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GPIO ARE DEMO.md

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General Purpose Input Output (GPIO) in the Application Runtime Environment (ARE) Demo

Requirements

  • IMX8ULP-EVK
  • Azure Sphere NRE Image for IMX8ULP
  • Mariner ARE Image for IMX8ULP

Software Setup

  1. Flash the NRE image to the IMX8ULP.Azure Sphere documentation for deployin to imx8ulp
  2. Copy the ARE image using Azure Sphere documentation forsync-are-to-device
  3. Connect to the NRE through SSH.
  4. Devices come up with unique hostnames in the form azsphere-XXXXXXXX.local. Names are reset each time the device is reflashed but stay the same between reboots. To find your devices name you have two options:

4.1.Connect to the serial console. You should see the hostname on the login prompt, like this:

Azure Sphere V2 NRE 2209 azsphere-cf5ab0a1ff83a841 ttyAMA0

azsphere-cf5ab0a1ff83a841 login:

4.2.Use avahi-browse to discover the device (this command is run on the Dev PC):

avahi-browse -at

+ virbr0 IPv4 azsphere-a5317e1508791b21                     SSH Remote Terminal  local
  1. Connect to the ARE through SSH. (e.g. ssh -J [email protected] [email protected])
  2. use password when prompted

Demo 1: GPIO Device sysfs access

Goal

Demonstrate the use of arectl to enable GPIO pins peripheral passthrough to the ARE.

Steps

  1. Connect to the NRE through SSH.
  2. Enable GPIO passthrough:
#GPIOF PIN 20 controls GREEN LED
#GPIOF PIN 29 controls RED   LED

sudo arectl peripherals enable GPIOF PTF20=on PTF29=on

  1. Reboot the device for the overlays to be applied: sudo reboot now

  2. Check GPIOF settigns

arectl peripherals details GPIOF

Name:                GPIOF
Description:         GPIO instance F in the Application Domain
Used Resources:     
                     GPIOF
Data Files:         
                     /boot/0001-GPIOF-nre.dtbo
                     /run/images/active_are/0001-GPIOF-are.dtbo
Options:            
               ...
               PTF20 on
               PTF29 on
               ...
  1. We can check from ARE terminal the current state of GPIO settings in the system
cat /sys/kernel/debug/gpio

#From the output we detect the GPIO Base for GPIOF 

gpiochip0: GPIOs 480-511, parent: platform/2d010080.gpio, 2d010080.gpio:
  1. enabling GPIOs 20/29 in sysfs
#Each GPIO must be individually activated.
#base 480 + 20 for GREEN LED base
echo 500 > /sys/class/gpio/export

#base 480 + 29 for RED   LED base
echo 509 > /sys/class/gpio/export

#GPIO set as output 480 + 20 for GREEN LED base
echo out > /sys/class/gpio/gpio500/direction

#GPIO set as output 480 + 29 for RED   LED base
echo out > /sys/class/gpio/gpio509/direction

#Turn ON GPIO 20 (GREEN LED)
echo 1 > /sys/class/gpio/gpio500/value     

#Turn 0FF GPIO 20
echo 0 > /sys/class/gpio/gpio500/value

#Turn ON GPIO 29 (RED LED)
echo 1 > /sys/class/gpio/gpio509/value     

#Turn 0FF GPIO 29 
echo 0 > /sys/class/gpio/gpio509/value

MicrosoftTeams-image (1)

Demo 2: Simple GPIOF-EVK-LEDs Interphase

Goal

Demonstrate the use of arectl to enable GPIOF-EVK-LEDs peripheral passthrough to the ARE.

Steps

  1. Connect to the NRE through SSH.
  2. Enable GPIOF-EVK-LEDs passthrough:
#GPIOF-EVK-LEDs controls
sudo arectl peripherals enable GPIOF
sudo arectl peripherals enable GPIOF-EVK-LEDs

  1. Reboot the device for the overlays to be applied: sudo reboot now

  2. Check GPIOF settigns

sudo arectl peripherals enable GPIOF-EVK-LEDs

Enabled peripherals:

                GPIOF: GPIO instance F in the Application Domain
       GPIOF-EVK-LEDs: EVK LEDs attached to GPIOF
  1. We can check from ARE terminal the current state of GPIO settings in the system
cat /sys/kernel/debug/gpio

#From the output we detect the GPIO Base for GPIOF 

gpiochip0: GPIOs 480-511, parent: platform/2d010080.gpio, 2d010080.gpio:
 gpio-500 (                    |green:user          ) out lo 
 gpio-509 (                    |red:user            ) out lo
  1. enabling GPIOF-EVK-LEDs
#Turn ON GPIO 20 (GREEN LED)
echo 1 > /sys/class/leds/green\:user/brightness 

#Turn ON GPIO 29 (RED LED)
echo 1 > /sys/class/leds/red\:user/brightness

#Turn 0FF GPIO 20

Demo 3: Control GPIOs in Linux with a C application

Demonstrate the use of GPIO Controls in linux with C application in the ARE using chardev.

