Sunday, November 23, 2014

Power Plug Energy Meter - Now wireless!

This is the second post about my work on the cheap China-style energy meter hack.
My last post covered how I with a logic analyzer successfully (but not in the safest way) sniffed the SPI-transmission on the device and managed to decipher the data. And then how I used an Arduino Nano to do the sniffing for me with an interrupt driven approach. The Arduino  translated the bits and bytes to power and voltage values that it continuously printed on the PC's Serial monitor via an USB-cable.

The next obvious step in this project is to get the energy meter to transmit the data wirelessly. Not only would this mean that I could grab data from several energy meters simultaneously, but it also creates a safe way of debugging the device since my previous setup (which I abandoned after reading some of the comments on Hackaday.com) meant connecting the mains neutral to the computers ground (do not try this at home!!!)

Today's post will cover how I managed to get an Arduino pro mini (3.3V) to sniff the energy meters SPI and transmit the data wirelessly with a nRF24L01+ to an Arduino Nano connected to a computer. The neat thing with this setup is that the Arduino pro mini and the nRF fits perfectly within the casing of the energy meter, and are both driven by the internal power that charges the rechargeable battery that you'll find in the meter.


The total cost of components for each energy meter is:
Energy meter             £7.97
Arduino Mini 3.3 V       £2.58
nRF24L01+                 £0.99   (choose the black + version)
A capacitor + cables   pretty much free, say £1

which comes to a total of £12.54 per unit!

Plus one computer connected node, or a raspberry pi with a nRF24L01 to receive the transmissions from all the energy meters.

Arduino and RF24.h
As mentioned in previous blog-posts I have worked quite allot with the nRF24L01 and AVR's, writing my own libraries and so on. But since this is my first Arduino-project I wanted to learn how to import and use other peoples libraries. Since I am still a newbie in programming, I always have to learn everything from scratch, and nothing ever works as supposed to when I try to follow a tutorial...


I started out by setting up two Arduino Nanos according to this guide and running the example code at the bottom of that page, and as expected - it didn't work. 



Debugging
1. Do I have a working SPI-connection?
I had followed the explanation in the guide i linked to above, on how to install the RF24.h-library and it all seamed to work, I definitely had a working SPI-connection between the Arduino and the nRF since I could print out all the registers, and modifying them also worked...

Took me a while to figure out that I had to download and include the file "printf.h" and call "printf_begin();" to print out data from the nRF to the serial monitor... and why, why, why are they using the "protected" attribute  for many of the functions??? For example get_status is a very useful debug-function and should not be protected!

2. Am I using the correct hardware setup? 
As always I hadn't used the exact components as the instructions said, in my drawer I could only find one 47 uF 24 V  and one 100 uF 16 V capacitors. Well in the guide it sais:
"Connect a .3.3 uF to 10 uF (MicroFarad) capacitor directly on the module from +3.3V to Gnd (Watch + and - !) [Some users say 10 uF or more..]"
And I read 10 uF or more....

Anyways, I thought that this should work, since I have used these capacitors before on the nRF, but not with this library and not with Arduino...

3. I found a working code
Yay, suddenly i found a working code, the "pingpair" example that comes with the NRF.h-library worked with my setup!

4. Why does only Pingpair-code work? 
I started stripping the Pingpair-code of its components, and found that my setup was only working when it got into receiving mode in between every transmission... strange, but keeping in mind that I was using bigger capacitors I figured it had something to do with the capacitors not have time enough to recharge/discharge.

I think this is what happened:
When the Arduino calls the "Write" function, the library runs the "startWrite"-function which powers up the nRF and has a predefined delay of 150 us (wait for the nRF to power up) before it starts transmitting the data.
It turned out that this delay was not enough for my setup, so when I changed this to 1000 us (1 ms), the code worked like a charm even without the receiving functions in between! To do this modification, I opened the RF24.cpp-file (in the arduino Sketchbook libraries folder) with notepad, changed the delay, and saved the file.



