TRB141 1-Wire Setup/Configuration

The information on this page is updated in accordance with 00.07.04 firmware version.

Introduction

Inputs and outputs are used for monitoring and controlling a connected device or receiving signals from that device in order to trigger certain events.

1-Wire is a voltage-based digital system that works with two contacts, data and ground, for half-duplex bidirectional communication. Compared to other serial communication systems such as I2C or SPI, 1-Wire devices are designed for use in a momentary contact environment. It is developed by Dallas Semiconductor (now Maxim Integrated) that allows devices to communicate over a single wire using a complex protocol to transfer data. The 1-Wire protocol is commonly used for low-speed communication between microcontrollers and their peripherals, such as temperature sensors, memory devices, and other digital and analog sensors.

Currently, only one Teltonika device (TRB141) supports 1-Wire communication protocol.

In this chapter, we will set up and configure the 1-Wire sensor with TRB141.

Prerequisites

• TRB141
• 1-Wire sensor
• If 1-Wire doesn't have its Wires(Like Dallas DS1820 used in this example) you will need additional wires to connect the sensor to TRB141

Connecting 1-Wire Sensor with TRB141

First of all we will connect the 1-Wire sensor with TRB141, for this example, we will be using two different 1-Wire sensors Dallas DS1820 and Dallas DS9092. Before we proceed with the connection, make sure you know how your 1-Wire sensor has to be connected, or open your 1-Wire sensor data sheet to reference where each wire should be connected.

DS1820 connection

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The wiring for DS1820 can be seen in the picture provided below. We will connect the 1st wire to TRB141, the second wire to the 1-Wire pin on TRB141, and the 3rd wire to the + pin. Please see the Wiring of DS1820 and Pinout of TRB141 on which pins should be connected.

Wiring

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Pinout

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• 1 - Red Wire
• 2 - White Wire
• 3 - Green Wire

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DS9092 connection

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Note: Keep in mind that the wire colors of your Ibutton can be different to ones used for this example.

The wiring for DS9092 can be seen in the picture provided below. We will connect the Green Wire to TRB141 1-Wire Pin, the Red Wire to the Ground pin on TRB141. Please see the Wiring of DS9092 and Pinout of TRB141 on which pins should be connected.

Wiring

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Pinout

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• 1 - Green Wire
• 2 - Red Wire

Picture-example

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1-Wire configuration on TRB141

1-Wire configuration is simple, you will only need to log in to your device's CLI/SSH and execute a few commands.

Firstly, let's connect to your device's CLI. Open your WebUI by opening Browser on your computer and inputting your device's IP(by default 192.168.2.1). Now navigate to System → CLI. Login with your root username and your admin password:

1-Wire activation commands

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In order to read one-wire sensor data you will need to follow these steps:

1. Set one-wire sensor value to "1' using the ubus command:

   ubus call ioman.gpio.onewire update '{"value":"1"}'

2. List the connected one-wire devices from the /sys/bus/w1/devices directory using the ls command:

   ls /sys/bus/w1/devices

3. Choose a sensor to read and obtain its state from the /sys/bus/w1/devices/<device_name>/w1_slave directory:

   cat /sys/bus/w1/devices/<device_name>/w1_slave

Commands executed on CLI:

Testing the configuration

The configuration testing is straight forward, you will need to execute command cat /sys/bus/w1/devices/<device_name>/w1_slave you should see the data from your sensor in the CLI output, keep in mind that the output entirely depends on the 1-Wire sensor used, so most likely you will see different outup. And if you will be using a similar 1-Wire device to DS9092 you will need to touch and hold the key for a few seconds until you would see the slave device.

The example output:

Connecting Multiple 1-Wire Sensors with TRB141

The configuration for connecting multiple 1-wire sensors is the same as above. There’s no restriction or limit on the number of sensors that can be connected to TRB141. However, there’s a limit on how many sensors can be read every second which is up to 75 sensors only.

DS18B20 connection

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The wiring image is a similar scheme that we used as our guide for connecting multiple 1-Wire sensors on the TRB141.

Wiring

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Picture-example

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Output

Enable the 'ioman.gpio.onewire' service. You can configure this by following the instructions above regarding 1-Wire activation commands.

We should be able to see all the 1-wire sensor directories and read their values accordingly.

28-00000e55f136 = 31.1 °C

28-00000e7dfff9 = 24.3 °C

Summary

In this article we connected and configurated different 1-Wire sensors and learned how to configure the 1-Wire sensor to display data on TRB141 SSH/CLI. Additionally, in this article you can find how different 1-Wire sensors have to be wired/connected to TRB141.

References

TRB141 Input/Output