PERIPLEX GPIO

This section explains how to interact with the GPIO's controller generated on Vaaman via Periplex.

How to Generate GPIO’s on the Vaaman ?

1. Create the json file:

   • To generate 5 GPIO controller, Your need to create a json file and copy the following content into it.

   Tip

   • how to create the json configuration file for periplex, You can check this Usage Guide

   {
      "uart": [],
      "i2c": [],
      "gpio": [
         {
               "id": 0,
               "GPIO-0": "GPIOT_RXP03",
               "GPIO-1": "GPIOT_RXN03",
               "GPIO-2": "GPIOT_RXP08",
               "GPIO-3": "GPIOT_RXN08",
               "GPIO-4": "GPIOT_RXN21",
               "GPIO-5": "GPIOT_RXP21",
               "GPIO-6": "GPIOT_RXP18",
               "GPIO-7": "GPIOT_RXN18"
         },
         {
               "id": 1,
               "GPIO-0": "GPIOT_RXP06",
               "GPIO-1": "GPIOT_RXN06",
               "GPIO-2": "GPIOT_RXN01",
               "GPIO-3": "GPIOT_RXP01",
               "GPIO-4": "GPIOT_RXP05",
               "GPIO-5": "GPIOT_RXN05",
               "GPIO-6": "GPIOT_RXN20",
               "GPIO-7": "GPIOT_RXP20"
         },
         {
               "id": 2,
               "GPIO-0": "GPIOT_RXP19",
               "GPIO-1": "GPIOT_RXN19",
               "GPIO-2": "GPIOT_RXP02",
               "GPIO-3": "GPIOT_RXN02",
               "GPIO-4": "GPIOT_RXP04",
               "GPIO-5": "GPIOT_RXN04",
               "GPIO-6": "GPIOT_RXP07",
               "GPIO-7": "GPIOT_RXN07"
         },
         {
               "id": 3,
               "GPIO-0": "GPIOT_RXP15",
               "GPIO-1": "GPIOT_RXN15",
               "GPIO-2": "GPIOT_RXP16",
               "GPIO-3": "GPIOT_RXN16",
               "GPIO-4": "GPIOT_RXP09",
               "GPIO-5": "GPIOT_RXN09",
               "GPIO-6": "GPIOT_RXN17",
               "GPIO-7": "GPIOT_RXP17"
         },
         {
               "id": 4,
               "GPIO-0": "GPIOT_RXP12",
               "GPIO-1": "GPIOT_RXN12",
               "GPIO-2": "GPIOT_RXP14",
               "GPIO-3": "GPIOT_RXN14",
               "GPIO-4": "GPIOT_RXP11",
               "GPIO-5": "GPIOT_RXN11",
               "GPIO-6": "GPIOT_RXN13",
               "GPIO-7": "GPIOT_RXP13"
         }
      ],
      "pwm": [],
      "ws": [],
      "spi": [],
      "onewire": [],
      "can": [],
      "i2s": []
   }
   

2. Run the periplex-sync command:

   • For example, if the JSON configuration for 5 GPIO controller is stored into the device.json file, the periplex-sync command would look like this:

   sudo periplex-sync -p device.json
   

   • After successfully running of periplex-sync command, it will ask for the reboot.

3. Reboot the board:

   • After rebooting, all configurations have been successfully applied.

   • You will get the 5-GPIO controller devices generated through Periplex like this:

