LPC213x, analog port question.

Started by lp2000c December 23, 2004

The LPC213x has 16 pins which CAN be configured as an ADC input.
Does this mean that I can't apply more than 3.3V to any of these
pins, without corrupting ADC operation?

--- In , "Richard" <richas@y...> wrote:
>
> Note: 5V on any pin that CAN be configured as an ADC input will
> corrupt the ADC conversion values.
>
> Richard





An Engineer's Guide to the LPC2100 Series

On 23 Dec 2004 at 23:13, lp2000c wrote:

>
>
> The LPC213x has 16 pins which CAN be configured as an ADC input. Does
> this mean that I can't apply more than 3.3V to any of these pins,
> without corrupting ADC operation?

On a design I did, where I only wanted to use one of the ADC inputs, and connected
the other lines to 5V devices, I got absolutely garbage readings even though the actual
AD channel I was using never went above 3.3V. So it appears that the statement below
is correct.

Regards
Anton Erasmus > --- In , "Richard" <richas@y...> wrote:
> >
> > Note: 5V on any pin that CAN be configured as an ADC input will
> > corrupt the ADC conversion values.
> >
> > Richard >
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--
A J Erasmus




Hi
as far as I know the previous LPC devices had this problem but the
LPC2130 series does not. I heard it somewhere but have not had the
change to verify it.
Bob

--- In , "Anton Erasmus" <antone@s...> wrote:
> On 23 Dec 2004 at 23:13, lp2000c wrote:
>
> >
> >
> > The LPC213x has 16 pins which CAN be configured as an ADC input. Does
> > this mean that I can't apply more than 3.3V to any of these pins,
> > without corrupting ADC operation?
>
> On a design I did, where I only wanted to use one of the ADC inputs,
and connected
> the other lines to 5V devices, I got absolutely garbage readings
even though the actual
> AD channel I was using never went above 3.3V. So it appears that the
statement below
> is correct.
>
> Regards
> Anton Erasmus > > --- In , "Richard" <richas@y...> wrote:
> > >
> > > Note: 5V on any pin that CAN be configured as an ADC input will
> > > corrupt the ADC conversion values.
> > >
> > > Richard
> >
> >
> >
> >
> >
> >
> > ------------------------ Yahoo! Groups Sponsor
> > --------------------~--> Make a clean sweep of pop-up ads. Yahoo!
> > Companion Toolbar. Now with Pop-Up Blocker. Get it for free!
> > http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/dN_tlB/TM
> > --------------------------------~-
> > >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
>
> --
> A J Erasmus




I would be nice to see the actual ADC/IO "Schematic" so one could see what
on earth is going on...

Regards
lasse -----Original Message-----
From: lpc2100_fan [mailto:]
Sent: 27. december 2004 02:03
To:
Subject: [lpc2000] Re: LPC213x, analog port question.
Hi
as far as I know the previous LPC devices had this problem but the
LPC2130 series does not. I heard it somewhere but have not had the
change to verify it.
Bob

--- In , "Anton Erasmus" <antone@s...> wrote:
> On 23 Dec 2004 at 23:13, lp2000c wrote:
>
> >
> >
> > The LPC213x has 16 pins which CAN be configured as an ADC input. Does
> > this mean that I can't apply more than 3.3V to any of these pins,
> > without corrupting ADC operation?
>
> On a design I did, where I only wanted to use one of the ADC inputs,
and connected
> the other lines to 5V devices, I got absolutely garbage readings
even though the actual
> AD channel I was using never went above 3.3V. So it appears that the
statement below
> is correct.
>
> Regards
> Anton Erasmus > > --- In , "Richard" <richas@y...> wrote:
> > >
> > > Note: 5V on any pin that CAN be configured as an ADC input will
> > > corrupt the ADC conversion values.
> > >
> > > Richard
> >
> >
> >
> >
> >
> >
> > ------------------------ Yahoo! Groups Sponsor
> > --------------------~--> Make a clean sweep of pop-up ads. Yahoo!
> > Companion Toolbar. Now with Pop-Up Blocker. Get it for free!
> > http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/dN_tlB/TM
> > --------------------------------~-
> > >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
>
> --
> A J Erasmus

Yahoo! Groups Links



What chip was that? We know the problem exists on 2114/2124. The
question is whether it exists on 213x.

> On a design I did, where I only wanted to use one of the ADC
inputs, and connected
> the other lines to 5V devices, I got absolutely garbage readings
even though the actual
> AD channel I was using never went above 3.3V. So it appears that
the statement below
> is correct.
>
> Regards
> Anton Erasmus > > --- In , "Richard" <richas@y...> wrote:
> > >
> > > Note: 5V on any pin that CAN be configured as an ADC input will
> > > corrupt the ADC conversion values.
> > >
> > > Richard
> >
> >
> >
> >
> >
> >
> > ------------------------ Yahoo! Groups Sponsor
> > --------------------~--> Make a clean sweep of pop-up ads. Yahoo!
> > Companion Toolbar. Now with Pop-Up Blocker. Get it for free!
> > http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/dN_tlB/TM
> > ------------------------------
--~-
> > >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
>
> --
> A J Erasmus




On 27 Dec 2004 at 15:23, lp2000c wrote: > What chip was that? We know the problem exists on 2114/2124. The
> question is whether it exists on 213x.

This was using an LPC2292 chip.

> > On a design I did, where I only wanted to use one of the ADC
> inputs, and connected
> > the other lines to 5V devices, I got absolutely garbage readings
> even though the actual
> > AD channel I was using never went above 3.3V. So it appears that
> the statement below
> > is correct.
> >
> > Regards
> > Anton Erasmus
> >
> >
> > > --- In , "Richard" <richas@y...> wrote:
> > > >
> > > > Note: 5V on any pin that CAN be configured as an ADC input will
> > > > corrupt the ADC conversion values.
> > > >
> > > > Richard
> > >
> > >
> > >
> > >
> > >
> > >
> > > ------------------------ Yahoo! Groups Sponsor
> > > --------------------~--> Make a clean sweep of pop-up ads. Yahoo!
> > > Companion Toolbar. Now with Pop-Up Blocker. Get it for free!
> > > http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/dN_tlB/TM
> > > ------------------------------
> --~-
> > > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> > --
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>

--
A J Erasmus