Lpc2000

To reduce power consumption in power down mode, I use PINSEL2 to 
disconnect the EMC and revert external memory bus to inputs. Since 
these are on P2 and P3 with internal pullups, I should see 3.3V 
correct? In actuality, I'm seeing them float around 2.2V. I've tried 
to reset the IOxDIR bits as inputs, but still no 3.3V. This is true 
even for CS1, 2 & 3 pins which are not connected to anything 
externally. Does anyone know what can cause this?

Thx

Tony

>To reduce power consumption in power down mode, I use PINSEL2 to
>disconnect the EMC and revert external memory bus to inputs. Since
>these are on P2 and P3 with internal pullups, I should see 3.3V
>correct? In actuality, I'm seeing them float around 2.2V. I've tried
>to reset the IOxDIR bits as inputs, but still no 3.3V. This is true
>even for CS1, 2 & 3 pins which are not connected to anything
>externally. Does anyone know what can cause this?
Often the impedance is very high in such a mode. I don't know the exact
circuit Philips uses and don't have a part here to try it out.
What is the resistance of your multimeter? Even with 10Megohms you may see a
significant voltage drop. Try to measure both against GND and against VCC.
This will show you if you measure the pin voltage correctly. Both values
added must be the same result as the absolute value of VCC minus GND.

A look in the datasheet done?!

Hope it helps.

regards -
Henry

<Schau auch mal auf meine Homepage www.ehydra.dyndns.info>
<u.a. Versand von Wasserflohzuchtansatz, Wasserpflanzen/-schnecken,
brasilianischer Sauerklee, Natron zum Backen/Baden, u.a.>
<Alternativ \ufffdber http://people.freenet.de/algenkocher>

I spoke to Philips Apps today, and was informed the memory bus will 
always go to high impedance, ignoring the fact the datasheet says 
pullups are there on these ports.

--- In lpc2000@yahoogroups.com, "otc_friend" <otc_friend@g...> wrote:
> >To reduce power consumption in power down mode, I use PINSEL2 to
> >disconnect the EMC and revert external memory bus to inputs. Since
> >these are on P2 and P3 with internal pullups, I should see 3.3V
> >correct? In actuality, I'm seeing them float around 2.2V. I've 
tried
> >to reset the IOxDIR bits as inputs, but still no 3.3V. This is 
true
> >even for CS1, 2 & 3 pins which are not connected to anything
> >externally. Does anyone know what can cause this?
> Often the impedance is very high in such a mode. I don't know the 
exact
> circuit Philips uses and don't have a part here to try it out.
> What is the resistance of your multimeter? Even with 10Megohms you 
may see a
> significant voltage drop. Try to measure both against GND and 
against VCC.
> This will show you if you measure the pin voltage correctly. Both 
values
> added must be the same result as the absolute value of VCC minus 
GND.

> 
> A look in the datasheet done?!
> 
> Hope it helps.
> 
> regards -
> Henry
> 
> <Schau auch mal auf meine Homepage www.ehydra.dyndns.info>
> <u.a. Versand von Wasserflohzuchtansatz, Wasserpflanzen/-schnecken,
> brasilianischer Sauerklee, Natron zum Backen/Baden, u.a.>
> <Alternativ über http://people.freenet.de/algenkocher>