Working dual-clock speeds
Dan Michaels email (remove spam text)
Roman Black wrote:
>Hi everyone. I got bored today (Sunday afternoon) and
>decided to have a crack at the question posed on the piclist
>a few weeks back, how to get two separate clock speeds on
>a PIC allowing the PIC to decide which clock speed it is
>using under software control. This provides an alternative
>to sleep mode with wakeups.
>I got it working fine! Only needs ONE schottky diode and ONE
>PIC output pin to switch speeds (or can be switched by any
>logic level signal).
>Here it is:
Can you see a similar "easy" way to something like this with
2 different "oscillator" signals [ie, PIC_pin+diode -vs- bulky
external switching logic]?
I want to use one of the programmable oscillator chips - namely
the ECS-300, which has divide ratios from 1/2 down to 1/256 - but
unfortunately the non-divided output comes off a different pin
from the divided output, so you still need a way to select
between the two signals. All in all, with this part, you can get
20Mhz, 10, 5, 2.5, ............, or 16Mhz, 8, 4, 2, 1, .5, .25,
........... - nice.
- Dan Michaels
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