ADLINK Industrial Pi Wiki

GPIO Utility on I-Pi SMARC LEC-EL

This document provides detailed instructions for utilizing the gpio pins on the I-Pi SMARC LEC-EL module based on Ubuntu.

Prerequisites

• GPIO libraries are included with our image by default.
• Power up the targeted device with all the necessary cables, such as HDMI, keyboard, mouse, and ethernet cable.

Utilizing the GPIO Pins with Linux

• Open the terminal and type the following command to navigate to gpio

  cd /sys/class/gpio

• The /sys/class/gpio can only be accessed as root by default, so log in as root.

  sudo su 

  

• To view the details of Gpiochip.

  $ gpiodetect
  
  root@adlink-LEC-EL:/home/adlink# gpiodetect
  gpiochip0 [INTC1020:00] (67 lines)
  gpiochip1 [INTC1020:01] (113 lines)
  gpiochip2 [INTC1020:03] (47 lines)
  gpiochip3 [INTC1020:04] (80 lines)
  gpiochip4 [INTC1020:05] (8 lines)
  root@adlink-LEC-EL:/home/adlink# 
  
  	(or)
  	
  $ cat /sys/kernel/debug/gpio 
  
  root@adlink-LEC-EL:/home/adlink# cat /sys/kernel/debug/gpio 
  gpiochip4: GPIOs 197-204, parent: platform/INTC1020:05, INTC1020:05:
  
  gpiochip3: GPIOs 205-284, parent: platform/INTC1020:04, INTC1020:04:
  
  gpiochip2: GPIOs 285-331, parent: platform/INTC1020:03, INTC1020:03:
  
  gpiochip1: GPIOs 332-444, parent: platform/INTC1020:01, INTC1020:01:
  
  gpiochip0: GPIOs 445-511, parent: platform/INTC1020:00, INTC1020:00:
  root@adlink-LEC-EL:/home/adlink# 

  

• To export the GPIO pin.

  echo N > export (N should replace with gpio chip base number)
  
  root@adlink-LEC-EL:/sys/class/gpio# echo 286 > export 
  root@adlink-LEC-EL:/sys/class/gpio# ls
  export  gpio286  gpiochip197  gpiochip205  gpiochip285  gpiochip332  gpiochip445  unexport
  root@adlink-LEC-EL:/sys/class/gpio# 

  

• To read the exported pin details, you can use the command cat.

  cd gpioN                   (N should replace with gpio chip base number)
  ls
  cat direction 
  cat value
  
  root@adlink-LEC-EL:/sys/class/gpio# cd gpio286
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# ls
  active_low  device  direction  edge  power  subsystem  uevent  value
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# cat direction 
  in
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# cat value
  0
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# 

  

• To read the direction and value of a pin.

  Direction:
  
  cat /sys/class/gpio/gpioN/direction  (N should replace with gpio chip base number)
  
  root@adlink-LEC-EL:/# cat /sys/class/gpio/gpio286/direction 
  in
  			or
  			
  cd /sys/class/gpio/gpioN
  cat direction 
   
  root@adlink-LEC-EL:/home/adlink# cd /sys/class/gpio/gpio286
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# cat direction 
  in
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# 
  
  Value:
  
  cat /sys/class/gpio/gpioN/value    (N should replace with gpio chip base number)
  
  root@adlink-LEC-EL:/# cat /sys/class/gpio/gpio286/value 
  0
  root@adlink-LEC-EL:/# 
  
   						or
  cd /sys/class/gpio/gpioN
  cat value 
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# cat value 
  0
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# 

• To write the direction of a pin to input.

  echo in > /sys/class/gpio/gpioN/direction  (N should replace with gpio chip base number)
  
  root@adlink-LEC-EL:/# echo in > /sys/class/gpio/gpio286/direction 
  root@adlink-LEC-EL:/# cat /sys/class/gpio/gpio286/direction 
  in
  root@adlink-LEC-EL:/#  
      
    						or 
    						
  cd /sys/class/gpio/gpioN
  echo in> direction 
  
  root@adlink-LEC-EL:/home/adlink# cd /sys/class/gpio/gpio286
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# echo in > direction 
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# cat direction 
  in
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# 

  

• To write the direction of a pin to output.

  echo out > /sys/class/gpio/gpioN/direction  (N should replace with gpio chip base number)
  
  root@adlink-LEC-EL:/# echo out > /sys/class/gpio/gpio286/direction  
  root@adlink-LEC-EL:/# cat /sys/class/gpio/gpio286/direction 
  out
  root@adlink-LEC-EL:/# 
   
      
    						or 
    						
  cd /sys/class/gpio/gpioN
  echo out> direction 
     
  root@adlink-LEC-EL:/home/adlink# cd /sys/class/gpio/gpio286
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# echo out > direction 
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# cat direction 
  out
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# 

• To write the value of a pin to a high.

