PIODC Multiplexing

Discussion around product based on ARM Cortex M4 core.

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myoung17
Posts: 6
Joined: Wed Nov 20, 2013 6:18 pm

PIODC Multiplexing

Thu Dec 04, 2014 7:16 pm

I'm trying to use the PIO Data Capture interface, but i do NOT need the enable pins PIODCEN1 and PIODCEN2.

The datasheet states "... writing the PCEN bit at 1 in PIO_PCMR, the I/O lines connected to the sensor clock, the sensor data, and the sensor enable signals are configured automatically as INPUTS."

Is there a way to re-configure PIODCEN1 and PIODCEN2 for different functions after setting PCEN?
myoung17
Posts: 6
Joined: Wed Nov 20, 2013 6:18 pm

Re: PIODC Multiplexing

Fri Dec 05, 2014 5:33 pm

Some extra info: i'm using SAM4SD32

So a quick test shows that setting PCEN doesn't take over PIODCEN1 and PIODCEN2.

Eg.

1. Setup TC1 to toggle PA15/ TIOA1, which is multiplexed with PIODCEN1. Initialize this first, with TIOA1/ MUXB selected by PIO.
2. Setup PIODC, initialize this second (calls PCEN=1). I believe there is no need to call any multiplexing commands from the PIO controller since setting PCEN automatically configures the pins as inputs.

-> Sure enough, TIOA1 continues to pulse and data is coming across PIODC by only using clock and data signals, cool.

So now, lets say i want to use some of the data pins on the PIODC bus. If i run the same test with TC2 toggling PA26/ TIOA2, it fails (stops toggling) after initializing PIODC.

Does anyone know if its possible for the PIO controller to take over I/O multiplexed with PIODC[7:0] when data capture is enabled (PCEN=1)? Are there more details available on the internal hardware of the PIODC interface?
jvb_s
Posts: 4
Joined: Thu Dec 04, 2014 2:49 pm

Re: PIODC Multiplexing

Fri Dec 05, 2014 8:49 pm

Hi,

This is a confirmation received some time ago from an atmel app. eng. that it is not possible to do it:

"When the parallel capture is enabled (PCEN bit at 1 in PIO_PCMR), the parallel capture module will take control of the I/O pins used for parallel capture and will be configured as inputs."

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