New version v2.0 released

We are excited to announce the new improved version of oZm v2.0. In this new version, major enhancements have been made to most of the basic modules, resulting in a much more stable and improved system.

Operating system

The first major change has been to switch the operating system from Debian to OpenWRT. This change has been motivated by the improved management of the WiFi module as well as the greater stability in the connection allowed by OpenWRT. Now, oZm takes up much less disk space and the necessary packages are better managed. In previous versions, we have had a lot of problems with the NetworkManager that ships with Debian, which caused a lot of disconnections and crashes. Also, we have found that many modern routers do not adequately support certain Linux systems and this means that the web is not accessible under certain circumstances.

Web redesign

The website has been completely redesigned. It is now more intuitive and better organized. Additional information regarding system properties (RAM, signal strength or temperature) has been added. In addition, some views have been reorganized and new ones have been added.

New Tariff module

One of the important achievements has been the creation of the tariff module. Thanks to this module it is now possible to get the cost of the consumed energy in real time according to the electricity tariff defined by the user. For example, in Spain it is possible to define the typical 2.0DHS tariff (hourly discrimination) for a typical house.

Stay tuned for new enhancements like the three-phase ozm launch!

Paper published in journal Sensors (MDPI)

This is the second specific paper on the openzmeter device. It describes in detail its hardware architecture and provides measurements in a real scenario. Likewise, a comparison is made with commercial and professional devices that reveals the accuracy of the measurements obtained according to international standards.

Cite as:

Viciana, E.; Alcayde, A.; Montoya, F.G.; Baños, R.; Arrabal-Campos, F.M.; Manzano-Agugliaro, F. An Open Hardware Design for Internet of Things Power Quality and Energy Saving Solutions. Sensors. 201919, 627.


An important challenge for our society is the transformation of traditional power systems to a decentralized model based on renewable energy sources. In this new scenario, advanced devices are needed for real-time monitoring and control of the energy flow and power quality (PQ). Ideally, the data collected by Internet of Thing (IoT) sensors should be shared to central cloud systems for online and off-line analysis. In this paper openZmeter (oZm) is presented as an advanced low-cost and open-source hardware device for high-precision energy and power quality measurement in low-voltage power systems. An analog front end (AFE) stage is designed and developed for the acquisition, conditioning, and processing of power signals. This AFE can be stacked on available quadcore embedded ARM boards. The proposed hardware is capable of adapting voltage signals up to 800 V AC/DC and currents up to thousands of amperes using different probes. The oZm device is described as a fully autonomous open-source system for the computation and visualization of PQ events and consumed/generated energy, along with full details of its hardware implementation. It also has the ability to send data to central cloud management systems. Given the small size of the hardware design and considering that it allows measurements under a wide range of operating conditions, oZm can be used both as bulk metering or as metering/submetering device for individual appliances. The design is released as open hardware and therefore is presented to the community as a powerful tool for general usage.

First scientific paper published

The openZmeter team is completely delighted again. Recently, a new scientific article has been published in the prestigious journal Sustainability edited by MDPI. Our Ph.D. Student Eduardo Viciana did a great job and the result is his first international paper entitled “OpenZmeter: An Efficient Low-Cost Energy Smart Meter and Power Quality Analyzer”.  

It is open access and can be found in Please cite it as:

Viciana, E.; Alcayde, A.; Montoya, F.G.; Baños, R.; Arrabal-Campos, F.M.; Zapata-Sierra, A.; Manzano-Agugliaro, F. OpenZmeter: An Efficient Low-Cost Energy Smart Meter and Power Quality Analyzer. Sustainability201810, 4038.


Power quality and energy consumption measurements support providers and energy users with solutions for acquiring and reporting information about the energy supply for residential, commercial, and industrial sectors. In particular, since the average number of electronic devices in homes increases year by year and their sensitivity is very high, it is not only important to monitor the total energy consumption, but also the quality of the power supplied. However, in practice, end-users do not have information about the energy consumption in real-time nor about the quality of the power they receive, because electric energy meters are too expensive and complex to be handled. In order to overcome these inconveniences, an innovative, open source, low-cost, precise, and reliable power and electric energy meter is presented that can be easily installed and managed by any inexperienced user at their own home in urban or rural areas. The system was validated in a real house over a period of two weeks, showing interesting results and findings which validate our proposal.

How to install your oZm in an Electrical Box

Ok, you have just received your brand new openZmeter and it’s time to install it. I must admit it’s not a straightforward task, but it can be done in some few minutes if you put attention. You need a screwdriver and a wire striping tool. Be patient.

Warning: be careful and do it at your own risk.

Some History about oZm (III)

This is the third and final entry about the OpenZmeter project history. You can read the first one here and the second one here.

