PERIPLEX ONE-WIRE

This section explains how to interact with the ONE-WIRE peripherals generated on Vaaman via Periplex.

How to Generate ONE-WIREs on Vaaman ?

  1. Create the json file:

    • To generate 2 ONE-WIRE peripherals, you 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": [],
   "i2cmaster": [],
   "gpio": [],
   "pwm": [],
   "ws": [],
   "spi": [],
   "onewire": [
      {
         "id": 0,
         "ONEWIRE": "GPIOT_RXP28"
      },
      {
         "id": 1,
         "ONEWIRE": "GPIOL_73"
      },
   ],
   "can": [],
   "i2s": [],
   "i2cslave": [],
   "jtag": [],
   "dht": []
}

  2. Run the periplex-sync command:

    • For example, if the JSON configuration for 2 ONE-WIRE 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 the system, the two ONE-WIRE peripherals will be automatically initialized on Vaaman.

         vicharak@vicharak:/sys/bus/w1/devices$ ls
   14-000009904f27  28-0ee9d4443c4a  w1_bus_master1  w1_bus_master2

    • For example, if two ONE-WIRE peripherals are connected — a temperature sensor (DS18B20) on GPIOT_RXP28 and an EEPROM (DS2430A) on GPIOL_73 — you can access them through the following device files:

    • Temperature Sensor (DS18B20) : /sys/bus/w1/devices/28-0ee9d4443c4a

    • EEPROM (DS2430A) : /sys/bus/w1/devices/14-000009904f27

    Note

    • The device file names may vary depending on the specific devices connected and their unique IDs.

    • Ensure that the required ONE-WIRE kernel modules are properly loaded to enable device detection. For example, the w1-gpio and w1_therm modules are typically required for temperature sensors, while the w1_ds2430 module is needed for the DS2430A EEPROM.

    • If the /sys/bus/w1/devices/ directory appears empty, verify the hardware connections and ensure that the ONE-WIRE devices are correctly connected to the specified GPIO pins.

    • You can read data from these device files using standard Linux commands such as cat, or by writing custom scripts to interact with the devices programmatically.

How to interact with generated ONE-WIREs ?

The Periplex platform dynamically generates ONE-WIRE devices, which are accessible through device nodes such as:
/sys/bus/w1/devices/XX-XXXXXXXXXXXX

  • Where XX-XXXXXXXXXXXX represents the unique identifier for each ONE-WIRE device connected to the bus.

  • For example, a DS18B20 temperature sensor might appear as 28-0ee9d4443c4a, while a DS2430A EEPROM device could show up as 14-000009904f27.

  • These device nodes can be used to read data from or write data to the connected ONE-WIRE devices, depending on their functionality.

Using cat command / shell scripts

  1. Using the cat command:

    • To read temperature data from a DS18B20 temperature sensor, you can use the following command:

    cat /sys/bus/w1/devices/28-0ee9d4443c4a/temperature

  2. Using shell scripts:

    • Using shell scripts interact with the devices programmatically is also possible.Here is a simple example of a shell script that firstly writes data to a DS2430A EEPROM device and then reads it back to verify the operation:

    #!/bin/bash

# Navigate to your device
cd /sys/bus/w1/devices/14-000009904f27

# Test with simple data
TEST_DATA="12345678"

echo "=== EEPROM Write and Verify Test ==="
echo "Device: $(pwd)"
echo "Test data: '$TEST_DATA'"
echo

# Check if eeprom file exists
if [ ! -f "eeprom" ]; then
   echo "ERROR: eeprom file not found in $(pwd)"
   exit 1
fi

# Write data to EEPROM
echo "Writing data to EEPROM..."
sudo bash -c "echo -n '$TEST_DATA' > eeprom"

if [ $? -eq 0 ]; then
   echo "✓ Written: '$TEST_DATA'"
else
   echo "✗ Failed to write data to EEPROM"
   exit 1
fi

# Small delay to ensure write is complete
sleep 1

# Read data back from EEPROM
echo "Reading data from EEPROM..."
READ_DATA=$(sudo cat eeprom | tr -d '\0' | head -c ${#TEST_DATA})

echo "✓ Read: '$READ_DATA'"
echo

# Compare written and read data
if [ "$TEST_DATA" = "$READ_DATA" ]; then
   echo "✓ SUCCESS: Data verification passed!"
   echo "  Written: '$TEST_DATA'"
   echo "  Read:    '$READ_DATA'"
else
   echo "✗ FAILURE: Data verification failed!"
   echo "  Expected: '$TEST_DATA'"
   echo "  Got:      '$READ_DATA'"
   echo "  Length expected: ${#TEST_DATA}"
   echo "  Length got:      ${#READ_DATA}"

   # Show hex dump for debugging
   echo
   echo "Hex dump of first 16 bytes from EEPROM:"
   sudo xxd -l 16 eeprom
fi

echo
echo "Test completed."

Tip