  Note: Make sure the direction is out when trying to change the value to high or low.

  echo 1 > /sys/class/gpio/gpioN/value     (N should replace with gpio chip base number)
  
  
  root@adlink-LEC-EL:/# echo 1  > /sys/class/gpio/gpio286/value 
  root@adlink-LEC-EL:/# cat /sys/class/gpio/gpio286/value 
  1
  root@adlink-LEC-EL:/#                                                                               
  
  
  							or
  cd /sys/class/gpio/gpioN
  echo 1 > value
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# echo 1 > value 
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# cat value 
  1
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# 

  

• To write the value of a pin to a low.

  Note: Make sure the direction is out when you are trying to change the value to high or low.

  echo 0 > /sys/class/gpio/gpioN/value
  
  root@adlink-LEC-EL:/# echo 0  > /sys/class/gpio/gpio286/value 
  root@adlink-LEC-EL:/# cat /sys/class/gpio/gpio286/value 
  0
  root@adlink-LEC-EL:/# 
       
  
  						or
  						
  cd /sys/class/gpio/gpioN
  echo 0 > value
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# echo 0 > value 
  root@adlink-LEC-EL:/sys/class/gpio/gpio286# cat value 
  0
  root@adlink-LEC-EL:/sys/class/gpio/gpio286#

  

Access I2C GPIO Expander SX1509

The SX1509 I2C GPIO expander, connected to the ADLINK I2C bus, can be accessed exclusively through the ADLINK SEMA Utility.

ADLINK SEMA Utility Installation on Ubuntu

• It provides a set of functions to control GPIO pins.
• Only supports the specific external GPIO controller: SX1509 I/O expander on LEC-EL Module.

Please follow the steps below to install the SEMA-4.x EC Package in Ubuntu.

sudo apt install build-essential git hexer i2c-tools

sudo apt-get install uuid-dev

git clone https://github.com/ADLINK/sema-linux.git -b sema-ec
cd sema-linux

sudo make

sudo make install
sudo modprobe -a adl-ec adl-ec-boardinfo adl-ec-vm adl-ec-wdt adl-ec-hwmon adl-ec-nvmem adl-ec-bklight adl-ec-i2c adl-ec-gpio adl-ec-nvmem-sec

Note: You can verify the ADLINK SEMA Utility by using i2cdetect -l

i2cdetect -l

adlink@adlink-LEC-EL:~/sema-linux$ i2cdetect -l
i2c-3	unknown   	Synopsys DesignWare I2C adapter 	N/A
i2c-1	unknown   	SMBus I801 adapter at efa0      	N/A
i2c-6	unknown   	ADLINK BMC I2C adapter bus 2    	N/A
i2c-4	unknown   	Synopsys DesignWare I2C adapter 	N/A
i2c-2	unknown   	Synopsys DesignWare I2C adapter 	N/A
i2c-0	unknown   	SMBus CMI adapter cmi           	N/A
i2c-7	unknown   	ADLINK BMC I2C adapter bus 3    	N/A
i2c-5	unknown   	ADLINK BMC I2C adapter bus 1    	N/A
adlink@adlink-LEC-EL:~/sema-linux$ 

Accessing SX1509 GPIO Pins

For Ubuntu users on the EC controller, after installing the SX1509 kernel driver on their target device, they can use the GPIO sysfs Interface and SEMA GPIO EAPI function to access GPIO pins.

After loading the kernel driver, configure the SX1509 GPIO driver by executing the following command.

echo sx1509 0x3e > /sys/bus/i2c/devices/i2c-X/new_device    (X is the i2c bus SEMA(BMC) and SX1509 connected)

root@adlink-LEC-EL:/home/adlink/sema-linux# echo sx1509 0x3e > /sys/bus/i2c/devices/i2c-6/new_device
root@adlink-LEC-EL:/home/adlink/sema-linux# 

Note: Here, i2c-6 is used since SMBus is located at bus 6. 0x3e is the GPIO device slave address. Please refer to the screenshot below to find the i2c bus number and GPIO device address.

