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[Discuss-gnuradio] Using Sysfs to set a GPIO in Overo

From: Sameh Yassin
Subject: [Discuss-gnuradio] Using Sysfs to set a GPIO in Overo
Date: Wed, 2 May 2012 05:16:03 -0700 (PDT)

Dear P. Balister,
I found that tutorial which explains very well how to create a GPIO folder and set its direction

I searched for the misc GPIOs to make sure they are free and I'm pretty sure that over_gpio0 and overo_gpio170 are free. the are not used at all inside the code.  I connected them to debug led0 and debug_led1 and used echo 1> /sys/class/gpio/gpio0/value after setting the direction but nothing at all, the two debug leds are off.

Another question, what is the difference between gpio0 and gpiochip0 found at /sys/class/gpio  
S. Yassin
HW Engineer

From: Philip Balister <address@hidden>
To: Sameh Yassin <address@hidden>
Cc: GNURADIO <address@hidden>
Sent: Wednesday, May 2, 2012 1:33 PM
Subject: Re: [Discuss-gnuradio] E100 - Interface between OMAP3 and FPGA

On 05/01/2012 04:28 AM, Sameh Yassin wrote:
> Hello Dear ,
> I used the first link to use overo GPIOs on the E100 to communicate with the SPARTN3AN FPGA.
> I'm  doing the following:
> 1- I chose an empty GPIO input to the FPGA (for example overo_gpio22).
> 2- I modified the FPGA image so that debug_led1 = over_gpio220
> 3- I'll set and clear overo GPIO using the bash shell as I read in the first link that u recommended.
> The problem:
>  Although the following gpios are free on the FPGA. There are other gpios  valid on the overo. Srictly speaking
> The free GPIOs on the overo
> $ address@hidden:/sys/class/gpio# ls
> exportgpio16 gpio168    gpiochip128  gpiochip192  gpiochip64  unexport
> gpio15gpio164  gpiochip0  gpiochip160  gpiochip32  gpiochip96

It looks like you are running an older version of uhd, which suggests an
older kernel version. The older driver claimed a few extra gpio's for
testing purposes.

I see:

address@hidden:~# ls /sys/class/gpio/
export    gpio16@  gpio173@    gpiochip128@  gpiochip32@  unexport
gpio114@  gpio164@  gpio175@    gpiochip160@  gpiochip64@
gpio15@  gpio168@  gpiochip0@  gpiochip192@  gpiochip96@

Note the extra gpio's exposed to user space. These are used by uhd for
signaling and configuring the clock generator.


> The free gpios at the FPGA found at u1e.v
> input overo_gpio0, input overo_gpio14, input overo_gpio21, input overo_gpio22,  // Misc GPIO
> input overo_gpio23, input overo_gpio64, input overo_gpio127, // Misc GPIO
> input overo_gpio176, input overo_gpio163, input overo_gpio170, // Misc GPIO
> Is that normal of I did something wrong at the kernel at the overo?
> Regards,
> S. Yassin
> HW Engineer
> ________________________________
>  From: Philip Balister <address@hidden>
> To: Sameh Yassin <address@hidden>
> Cc: "address@hidden" <address@hidden>
> Sent: Saturday, April 28, 2012 2:18 PM
> Subject: Re: [Discuss-gnuradio] E100 - Interface between OMAP3 and FPGA

> On 04/28/2012 08:07 AM, Sameh Yassin wrote:
>> Dear all,
>> I need to send data from the OMAP3 to the Spartan3an FPGA. As I understand ,from the wiki and presentations,  there are two ways to communicate namely; using setting_reg and GPIO.  The second way seems easier so I'll try it first.
>> I intend to set or clear the free GPIOS on the Spartan FPGA such as over_gpio_22. I  added the following code to the example tx_waveforms.cpp.
>>          static struct gpio gpio_test = { 22, GPIOF_OUT_INIT_LOW, "OVERO_GPIO_22" };
>> gpio_set_value(22,1);
>> //set gpio22 which is connected to pin IO_L30N_0
>> I tried to compile then I got the error that can't find GPIO.h.
>> My question: did I use the correct high level function or I used a "lower level" that is used to implement the function?
> This is the easiest way to toggle gpio's from userspace.
> http://wiki.gumstix.org/index.php?title=GPIO#Accessing_GPIO.27s_from_userland
> Also:
> http://elinux.org/GPIO
> The kernel on the e100 already supports the sysfs entries for gpio's.
> (UHD uses it)
> Philip
>> Regards,
>> S. Yassin
>> _______________________________________________
>> Discuss-gnuradio mailing list
>> address@hidden
>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

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