TMDXEVM8148: GPIO Numbers for GPIO pins in J17 GPIO Connector

Aravind Siddappaji

Prodigy 160 points

Dear Support Staff,

We are using TMDXEVM8148 evaluation board for our development. We need to use GPIO pins in J17 GPIO Connector

(CSI interface). To program this pin let us know what is the GPIO number to be used in gpio_request() function.

In J17 connector we need to use: Pin #4 & Pin #5 as GPIO signal out. Let me know if this is possible and what are the

GPIO pin numbers to be used in gpio_request() function.

Thanks & Regards,

Aravind S

Lead Engineer

Sasken Comm Tech Ltd

over 12 years ago

0 Biser Gatchev-XID over 12 years ago

TI__Guru**** 393215 points

Hi Aravind,

Do you mean J17 on the expansion board (RJ-45 connector)? If this is the one you mean pin 4 is GP0[29] and pin 5 is GP3[18].

0 Aravind Siddappaji over 12 years ago in reply to Biser Gatchev-XID

Prodigy 160 points

Hi Staff,

Thanks for the reply.

Yes, it is J17 on expansion board. Please confirm if I can use the Pin4 & Pin5 as below.

gpio_request(29) /* for pin#4 .i.e. GP0[29] ==> gpio number = 29*/

gpio_request(114) /* for pin $5 .i.e. GP3[18] ==> gpio number = 32*3+18 = 114 */

Thanks & Regards,

Aravind S

0 Pavel Botev over 12 years ago in reply to Aravind Siddappaji

TI__Guru**** 170625 points

Hi Aravind,

According to our GPIO driver user guide, you should pass two parameters to the gpio_request function:

http://processors.wiki.ti.com/index.php/TI81XX_PSP_GPIO_Driver_User_Guide#Kernel_Level

Allocate memory to GPIO line, can be achieved by doing gpio_request()

err = gpio_request(30, "sample_name");

Some examples from our TouchScreen Driver User Guide:

http://processors.wiki.ti.com/index.php/TI81XX_PSP_TouchScreen_Driver_Guide

ret = gpio_request(gpio, "lcd_power");

error = gpio_request(GPIO_TSC, "ts_irq");

Regards,
Pavel

0 Aravind Siddappaji over 12 years ago in reply to Pavel Botev

Prodigy 160 points

Hi Staff,

To check GPIO connection J17 (pin #4 : GP0[29] and pin #5: GP3[18], the below

was tried. But the voltage at PIN#4 & PIN#5 are always at around 0.6 Volts. The

value of 0/1 set for GP0[29] & GP3[18] using below process is not having any effect

on the voltage level at the pin #4/ pin #5 of J17 GPIO connector. Please provide your

inputs to use the pins.

/* PIN #4 */
echo 29 > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio29/direction
echo 1 > /sys/class/gpio/gpio29/value
echo 0 > /sys/class/gpio/gpio29/value

/* Pin #5 */
echo 114 > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio114/direction
echo 1 > /sys/class/gpio/gpio114/value
echo 0 > /sys/class/gpio/gpio114/value

Thanks & Regards,

Aravind S

0 Aravind Siddappaji over 12 years ago in reply to Pavel Botev

Prodigy 160 points

Hi Staff,

To check GPIO connection J17 (pin #4 : GP0[29] and pin #5: GP3[18], the below

was tried. But the voltage at PIN#4 & PIN#5 are always at around 0.6 Volts. The

value of 0/1 set for GP0[29] & GP3[18] using below process is not having any effect

on the voltage level at the pin #4/ pin #5 of J17 GPIO connector. Please provide your

inputs to use the pins.

/* PIN #4 */
echo 29 > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio29/direction
echo 1 > /sys/class/gpio/gpio29/value
echo 0 > /sys/class/gpio/gpio29/value

/* Pin #5 */
echo 114 > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio114/direction
echo 1 > /sys/class/gpio/gpio114/value
echo 0 > /sys/class/gpio/gpio114/value

Thanks & Regards,

Aravind S

0 Pavel Botev over 12 years ago in reply to Aravind Siddappaji

TI__Guru**** 170625 points

Hi Aravind,

Can you provide me the value of the PINCNTL59 register, after you execute the two commands:

echo 29 > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio29/direction

Can you provide me the value of the PINCNTL226 register, after you execute the two commands:

echo 114 > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio114/direction

Regards,

Pavel

0 Aravind Siddappaji over 12 years ago in reply to Pavel Botev

Prodigy 160 points

Hi Staff,

The values of PINCNTL59 and PINCNTL226 were checked in below scenarios and the

result is mentioned below:

echo 29 > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio29/direction

after this value of PINCNTL59 = 0x40001

echo 114 > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio114/direction

after this value of PINCNTL226 = 0x50004

Please let know how to proceed futher to enable Pin #4/#5 of J17 to work as output GPIO's

(GP0[29] & GP3[18]).