Using SEMA GPIO EAPI Function and GPIO sysfs Interface

To view the SEMA GPIO Commands

cd sema-linux
semautil /g

• To view the details of Gpiochip

  root@adlink-LEC-EL:/home/adlink/sema-linux# cat /sys/kernel/debug/gpio 
  gpiochip5: GPIOs 189-196, parent: platform/adl-ec-acpi, adl-ec-gpio:
  
  gpiochip4: GPIOs 197-204, parent: platform/INTC1020:05, INTC1020:05:
  
  gpiochip3: GPIOs 205-284, parent: platform/INTC1020:04, INTC1020:04:
  
  gpiochip2: GPIOs 285-331, parent: platform/INTC1020:03, INTC1020:03:
  
  gpiochip1: GPIOs 332-444, parent: platform/INTC1020:01, INTC1020:01:
  
  gpiochip0: GPIOs 445-511, parent: platform/INTC1020:00, INTC1020:00:
  root@adlink-LEC-EL:/home/adlink/sema-linux#

  Note: Here, gpiochip5(gpiochip189) was the loaded one.

  

• To export the GPIO pins in SX1509

  echo N > export (N should replace with gpio chip base number)
  
  root@adlink-LEC-EL:/sys/class/gpio# echo 189 > export 
  root@adlink-LEC-EL:/sys/class/gpio# ls
  export  gpio189  gpiochip189  gpiochip197  gpiochip205  gpiochip285  gpiochip332  gpiochip445  unexport
  root@adlink-LEC-EL:/sys/class/gpio# echo 190 > export 
  root@adlink-LEC-EL:/sys/class/gpio#

  

• To read the direction and value of a pin

  Using SEMA GPIO EAPI Function
  
  semautil /g get_direction [GPIO Bit]    
  semautil /g get_level     [GPIO Bit]
  
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g get_direction 7
  Direction : Input
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g get_level 7 
  Level: High
  root@adlink-LEC-EL:/home/adlink/sema-linux#
  
  
  Using GPIO sysfs Interface
  
  cat direction (or) cat /sys/class/gpio/gpioN/direction
  cat value (or)  cat /sys/class/gpio/gpioN/value
  
  
  root@adlink-LEC-EL:/sys/class/gpio/gpio189# cat direction 
  in
  root@adlink-LEC-EL:/sys/class/gpio/gpio189# cat value 
  0
  root@adlink-LEC-EL:/sys/class/gpio/gpio189#

• To write the direction of a pin to input or output

  Using SEMA GPIO EAPI Function
  
  semautil /g set_direction [GPIO Bit]                  [0 - Output or 1 - Input]
   
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g get_direction 7
  Direction : Output
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g set_direction 7 1
  Direction updated successfully
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g get_direction 7
  Direction : Input
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g set_direction 7 0
  Direction updated successfully
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g get_direction 7
  Direction : Output
  root@adlink-LEC-EL:/home/adlink/sema-linux#
  
  
  Using GPIO sysfs Interface
  
  echo in > /sys/class/gpio/gpioN/direction               (N should replace with gpio chip base number)
  echo out > /sys/class/gpio/gpioN/direction 
  
  root@adlink-LEC-EL:/home/adlink/sema-linux# echo in > /sys/class/gpio/gpio195/direction 
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g get_direction 7
  Direction : Input 
  root@adlink-LEC-EL:/home/adlink/sema-linux# echo out > /sys/class/gpio/gpio195/direction 
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g get_direction 7
  Direction : Output
  root@adlink-LEC-EL:/home/adlink/sema-linux# 

  

  Note: Can check the successful execution by command cat /sys/kernel/debug/gpio

  

• To write the value of a pin to low or high

  Note: Make sure the direction is out when you are trying to change the value to high or low.

  Using SEMA GPIO EAPI Function
  
  semautil /g set_level [GPIO Bit]                                  [0 - Low or 1 - High]
  
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g set_level 7 1
  GPIO Level updated successfully
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g get_level 7 
  Level: High
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g set_level 7 0
  GPIO Level updated successfully
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g get_level 7 
  Level: Low
  root@adlink-LEC-EL:/home/adlink/sema-linux# 
  
  
  Using GPIO sysfs Interface
  
  echo 1 > /sys/class/gpio/gpioN/value
  echo 0 > /sys/class/gpio/gpioN/value
  
  root@adlink-LEC-EL:/home/adlink/sema-linux# echo 0 > /sys/class/gpio/gpio195/value 
  root@adlink-LEC-EL:/home/adlink/sema-linux# 
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g get_level 7 
  Level: Low
  root@adlink-LEC-EL:/home/adlink/sema-linux# echo 1 > /sys/class/gpio/gpio195/value 
  root@adlink-LEC-EL:/home/adlink/sema-linux# semautil /g get_level 7 
  Level: High
  root@adlink-LEC-EL:/home/adlink/sema-linux#