Reading GPIO port on AT91SAM9g45

pankajcamb · **Joined:** Wed Mar 02, 2011 1:06 pm **Posts:** 4

HI there,

I am interfacing a 16-Bit ADC to AT91SAM9g45 with Embedded Linux OS. I have connected the ADC 16-Bit data bus to port c (PORTC15..PORT30). How can I read the port C or any port on this controller as a whole? Any help would be helpful..

Pankaj C

CptTitanic · **Joined:** Sat Oct 30, 2010 6:04 pm **Posts:** 784

Presumably you could write a driver, or mmap the PIO memory.

blue_z · **Posted:** Mon Mar 05, 2012 12:16 am

CptTitanic wrote:

Presumably you could write a driver, or mmap the PIO memory.

Agreed, those are your two choices. However, a device driver would be the preferred method of preserving the integrity & security of the Linux kernel. Mmapping in userland code is the quick & dirty method that is only tolerated on secure embedded platforms.

Regards

pankajcamb · **Joined:** Wed Mar 02, 2011 1:06 pm **Posts:** 4

Hi.. Thanks for your reply. I am indeed trying to write a driver for the same. But I driver module I don't know how to access the GPIO port as a parallel port.

What is the function used to do it.

Regards

Pankaj C

CptTitanic · **Joined:** Sat Oct 30, 2010 6:04 pm **Posts:** 784

pankajcamb wrote:

But I driver module I don't know how to access the GPIO port as a parallel port.

What is the function used to do it.

You'd read the PIO_PDSR register from the PIOC

This is an example GPIO driver, but you'll likely need to adapt the code to read 16-bits in a single operation.

http://www.cs.fsu.edu/~baker/devices/lx ... t91/gpio.c

Reading GPIO port on AT91SAM9g45

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