I am trying to decide which pins of the AT91SAM7S64 would server me best for general IO.

For example I have my reset and data/command lines of a particular part going to PA17 and PA18. ( But these pins are also A/D's!!) The datasheet states that PIO controller can be multiplexed so that the pins have different functions. With this in mind I am worried I might cause a problem by not understanding how the pins are working.

Thanks for the clarification.

-Henk

Hi,

any IOs which are multiplexed with the PIO controller can be drived by on-chip peripherals or used as standard general purpose IOs.
For example, the ADC has 8 inputs and 4 of them are multiplexed so they can be used as normal IOs except if the corresponding channel is enabled. In this case the IOs will be driven by the ADC. You have to take care to not enable the ADC channels used as normal IOs (PA17 and PA18 in your case).

Hope this help.

Rgds
JP

JP! Oh yeah! I love it man! Thanks for the info!

Is it possible to test to see if a pin is high or low without using the A/D? For example if I have 4.5V coming in from the USB port I want to test to see if that voltage is present at a partcular pin.

Also do the logicl levels below seem correct? All the inputs/outputs are ttl right?

Outputs
----------
Logic 0,
output voltage VCC = min - - Iout= 16 mA -- 0.4 V

Logic 1,
output voltage VCC = min - - Iout= - 400 mA 2.4 -- V

Inputs
--------
Logic 1
input voltage VCC = min 2.0 -- V

Logic 0,
input voltage VCC = min -- 0.8 V


THANK YOU VERY MUCH!

-Henk

Hi,

regarding output current, there is only 4 pads called high current pads which can draw 16mA, other IOs can draw 8mA only.

Rgds
JP

Setting the state of an output pin seems straight forward. But for a general io pin how do I detect the status (high or low) without using the ADC?

Thanks.

-Henk