Power consumption of autonomous IoT devices

Evaluation of the power consumption of an autonomous IoT device

The popular Arduino Uno micro-controller  in combination with GSM/GPRS shields based on the SIM900 chip are quite popular as prototype platform for new developments or autonomous IoT systems. The main challenge to implement a true energy autonomous system is the considerable energy demand of this components if you use them out-of the-box. Data sheets and other supplier information give no or only limited information of the true power requirements.

An evaluation project from CADEMIS determined the energy requirements of a basic setup which might be a useful  indication for the design of related IoT systems.

 

System Setup:

In order to determine the energy consumption a simple system setup was used to determine the current at a 12 Volt battery.

Wiring Schema

A control program  implemented in the Arduino IDE  switches between four different states:

1: GSM board OFF, Onboard LED ON

2: GSM board OFF, Onboard LED OFF

3: GSM board ON, Onboard LED OFF

4: GSM board ON, Onboard LED ON

Between the states a delay of 10 seconds was implemented in order to get a steady reading on the Ampere-meter.

Components:

Arduino Source Code:

The source code for Arduino IDE 1.6.13 to switch between the four states mentioned above:

Source Code Power Consumption Evaluation

Measurement Results:

GSM Shield LED Current / mA Power / mW
OFF ON 54 mA 648 mW
OFF OFF 44 mA 528 mW
ON OFF 68 mA 816 mW
ON ON 80 mA 960 mW

Special remark on switching on the GSM Shield: When switching on the board (between state 2 and 3) the power consumption is between 70 mA and 220 mA for about 5 seconds. As mentioned in several posts in forums causes every switching operation a significant peak in current and power.

Summary:

It is strongly recommended to switch off unused loads in order to reduce the power consumption by up almost 50% for a simple setup like this. This can double the operation-time between battery reloading or reduce the solar power requirements and costs.

References:

  • Thanks to the girls and guys from Geeetech for publishing the basic information on how to control the SIM900 board:

http://www.geeetech.com/wiki/index.php/Arduino_GPRS_Shield

Cademis Weather Monitor

CWM System OverviewCademis Weather Monitor is an environmental monitoring system which allows global access to sensor information from in and around your home.

Based on established communicaiton standards and with our Open Access policy it will enable everyone to build a solution step by step.

Follow these pages to get up and running  or let us know if you need a specific solution (special sensors, special data management, smart data analys, actuator interface) and we will try to help.

Coming up soon – The Cademis Weather Monitor!

We are excited to announce the upcoming release of the Cademis Weather Monitor. The original prototype was published  two years ago at Instructables. After several design iterations it will be released as Open Source Solution on 1. January  2016.

CWM R3
Cademis Weather Monitor Gateway

Main Features

  • Appealing design and simple to use gateway unit
  • Fits perfectly in any living room or kitchen
  • Connects to any enviromental sensor wireless via 868 MHz or direct via I2C
  • Easy Monitoring and Analytics over the Web
  • Open Source Electronic Design, MCAD, Firmware and Software

Over the coming weeks we will publish all design and manufacturing instructions which will allow you to build the Cademis Weather Monitor.

Arduino Yún Essentials

The Arduino Yún is the frist true IoT board from Arduino which gives you a real-time controller combined with a Linux environment with almost unlimited connection possibilities (Ethernet, WiFi, USB)

It is the best tool to monitor and control your devices, and here you find a few instructions to get you up and running.

Arduinio Yun
Arduinio Yun

Upgrade to latest Linux (optional)

If you are not sure if you have the latest Linux version on your Yun you will need to upgrade. To upgrade or reinstall the OpenWrt-Yun image on your Yún, you’ll need to download the zip file from the download page. Once you’ve unpacked the file, move the binary image file to the root folder of a microSD card and insert the card into the Yún.

The recommended way is to upgrade through the Web Panel. Find the step-by-step instruction here: https://www.arduino.cc/en/Tutorial/YunSysupgrade

Next step is to connect the Arduino Yun to your wireless network:

Connect to your WIFI NEtwork (WLAN)

After WLAN reset and when you first power on the Yún, it will create a WiFi network called ArduinoYun-XXXXXXXXXXXX. Connect your computer to this network!

Once you have obtained an IP address, open a web browser, and enter http://arduino.local or 192.168.240.1 in the address bar. After a few moments, a web page will appear asking for a password. Enter “arduino” and click the Log In button.

 

You will find a page with some diagnostic information about the current network connections. The first is your WiFi interface, the second is your ethernet connection. Press the Configuration button to proceed.

On the new page, you will configure your Yún, giving it a unique name and identifying what network you want to connect to.

In the Yún NAME field, give your Arduino a unique name. This is important if you plan to use more than one Yun on your network in the future. So if you name it yun123 you will need to connect to http://yun123.local the next time to want to configure the wifi settings.

Choose a password of 8 or more characters for your Arduino. If you leave this field blank, the system retains the default password of arduino

If you wish, you can set the timezone and country. It is recommended to set these options as it may help connecting to local WiFi networks. Setting the local timezone also selects the country’s regulatory domain.

Enter the name of the WiFi network you wish to connect to.

Select the security type, and enter the password.

When you press the Configure & Restart button, the Arduino will reset itself and join the specified network. The Arduino network will shut down after a few moments.

You can now join the network you assigned to the Yún.