Lpc2000

1) You can use external memory interface pins as GPIO.
2) You can check max input current of a pin under "absolute maximum ratings" 
in the datasheet. Use a series resistor to limit the input current. The 
resistor should be low enough not to degrade switching characteristics 
because of the I/O capacitances/inductances and high enough to limit the 
input current when 5V or whatever the voltage is applied to the input. 
Usually the max input current is between 5-10 mA. For instance, a 2K series 
resistor would limit the input current to 2.5mA when 5V is applied. Assuming 
this is protect the input from a transient condition, you should be fine. 
But if the switching speed is high then 2K resistor will drastically affect 
rise and fall times and will add propagation delay.
It is totaly up to your application. But the idea is it is not the voltage 
that destroys the input but the current.

Kerem




----- Original Message ----- 
From: "Zdravko" <bodhisatva@...>
To: <lpc2000@yahoogroups.com>
Sent: Tuesday, December 21, 2004 11:41 AM
Subject: [lpc2000] LPC2214 questions


>
>
> Hello,
> I am going to use LPC2214.
> I have some questions which are not clear for me in the User Manual.
>
>
> 1) Can I use the not used external memory bus address lines as GPIO
> (A0 and A1 are directly mentioned in the UM but the others not)?
> 3) What are the limiting values of the voltage on the pins when the
> 3.3V for the external rail is not present(The 1.8V for the core will
> be on all the time)?
>
> Thank you very much and Happy Holidays.
>
> Regards
> Zdravko
>
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> Yahoo! Groups Links
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