Re: 8051 dead or what?

On Sun, 25 Jun 2006 10:52:12 +0100, the renowned Ian Bell
<ruffrecords@xxxxxxxxx> wrote:

Jim Granville wrote:

Alistair George wrote:

Ian Bell wrote:

Alistair George wrote:

Re HEF40106BT been there, tried that does not work in our use, which as
a very high gain oscillator.


You are using a hex schmitt trigger as a high gain oscillator?

Ian

Yes, in the original National app notes shows a schmitt trigger as an
oscillator. Variations between manufacturers have largely made that form
of use redundant.

This is curious - I take it you mean something other than the
standard, widely used 2 terminal RC Schmitt oscillator ( or the 3
terminal oscillator, which is more acurate but needs 3 gates of a 40106 )
?


I think he means in a crystal oscillator - ISTR this was a common way of
generating a microprocessor clock in the 80s but even then it was known to
be unreliable due to using a digital device in an analog mode.

Ian

IIRC, the 8048/8749 etc. NMOS microcontrollers used a ST in a Pierce
oscillator configuration. IIRC it was supposed to start up in RC mode
@ 50kHz or so and then transition to oscillating at the crystal
frequency. But there are potential problems (it might not make that
transition depending on parameters) and that configuration isn't seen
much these days.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@xxxxxxxxxxxx Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
.

Relevant Pages

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