Thanks & Regards,

Aravind S

0 Pavel Botev over 12 years ago in reply to Aravind Siddappaji

TI__Guru**** 170625 points

Hello,

There is a note inside the http://processors.wiki.ti.com/index.php/TI81XX_PSP_GPIO_Driver_User_Guide :

Note: GPIO's which are used already in the drivers can not be control from sysfs, unless until driver export that particular pin.

I suspect this is causing the issue. You can try to set the GPIO pins from inside the linux kernel, check below how:

http://processors.wiki.ti.com/index.php/TI81XX_PSP_User_Guide#TI814X.2FTI813X

Regards,

Pavel

0 Aravind Siddappaji over 12 years ago in reply to Pavel Botev

Prodigy 160 points

Hi Staff,

As per the description in http://processors.wiki.ti.com/index.php/TI81XX_PSP_User_Guide#TI814X.2FTI813X,

the below was done used as boot argurment :

Try1: omap_mux=OMAP_PIN_OUTPUT.gpio0_29=0,OMAP_PIN_OUTPUT.gpio3_18=0

Try2: omap_mux=OMAP_MUX_MODE1.gpio0_29=0,OMAP_MUX_MODE4.gpio3_18=0

After the bootup, in both cases, at Pin#4/Pin#5 for J17, the voltage level was not 0V. With a Pullup resistor, the voltage was 3.7 V.

Please let me know further actions to use Pin#4/Pin#5 of J17 as GPIO output.

Regards,

Aravind S

0 Pavel Botev over 12 years ago in reply to Aravind Siddappaji

TI__Guru**** 170625 points

Aravind,

Make the following modifications in {EZSDK}/board-support/linux-2.6.37-psp04.04.00.01/arch/arm/mach-omap2/board-ti8148evm.c

#ifdef CONFIG_OMAP_MUX
static struct omap_board_mux board_mux[] __initdata = {
   TI814X_MUX(MLB_SIG, OMAP_MUX_MODE7),
   TI814X_MUX(VOUT1_R_CR8, OMAP_MUX_MODE7),
   { .reg_offset = OMAP_MUX_TERMINATOR },
};

Then:

1. Choose default kernel configuration for the platform.

$ make CROSS_COMPILE=arm-none-linux-gnueabi- ARCH=arm ti8148_evm_defconfig

2. To view configuration interactively:

$ make CROSS_COMPILE=arm-none-linux-gnueabi- ARCH=arm menuconfig

Enable GPIO sysfs support:

Device Drivers  ---> GPIO Support  ---> /sys/class/gpio/... (sysfs interface)

3. Initiate the build:

$ make CROSS_COMPILE=arm-none-linux-gnueabi- ARCH=arm uImage

Use the newly generated uImage from linux-2.6.37-psp04.04.00.01/arch/arm/boot/uImage to boot the system.

When boot up successfully, make:

root@dm814x-evm:~# echo 29 > /sys/class/gpio/export
PM: Adding info for No Bus:gpio29
root@dm814x-evm:~# echo "out" > /sys/class/gpio/gpio29/direction
root@dm814x-evm:~# echo 114 > /sys/class/gpio/export
PM: Adding info for No Bus:gpio114
root@dm814x-evm:~# echo "out" > /sys/class/gpio/gpio114/direction

Then check the /sys/class/gpio folder, it should contain the gpio29 and gpio114:

root@dm814x-evm:/sys/class/gpio# ls
export gpio128 gpio31 gpiochip128 gpiochip64 unexport
gpio114 gpio29 gpiochip0 gpiochip32 gpiochip96

Then check the output direction is set correctly:

root@dm814x-evm:/sys/devices/virtual/gpio/gpio29# cat direction
out

root@dm814x-evm:/sys/devices/virtual/gpio/gpio114# cat direction
out

Does this work for you?

Regards,

The Staff

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TMDXEVM8148: GPIO Numbers for GPIO pins in J17 GPIO Connector