Re: 18F452 RC oscillator mode

On 2 Abr, 15:38, James Beck <j...@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
In article <a354520c-4cc1-46be-aba7-5b33247faf30
@r9g2000prd.googlegroups.com>, sebastiase...@xxxxxxxxx says...

Dave : you say

??? Add these two together and there's your period of
oscillation ???

How can you add Ohms to Farads ?
What units is the result ?

I need a "normal" frequency, lets say 1 or 5 or 10 MHz ...

Thanks. Seb.

I think the point is that your frequency will not be "normal" it will
vary, from part to part, by temperature, and by variations of Vdd.
Anyway, if you look at Figure 23-12 on page 294 of the documentation,
there is a graph that shows frequency VS Vdd and 'R' value.

Jim

JIM : do you think it is normal
a) to have the "RC oscilator" on page 18,
and
b) have the drawing on page 294

??????????

Without any "pointer", no text, no formula ??? ok.

Anyway, thanks a lot for the pointer to the page.
if C = 20 pF and R = 3K3 then f = 3,5 MHz.

Shall try it next weekend.

Cheers ! Seb.
.

Relevant Pages

  • Re: 18F452 RC oscillator mode
    ... vary, from part to part, by temperature, and by variations of Vdd. ... The table of contents lists "23.0 DC and AC Characteristics Graphs and ... thanks a lot for the pointer to the page. ... I think a cheap ceramic resonator would be cheap insurance. ...
    (comp.arch.embedded)
  • Re: 18F452 RC oscillator mode
    ... oscillation ??? ... How can you add Ohms to Farads? ... vary, from part to part, by temperature, and by variations of Vdd. ...
    (comp.arch.embedded)