      vicharak@vicharak:~$ ls /dev
      autofs           gpiochip9     media0        rtc        tty24  tty49     usbmon0      vcsu
      block            hdmi_hdcp1x   mem           rtc0       tty25  tty5      usbmon1      vcsu1
      btrfs-control    hugepages     mmcblk0       shm        tty26  tty50     usbmon2      vcsu2
      bus              hwrng         mmcblk0boot0  snd        tty27  tty51     usbmon3      vcsu3
      cec0             i2c-0         mmcblk0boot1  spidev0.0  tty28  tty52     usbmon4      vcsu4
      char             i2c-1         mmcblk0p1     stderr     tty29  tty53     usbmon5      vcsu5
      console          i2c-10        mmcblk0p2     stdin      tty3   tty54     usbmon6      vcsu6
      cpu_dma_latency  i2c-4         mmcblk0p3     stdout     tty30  tty55     v4l          vcsu7
      crypto           i2c-7         mmcblk0p4     sw_sync    tty31  tty56     v4l-subdev0  vendor_storage
      disk             i2c-9         mmcblk0p5     tty        tty32  tty57     v4l-subdev1  vhci
      dma_heap         iep           mmcblk0p6     tty0       tty33  tty58     v4l-subdev2  video0
      dri              iio:device0   mmcblk0p7     tty1       tty34  tty59     vcs          video1
      drm_dp_aux0      initctl       mmcblk0p8     tty10      tty35  tty6      vcs1         video2
      fb0              input         mmcblk0rpmb   tty11      tty36  tty60     vcs2         video3
      fd               kmsg          mpp_service   tty12      tty37  tty61     vcs3         video4
      full             log           mqueue        tty13      tty38  tty62     vcs4         video-dec0
      fuse             loop0         net           tty14      tty39  tty63     vcs5         video-enc0
      gpiochip0        loop1         null          tty15      tty4   tty7      vcs6         watchdog
      gpiochip1        loop2         periplex      tty16      tty40  tty8      vcs7         watchdog0
      gpiochip10       loop3         port          tty17      tty41  tty9      vcsa         zero
      gpiochip2        loop4         ptmx          tty18      tty42  ttyFIQ0   vcsa1        zram0
      gpiochip3        loop5         pts           tty19      tty43  ttyS0     vcsa2
      gpiochip4        loop6         ram0          tty2       tty44  ubi_ctrl  vcsa3
      gpiochip5        loop7         random        tty20      tty45  uhid      vcsa4
      gpiochip6        loop-control  rfkill        tty21      tty46  uinput    vcsa5
      gpiochip7        mali0         rga           tty22      tty47  urandom   vcsa6
      gpiochip8        mapper        rk_cec        tty23      tty48  usb-ffs   vcsa7
   

How to interact with the generated GPIO’s ?

The Periplex platform dynamically exposes GPIO controllers as gpiochip devices, which can be accessed via paths like:

/dev/gpiochip6
/dev/gpiochip7
/dev/gpiochip8
...

These gpiochip devices allow users to control individual GPIO pins, enabling interaction with external hardware components such as LEDs, sensors, and buttons.

Simple set/get GPIO’s pin values

To use the gpioset and gpioget commands, you need to install the libgpiod package. These tools are part of the libgpiod-utils package, which provides user-space tools for interacting with GPIO lines via the Linux GPIO character device interface.

sudo apt install libgpiod-utils

Each gpiochip represents a bank of GPIO pins. For example, gpiochip6 contains pins 1 to 8.

1. Identify the GPIO Pin:

   • You can list available GPIO lines using:

   gpioinfo
   

2. Setting GPIO Pin Values:

   • To set a GPIO pin value (HIGH or LOW), use the following command:

   gpioset gpiochip6 <pin_number>=<value>
   

   • <pin_number>: The pin number (1 to 8).

   • <value>:

     • 1 — Set pin HIGH (active)

     • 0 — Set pin LOW (inactive)

   • For example, Set pin 1 to LOW:

   gpioset gpiochip6 1=0
   

   • For example, Set pin 3 to HIGH:

   gpioset gpiochip6 3=1
   

   • For example, Set multiple pins at once:

   gpioset gpiochip6 2=1 4=0
   

3. Reading GPIO Pin Values

   • To check the current value of a GPIO pin, use:

   gpioget gpiochip6 <pin_number>
   

   • For example, Get the value of pin 5:

   gpioget gpiochip6 5
   

   • It will output either 0 (LOW) or 1 (HIGH).

Note

• Ensure you have the correct permissions to access GPIOs. You may need to run these commands with sudo.

• The gpiochip6 represents the GPIO controller, and the pin numbers (1 to 8) correspond to the GPIO lines.

Example of using the GPIO protocol

This example demonstrates controlling an LED using the GPIO protocol.

• Setting the GPIO pin high will turn on the LED.

• Setting the GPIO pin low will turn off the LED.

Means high signal on the GPIO pin activates the connected device and low signal on the GPIO pin deactivates the connected device.