After the first sketches and designs based on the BBB and own electronics (something homemade… everything is said), there was a step forward in quality with the arrival of Eduardo Viciana to the project. Thanks to his knowledge and experience in microcontrollers, electronics and low-level code, a much more professional approach was taken. oZm was completely redesigned and a new shield based on the micro STM32 was used. This microprocessor has several ADCs that sample the voltage signal. It is also responsible for communication via SPI with the Hall Infineon current sensor TLI4970. The samples obtained in real time are sent via USB to the NanoPi for further processing. The system synchronizes the phase of the voltage and current channel to avoid errors in the energy measurement.

openZmeter v1.2

In its current configuration, the system is able to perform current measurements with an accuracy of 1% and voltage measurements with 0.1%. As an example, the following figures are given:

Sample current waveform

Sample voltage waveform

This is how we close this list of posts related to the historical evolution of the project. Stay tuned for the next news!


También en español!!

Esta es la tercera y última entrada acerca de la historia del proyecto openZmeter. Puedes leer la primera aquí y la segunda aquí.

Tras los primeros bocetos y diseños basados en la BBB y en electrónica propia (algo casera… todo hay que decirlo), se produjo un salto de calidad con la incorporación de Eduardo Viciana al proyecto. Gracias a sus conocimientos y experiencia en microcontroladores, electrónica y código de bajo nivel, se pasó a un enfoque mucho más profesional. Se rediseñó completamente oZm, pasando a utilizar un nuevo escudo basado en el micro STM32. Este micro dispone  de varios ADC que samplean la señal de tensión. También se encarga de la comunicación por SPI con el sensor de corriente de efecto Hall Infineon TLI4970. Las muestras obtenidas en tiempo real son enviadas mediante USB a la NanoPi para su procesamiento. El sistema se encarga de la sincronización de la fase del canal de tensión y de corriente para evitar errores en la medición de energía.

openZmeter v1.2

En su actual formato, el sistema es capaz de realizar mediciones de corriente con precisión del 1% y mediciones de tensión con el 0.1%. Un ejemplo son las figuras siguientes:

Sample current waveform

Sample voltage waveform

Con esta información, cerramos esta lista de posts relacionados con el devenir histórico del proyecto. Estate atento a las próximas novedades!!

Some History about oZm (II)

This is the second entry about the history of the openZmeter project. You can read the first one here.

Once the interface was designed and concept tests were performed, the hardware definition phase began. Initially, and due to limited manpower with advanced knowledge in electronics, it was decided to make use of the Texas Instruments BeagleBone Black (BBB) board. Previously, some sketches were made based on some of Texas Instruments’ ADCs, although they did not happen to materialize. It was 2013 and the project was extended with the collaboration of Javier Clement and Vitaly. It wasn’t until 2015 that the project took off thanks to the collaboration of graduate in electronics Javier Rodríguez. The first designs of the shield on which the BBB would be placed began with him. Initially, a passive network was designed as a resistive divider to measure the voltage as well as a precision shunt resistance to measure the current.

oZm Shield v1 – 2015

We chose the BBB because it was one of the most powerful devices at that time. It also had built-in Linux installed as default, but the most important reason was its two PRU’s microcontrollers with which we could read and manage the voltage and current samples coming from the shield in real time. These PRU’s dumped the information directly into the RAM so that we could perform the necessary electrical calculations without any major problems. As a result of this work, some papers (in Spanish) were presented at the Sarteco 2015 Conference (here the presentation).

The fact is that the prototype was able to measure voltage, but not current due to a design flaw in which the specifications of the INA126 amplifier were not properly taken into account. This helped us to learn some lessons about how complex and delicate electronic design can be!

In the next and last entry, I will talk about the last stage, where a more professional and effective design is performed.


También en español…

Esta es la segunda entrada acerca de la historia del proyecto openZmeter. Puedes leer la primera aquí.

Una vez que se diseñó una interfaz y se realizaron las pruebas de concepto, empezó la fase de definición del hardware. Inicialmente, y debido a los escasos recursos humanos con conocimientos avanzados en electrónica, se decidió hacer uso de de la placa BeagleBone Black (BBB) de Texas Instruments. Previamente, algunos bocetos fueron realizados basados en algunos ADC’s de Texas Instruments, aunque no llegaron a materializarse. Corría el año 2013 y el proyecto se amplió con la colaboración de Javier Clement y Vitaly. No fue hasta 2015 cuando el proyecto tomó un mayor impulso gracias a la colaboración del estudiante de electrónica Javier Rodríguez. Con él empezaron los primeros diseños del escudo sobre el que iría insertada la BBB. Inicialmente, se diseño una red pasiva a modo de divisor resistivo para medir la tensión así como una resistencia shunt de precisión para medir la corriente.

oZm Shield v1 – 2015

Elegimos la BBB porque era uno de los dispositivos más potentes del momento. También tenía Linux instalado de serie, pero el motivo más importante eran sus dos microcontroladores PRU’s con las que podíamos leer y gestionar en tiempo real las muestras de tensión y corriente provinientes del escudo. Estas PRU’s volcaban la información directamente a la RAM de forma que podíamos realizar los cálculos eléctricos necesarios sin mayor tipo de problema. Fruto de este trabajo surgieron algunos papers (en español) como el presentado en las Jornadas Sarteco 2015 (aquí la presentación).

