AnsweredAssumed Answered

Simple GPI expansion

Question asked by ChristianH on Oct 8, 2015
Latest reply on Oct 8, 2015 by AlClark

Hi,

 

I'm using the ADSP-21489 and need more GPIs (~15).

All DAI and DPI pins are already used by other functions, also FLAG0-3.

 

So I tried to map FLAG4-15 to AMI interface (DATA0-7, ADDR0-7).

Here it seems that the internal pull-up (ipu) resistor brings the flag pins to a HIGH state.

For electronical reasons it is not preferred to use an external pull-down below 20k (which would be necessary if I understood it correctly).

 

One option is to use AMI DATA0-15 but reading from them needs some more DSP cycles (setting all wait states etc. to the lowest possible option) which I would like to avoid.

 

Another option is to use PDAP port on AMI ADDR4-23. Here it seems that the ipu are not active because the level is LOW.

 

Can anybody send me a simple example how to read levels from via PDAP maybe without the need to set any clocking stuff on PDAP?

 

Any ideas welcome!

 

Thanks!

Christian

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