Steps

  1. Connect to the NRE through SSH.
  2. Enable GPIO passthrough:
#GPIOF PIN 20 controls GREEN LED
#GPIOF PIN 29 controls RED   LED

sudo arectl peripherals enable GPIOF PTF20=on PTF29=on

  1. Reboot the device for the overlays to be applied: sudo reboot now

  2. Add required firewall rules. Run in the NRE:

sudo bash -c "cat > /etc/asfirewalld/are_development.asfirewalld.json" << 'EOF'
{
    "Environment": "are",
    "FirewallRules": [
        {
            "User": "*",
            "AllowedOutgoing": [
                "packages.microsoft.com"
            ],
            "Comment": "Mariner (t)dnf Repos"
        },
        {
            "User": "*",
            "AllowedOutgoing": [
                "pypi.python.org",
                "pypi.org",
                "pythonhosted.org",
                "files.pythonhosted.org"
            ],
            "Comment": "Python Pip Repos"
        },
        {
            "User": "*",
            "AllowedOutgoing": [
                "githubusercontent.com",
                "gist.githubusercontent.com",
                "raw.githubusercontent.com"
            ],
            "Comment": "GitHub Gist"
        }
    ]
}
EOF

  1. Enabled the new rules by reloading the firewall: sudo asfirewallctl appconfig reload

  2. Connect to the ARE through SSH. (e.g. ssh -J [email protected] [email protected])

  3. Download software requirements in the ARE:

  4. Search the list of packages and install build-essential package to get gcc compiler

 tdnf list
 tdnf search build
 tdnf install build-essential
 gcc --version
  1. install VIM editor
 tdnf install vim
  1. Check for the presence of Linux kernel GPIO user space interface
 ls /dev/gpiochip0
  1. Create and compile a simple program to test the GPIO interface

11.1 Create a C file for example GpioCtrl.c

 > GpioCtrl.c

11.2 Edit the C file you can use this code as a simple example to experiment:

 vim GpioCtrl.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/gpio.h>

int main () {
   // 
   // variable declarations
   //
   int                       gpioFile;
   struct gpiohandle_data    gpioData;
   struct gpiohandle_request redLed;
   struct gpiohandle_request greenLed;

   // 
   // Open gpiochip device file 
   //
   gpioFile = open ("/dev/gpiochip0", O_RDWR);
   
   if (gpioFile < 0) {
     perror("ERROR: unable to open gpiochip0");
     return -1;
   }

   // 
   // Green LED configuration (GPIOF-20)
   //
   greenLed.flags = GPIOHANDLE_REQUEST_OUTPUT;
   strncpy(greenLed.consumer_label, "GREEN LED", GPIO_MAX_NAME_SIZE);
   memset(greenLed.default_values, 0, sizeof(greenLed.default_values));

   // GPIOF pin 20 needs 1 GPIO line                                  
   greenLed.lines            = 1;    
   greenLed.lineoffsets[0]   = 20;  

   // 
   // Red LED configuration  (GPIOF-29)
   //
   redLed.flags = GPIOHANDLE_REQUEST_OUTPUT;
   strncpy(redLed.consumer_label, "RED LED", GPIO_MAX_NAME_SIZE);
   memset(redLed.default_values, 0, sizeof(redLed.default_values));

   // GPIOF pin 29 needs 1 GPIO line                       
   redLed.lines            = 1;
   redLed.lineoffsets[0]   = 29;   

   //
   // program GPIOF 20 to control Green LED
   //
   if (ioctl(gpioFile, GPIO_GET_LINEHANDLE_IOCTL, &greenLed) < 0) {
     perror("ERROR: unable to control Green LED - GPIOF 20");
     close(gpioFile);
     return -1;
   }
   
   //
   // program GPIOF 29 to control Red LED
   //
   if (ioctl(gpioFile, GPIO_GET_LINEHANDLE_IOCTL, &redLed) < 0) {
     perror("ERROR: unable to control RED LED - GPIOF 29");
     close(gpioFile);
     close(greenLed.fd); // close green led file handler
     return -1;
   }

   //
   // set Green LED
   //
   gpioData.values[0] = 1;
   if (ioctl(greenLed.fd, GPIOHANDLE_SET_LINE_VALUES_IOCTL, &gpioData) < 0) {
     perror ("ERROR: unable to set GREEN LED - GPIOF 20");
   }

   // insert 2s wait to see the result of the led action
   sleep (2);

   //
   // clear Green LED
   //
   gpioData.values[0] = 0;
   if (ioctl(greenLed.fd, GPIOHANDLE_SET_LINE_VALUES_IOCTL, &gpioData) < 0) {
     perror ("ERROR: unable to set GREEN LED - GPIOF 20");
   }

   // insert 2s wait to see the result of the led action
   sleep (2);

   //
   // set Red LED
   //
   gpioData.values[0] = 1;
   if (ioctl(redLed.fd, GPIOHANDLE_SET_LINE_VALUES_IOCTL, &gpioData) < 0) {
     perror ("ERROR: unable to set RED LED - GPIOF 29");
   }

   // insert 2s wait to see the result of the led action
   sleep (2);

   //
   // clear Red LED
   //
   gpioData.values[0] = 0;
   if (ioctl(redLed.fd, GPIOHANDLE_SET_LINE_VALUES_IOCTL, &gpioData) < 0) {
     perror ("ERROR: unable to set RED LED - GPIOF 29");
   }
 
   //                                                                         
   // close device file handles
   //
   close(gpioFile);
   close(redLed.fd);
   close(greenLed.fd);

   // exit program
   return 0;
}

11.3 Compile & execute the application:

 gcc GpioCtrl.c -o GpioCtrl
 ./GpioCtrl

(WIP)