La verdad es que el prototipo llegó a medir tensión, pero nunca corriente debido a un fallo de diseño en el que no tuvimos en cuenta correctamente las especificaciones del amplificador INA126. Esto nos sirvió para aprender ciertas lecciones acerca de lo complejo y delicado que puede ser el diseño electrónico!

En la próxima y última entrada, hablaré de la última fase donde se realiza el diseño actual, mucho más profesional y efectivo.

Some History about oZm (I)

Today I start a series of posts about the origins of the project. I think it is good to remember the beginnings of everything in order to remember the road we have walked and to know why we first began and how we have survived to the present day.

I’ve been looking in my memory chest and the first email I have is from February 8, 2010. I was writing to Pedro Sánchez, who was then a graduate student on his Final year project.

When can you stop by my office and we can plan your project?  Initially, we could meet tomorrow afternoon….

It’s been over 8 years since then. This final year project was the embryo of what openZmeter is now. At that time, the project was called zEnergy. Z because it is the last letter of the Latin alphabet and Energy… for obvious reasons. I had already been thinking for some months about why in the middle of 2010 there was no way to have access to the energy data of my house and much less to the electrical service issues. Then I met Pedro who was about to finish his degree in computer science. My sister Conso introduced me to him and we agreed to tackle the subject under the umbrella of linux and open source software – what a good idea!

Sincerely, Pedro has been one of the most valuable people I have ever met in my life and I am very grateful to him for his effort and dedication.

Sheevaplug with Debian inside


As a result of his work and perseverance, a scientific paper was published at an IEEE congress held in Malaga (Spain) in 2011, the International Conference on Power Engineering, Energy and Electrical Drives. People bombarded us with questions because they really liked it. It was the beginning, although there was still a lot to do. In fact, the oZm as such didn’t even exist… they were all working ideas about the interface. The hardware arrived later, but the seed was already there! In order to be able to validate what we were doing, we relied on the powerful Sheevaplugs that we used as multipurpose embedded hardware at that time, since they were equally suitable for Asterisk PBX’s and for intrusion detection systems IDS.

zEnergy Dashboard

to be continued…


También en español…

Hoy empiezo una serie de posts acerca de los orígenes del proyecto. Creo que es bueno acordarse de los orígenes de las cosas para tener memoria del camino recorrido y saber por qué se empezó y cómo se ha llegado hasta el presente.

Me he puesto a buscar en el baul de los recuerdos y el primer email que tengo es del 8 de febrero de 2010. Me escribía con Pedro Sánchez, por aquel entonces alumno de proyecto fin de carrera.

Cuando puedes pasarte por mi despacho y planificamos tu trabajo???  En principio podríamos vernos mañana por la tarde…

Han pasado más de 8 años desde entonces. Ese proyecto fin de carrera fue el embrión de lo que hoy es openZmeter. Por aquellos entonces, el proyecto se llamaba zEnergy. Z porque es la última letra del abecedario latino y Energy… por razones obvias. Yo llevaba ya algunos meses pensando por qué en pleno 2010 no había forma de tener acceso a los datos energéticos de mi casa y mucho menos a las incidencias en el servicio eléctrico. Entonces conocí a Pedro que por aquellas fechas andaba terminando la carrera de Ingeniería Informática. Mi hermana Conso me lo presentó y convenimos en afrontar el tema baja el paraguas de linux y el software libre. ¡Qué buena idea!

Sinceramente, Pedro ha sido una de las personas más valiosas que he conocido en mi vida y le estoy muy agradecido por su esfuerzo y dedicación.

Sheevaplug with Debian inside

Fruto de su trabajo y constancia, se pudo conseguir una publicación científica en un congreso de la IEEE celebrado en Málaga (España) allá por 2011, el International Conference on Power Engineering, Energy and Electrical Drives. La gente nos frió a preguntas porque, la verdad, gustó mucho. Fue el principio, aunque todavía quedaba muchísimo por hacer. De hecho, ni siquiera existía el oZm como tal… todo eran ideas de trabajo sobre la interfaz. El hardware llegó más tarde, pero la semillita ya estaba plantada!! Para poder ir validando medianamente lo que hacíamos, nos valíamos de los potentes Sheevaplug que en aquella época usabamos como hardware empotrado multiuso, ya que igual valían para centralita telefónica Asterisk que valían para montar un sistema de detección de intrusos.

zEnergy Dashboard



Hello world!

oZm hardware

Hi there!!! Greetings from Almeria, a wonderful place in the Southeast of Spain. This is the blog for the project openZmeter (oZm) and will be used to share and document its progress.

The oZm project is an opensource initiative of the University of Almeria and the University of Granada to build a professional grade hardware for electric energy metering and power quality analysis. It was born several years ago with a main idea behind it: to help people understand their patterns usage and visualize the quality of the supplied power. Take a look at the main site here.

A wiki has been also created to share all of our knowledge during the past years.

Stay tuned for the updates and join our community!!