Arduino Mini
Just as I managed to get a working Arduino code for the nRF, two Arduino Mini 3.3 V landed in my postbox, awesome timing!


One little problem; the Arduino Mini does not come fitted with an USB to Serial-chip to enable programming over USB.... luckily for me I had an USB to Serial adapter laying around (used for debugging AVR's, as I wrote about in this tutorial-post) that I could use to program the Arduino.

Here's a pic of when I have soldered an nRF to the Arduino and uploading code with the USB to COM adapter via a breadboard (out of sight) so the colored cables does not match the pins...


Off course this didn't work straight away either, I found out that when using this kind of FTDI-adapter you have to press the reset-button on the Arduino Mini just when the Arduino-IDE starts to upload the code to get it working! A better buy would be one of these which comes with an automatic reset-pin ("DTR").

I soldered the nRF to the Arduino, and glued them together with some hot-glue, which was also used to attach the unit to the power meter. Plenty of unoccupied room in the meter behind the LCD, and perfect position for a wireless transmitter!


Here you have the wire diagram: 

I started off by just uploading a simple transmission code on the Arduino mini, that would send a dummy byte once a second to confirm a working setup. I  soldered everything together,  plugged the meter into an outlet and kept my fingers crossed as I watched the Arduino-Serial monitor connected to the receiving unit, and.... noting (of course!)

After several hours of debugging, (I thought I had burnt the nRF by hooking it up directly to the power-meters VCC-pin)  It turned out had I accidentally  uploaded a non-working code to the Arduino Mini.... FAIL!!!

I had cleaned up my working code, and shifted some parts around, it seems like you can't open the writing/reading-pipes on the nRF before you set the datarate/payloadsize/PALevel...

Anyway, the setup I found working is grabbing the power directly from the battery (3.6 V soldered to the underside of the PCB) rather than the VCC-cable (which i think is a bit flaky, and is connected to the RAW-pin on the Arduino, which has a built in 3,3 V regulator. I'm not sure this modification is necessary, but it ensures that the nRF and the Arduino gets 3.3 V. (The pictures above are not connected to RAW, but the Arduino's 3.3 V)

Here's whats transmitted to the computer connected Arduino and printed in the Serial monitor:


I have spent some time looking at ways to store and plot this data in the cloud. One interesting approach is to send the data to a website like http://emoncms.org/ and use there ready to use energy-viewing graphs. With the help of a small python-script I wrote, I can easily send the data from my raspberry pi-server to my account on there website where I have the option of making graphs.

I have also been working in the program called "Processing" which is pretty much the same as Arduino-IDE but for graphing and doing stuff with the data.
I have so far programmed a working graph that shows the data output from up to 6 wireless energy meters, it  also logs the data with timestamp to a csv-file. See the processing-code at the bottom.


Above you see a screenshot of when I have plugged in two energy meters (1 and 2). Nr 1 shows a soldering station which i obviously changed the power on allot during the readings. Nr 2 is a 4-step lamp that i flickered from 3 to 0 to 1 to 2 to 3. as you see i didn't stop at 0 for a very long time, so the graphed mean value stopped at ~10W.

You might wounder why the red and green line (nr 1) sometimes differ? That's because I have the meter to transmit the average=red and the maximum=green power readings on every third power reading. This interval is easily changed by typing 1:1 or 1:4 to change the interval on meter 1 from to 1 or to 4 readings in between transmissions.

I had a hard time figuring out how to transmit this new interval from the computer nrf to the meter, because if I in between every transmission changed the nRF to a receiver, the power consumption would cause the whole meter to stop working.

This time I had to do some serious thinking, and I ended up using the possibility to alter the autoAck-payload. A function that normally sends an "OK" from the receiving nrf back to the transmitting nRF to confirm the transmission. I found out how to alter this value to send something like a "2" instead, or some other integer that would be a new interval. This was exactly what I needed, See the code at the bottom!

