Temperature Sensor Example Application

Table of Contents

• Introduction
• Hardware Prerequisites
• Software Prerequisites
• Functional Description
• Software Overview
  • Application Files
  • Example Application
• Usage
• Buttons
• Display
• Setting up the Thread Network
• Interfacing with the Example Application

Introduction

This document discusses how to use the Temperature Sensor Example Application and the different parts that compose it. Thermostat Example Application is a standalone CoAP server example running on Thread.

Some of the areas explored are:

• Setting up a network.

• Bringing up the device as a Minimum Thread Device (MTD).

• Initialization and use of the Constrained Application Protocol (CoAP) APIs.

Hardware Prerequisites

Device Reporting example

• 3 x CC2652 LaunchPads

• 1 x BeagleBone Black.

• (optional) 1 x Sharp96 LCD boosterpack.

Basic CoAP usage

• 2 x CC2652 LaunchPads

• (optional) 1 x Sharp96 LCD boosterpack.

Software Prerequisites

• Code Composer Studio(CCS) v7.3 or higher

Functional Description

Software Overview

This section describes software components and the corresponding source file.

Application Files

• tempsensor.[ch]: Contains the application’s event loop, CoAP callback functions, device initialization function calls, and all temperature sensor specific logic.

• otstack.[ch]: OpenThread stack processing, instantiation and network parameters.

• task_config.h: This file contains the definitions of the RTOS task priorities and stack sizes.

If the application is compiled with the predefined symbol, ALLOW_PRECOMMISSIONED_NETWORK_JOIN, following parameter should be verified in otstack.h.

• OT_NWK_PAN_ID This is the Personal Area Network (PAN) identifier of the network. The default value is set to 0xface. Please make sure this matches the PAN ID set in the border router, otherwise change it accordingly.

• OT_NWK_CHANNEL This sets the channel on which the device will be operating in the 2.4 GHz spectrum as per the IEEE 802.15.4 specification. The default value is channel 14.

Example Application

This application provides an example implementation of a temperature sensor using the Thread wireless protocol and CoAP as the application layer protocol. The temperature sensor application is configured as a minimum thread Device (MTD) which supports CoAP commands to read the temperature. The temperature sensor example also includes basic reporting functionality to a known IPv6 address, in this case the thermostat example application.

Usage

This section describes how to set up and run the Temperature Sensor Example Application.

Buttons

• BTN-1 + BTN-2 at boot: A factory reset of the non-volatile storage is performed. This must be pressed at the start of the OtStack_task function.

• BTN-2: Start the joining process. This may be pressed after the hold image appears on-screen.

Display

The temperature sensor events will be displayed through UART to a serial terminal emulator. To enable the serial terminal in CCS press ctrl + shift + alt + T, select Serial Terminal under Choose terminal, select 115200 for Baud Rate and click OK

Setting up the Thread Network

Basic CoAP usage

This section describes how to set up a Thread network. The application supports the ability to be commissioned into a Thread network. Commissioning may be bypassed by compiling with the ALLOW_PRECOMMISSIONED_NETWORK_JOIN predefined symbol.

1. Set up a LaunchPad as a CLI FTD device by following the READMEs files in the respective application folder.

2. Load and run the Temperature Sensor example on a second LaunchPad.

3. The Temperature Sensor will print out the device’s EUI64 and the application’s PSKd (pre-shared key device identifier) over the UART terminal. If the device was already commissioned or was built with the ALLOW_PRECOMMISSIONED_NETWORK_JOIN symbol, commissioning will not be necessary, skip to step 8.

pskd: TMPSENS1 EUI64: 0x00124b000f6e6113

1. Start a commissioner on the CLI FTD by issuing the following command. commissioner start It will display Done if it is successful in starting the network.

2. Add Temperature Sensor LaunchPad device as a joiner device by providing the EUI64 and pskd as credentials to the commissioner. commissioner joiner add 00124b000f6e6113 TMPSENS1 It will display Done if it is successful in adding the joiner entry.

3. Now on the Temperature Sensor LaunchPad, press BTN-2 to start the joining process. The UART will print Joining Nwk ....

4. Once the joining process has successfully completed, the UART will print Joined Nwk. The green LED should turn on on the shade LaunchPad once it has joined the network.

5. Next we need to get the IPv6 address of the temperature sensor LaunchPad. Use the command ping ff03::1 to send an ICMP echo request to the realm-local all nodes multicast address. All devices on Thread network will respond with an ICMP echo response. You will see in the terminal a response like the one below.

8 bytes from fd00:db7:0:0:0:ff:fe00:b401: icmp_seq=1 hlim=64 time=11ms

Running the example with reporting

The Temperature Sensor example has a basic reporting feature. When connected to a network with a Globally Unique Address, the temperature sensor will attempt to post the temperature it reads to the thermostat. To enable this feature you need to setup a Thread network with an NCP connected to a BeagleBone Black and a LaunchPad with the Thermostat Example. Consult the NCP example’s README for information on setting up a BeagleBone Black based border router.

NOTE: This kind of static addressing is a hack of SLAAC. Proper discovery mechanisms are being explored.

Interfacing with the Temperature Sensor Example Application

The temperature sensor application hosts a simple CoAP server with one registered resource for the current temperature. This resource supports CoAP GET commands. Any device with scope of the temperature sensor’s IPv6 address can send commands to the temperature sensor application.

Temperature Sensor Attribute URI:

• Temperature value: tempsensor/temperature

Open up the serial terminal to the cli_ftd application and also to the temperature sensor application.

Starting the CoAP client

In the CLI FTD serial terminal, type coap start at the prompt to start the CoAP service. It will display the following message if it successful in starting the CoAP service. Coap service started: Done

Getting status from the Temperature Sensor

To get the temperature sensor’s current temperature, type the following command into the CLI FTD terminal.

coap get fd00:db7:0:0:0:ff:fe00:b401 tempsensor/temperature

NOTE: The IPv6 address will be different for your setup

The temperature sensor should respond, and the cli_ftd will print a message like the following.

Received coap response with payload: 3635

Converting the payload from hex to ascii we get 65 which is the temperature in degrees Fahrenheit.