 2           ; 8 MHz XT xtal
config PLLDIV = 3           ; 12 MHz XT xtal
config PLLDIV = 4           ; 16 MHz XT xtal
config PLLDIV = 5           ; 20 MHz XT xtal

config CPUDIV = OSC1_PLL2   ; 48 MHz cpu clock
constant clock=d'48000000'

config CPUDIV = OSC2_PLL3   ; 24 MHz cpu clock
constant clock=d'24000000'

config CPUDIV = OSC3_PLL4   ; 16 MHz cpu clock
constant clock=d'16000000'

config CPUDIV = OSC4_PLL6   ; 8 MHz cpu clock
constant clock=d'8000000'

config USBDIV = 2           ; USB clock from 96 MHZ PLL divided by 2


Cheers
Mike