Lpc2000

Your explanation is clear as glass.

Thanks,
Ed

P.S.: The User Manual is wrong, or confusing at best.  It says:

"Note that these analog inputs are always connected to their pins, 
even if the Pin Multiplexing Register assigns them to port pins."

That seems to imply that the affect that applying 5V to these pins 
will have on the A/D converter is not be dependent on the setting of 
the Pin Multiplexing Register.

Also:

"If the A/D converter is not used in an application then the pins 
associated with A/D inputs can be used as 5V tolerant digital IO pins"

This says to me that you can only use them for 5V if the A/D 
converter "is not used."  However, if the converter is used, but some 
pins (with 5V) are mapped as i/o, there will still be a problem.


--- In lpc2000@yahoogroups.com, "philips_apps" <philips_apps@y...> 
wrote:
> 
> Ed see below
> 
> if you still have open questions I will do my best to answer them 
> 
> Robert
> 
> 
> --- In lpc2000@yahoogroups.com, "edmiller613" <edmiller613@y...> 
wrote:
> > 
> > The LPC213x User Manual contains the following Note in Table 143:
> > 
> > "Note: if the A/D converter is used, signal levels on analog 
input 
> > pins must not be above the level of V3A at any time. Otherwise, 
A/D 
> > converter readings will be invalid."
> > 
> > Are you saying that the User Manual is wrong?
> > 
> 
> In all devices with ADCs before the LPC2130 series, a signal >Vdd on
> any pin "that could be used as analog input" screws up the ADC even 
if
> it is defined as digital input. On the LPC2130 series the digital
> input can now exceed Vdd. If the input is configured as analog input
> you violate the spec (results in ADC wrong results) if exceeding 
Vdd.
> Summary: if 5V on an analog input pin -> results corrupted, if 5V 
on a
> pin that could be analog in but is configured as digital in -> no
> corruption 
> 
> Confused?  Everything clear?
>