The set up:
I have i.MX53 module mounted on a custom board. On the custom board there are peripherals such as GPS, GPSR module, LEDs etc. It is running Linux 2.6.35.3.
The goal is to start the GPS module. To do so I have to set logical high on certain pins (GPIO2_31 and USER_UI2).
Under the directory /sys/class/gpio/ I have:
gpiochip0
gpiochip128
gpiochip160
gpiochip192
gpiochip32
gpiochip64
gpiochip96
As I understand from the from the documentation the number after gpiochip is determined by the formula "<GPIO Instance – 1> × 32 + <GPIO Port number>" What is "Instance", the actual pin on the chip? And how to determine the "Port number"?
Lets say that i have configured the GPIO pin. In the documentations is writtren "echo 0 > /sys/class/gpio/gpio199/value" to set the value of the pin.
But this is the result:
root@freescale /$ echo 1 > /sys/class/gpio/gpiochip64/value
-sh: /sys/class/gpio/gpiochip64/value: No such file or directory
Under the /sys/class/gpio/gpiochip64/ directory there is only this:
| -r--r--r-- | 1 root | root | 4096 Jan 1 02:50 base |
| -r--r--r-- | 1 root | root | 4096 Jan 1 02:50 label |
| -r--r--r-- | 1 root | root | 4096 Jan 1 02:50 ngpio |
| drwxr-xr-x | 2 root | root | 0 Jan 1 02:50 power |
| lrwxrwxrwx | 1 root | root | 0 Jan 1 02:50 subsystem -> ../../../../class/gpio |
| -rw-r--r-- | 1 root | root | 4096 Jan 1 00:00 uevent |
What am I doing wrong? Any other documentation or example to read?
Source:
i.MX53 System Development User’s Guide (MX53UG Rev.1 3/2011)
P.S. I am new to embedded linux development, any help would be appreciated.