Her's the working Arduino code, first for the Energy Meter then for the computer connected receiver-Arduino. At the very bottom you have the processing code:


Here's the code for the receiving Arduino (connected to computer via USB)

And finally the Processing code that can be used to read and write to the computer connected Arduino through its serial connection (over USB)

48 comments:

  1. This comment has been removed by the author.

    ReplyDelete
  2. Hello,

    Very nice work with the wireless implementation !!
    Do you happen to have or know where can I see the schematic for the current analysis part ? (not the Display/MCU board), I'm trying to make something like that from scratch, without the display builtin, that will just send the data through wifi/bt/rf or similar.

    ReplyDelete
    Replies
    1. You might get something out of this: http://hackaday.com/2011/03/28/open-source-wireless-mesh-networking-energy-meter/

      Delete
  3. Hi,
    I'm trying to help a group of students replicate your project, to use it to measure the energy we're generating using a bicycle. We're not as knowledgeable as some of the readers on Hackaday, and are having trouble seeing all of the connections you made between the nRF, the Arduino, and the power meter. Are you able to post a schematic, or more pictures? Any guidance you could provide would be greatly appreciated. It's a great project and we have all the pieces, just having trouble bringing it together. thanks, Keith

    ReplyDelete
    Replies
    1. I updated this post with a wire diagram.
      Good luck with the project!

      Delete
  4. Thanks very much, we really appreciate it. We'll try to post some pictures, eventually.

    ReplyDelete
    Replies
    1. oops, draw the yello and blue cables wrong... see the updated wire diagram!
      looking forward to see your work!
      /Kalle

      Delete
  5. Got it, thanks. Also, can you tell us where the pink cable ends up on the power meter? It lands in the little cluster of SMD components, but we can't tell exactly where. thanks!

    ReplyDelete
    Replies
    1. Solder the pink cable to the under side of the + side of the battery. (or directly to the battery if you want)

      Delete
  6. Any idea if we can wire up a +3.3v regulator in there for some extra power? I'm not really sure and I don't want to experiment (with my life) :D

    Thanks and keep it up!

    ReplyDelete
    Replies
    1. I'm trying to save space and trying not to use a USB power supply in there!

      Delete
    2. The regulator inside is a WS78L05, should I change it with a beefier 5V one and see what happens? Should I wire one in "parallel"? Sorry for the 3 comments, I'm excited :D

      Delete
    3. You should not change the 3.3V regulator to a 5V one, that'll probably fry the main cpu on the display-board.
      I guess you could wire a 5V one in parallel but what's the point? maybe you can get more power like that, byt i guess it depends on the parts before the regulator as well? (im not an expert in electronics)
      are you using an 5V version of Arduino? Both the ESP8266 and the nRF24 needs 3.3V anyway and the regulator inside has sufficiant power to run a nRF24 like i did. Might be worth trying for the ESP though!
      Looking forward to follow your progress =)

      Delete
    4. Aha, I see that the S78L05 is a 5V one! that explains the zener dioedes (taking it down to 3.3V) next to the battery.

      Delete
  7. This comment has been removed by the author.

    ReplyDelete
  8. I managed to get it working with an ESP8266 :) Not directly (my programming skills are insufficient) but with the Arduino as a translator in between.

    I used the code from the previous blogpost. It already had a nice spot "Place nRF24L01 transmit code here" ;) So i grabbed some Arduino + ESP8266 sketch from the internet (Instructables) and got quite annoyed when i couldn't get it working. Then i saw that it was missing quite some essential basic HTTP things (like 'HTTP 1.1' and mentioning: "Host: xx.xx.xx.xx" etc.). After fiddling around for a few hours i managed to get it send the power to my home automation system, 'Domoticz'.

    The code is far from done, but i am very proud, especially when i saw the value being updated for the first time :D

    You can find the Arduino code here:
    http://pastebin.com/G6dArPfv

    Todo/bugs:
    - The wifi connecting part isn't working.... I connected the ESP8266 to my network by hand (issueing the 'AT+CWJAP' command) and it remembers it. But ofcourse it has to be made working in the code.
    - I am not sure about the 'dtostrf' part. I looked into 'dtostrf' function and saw the parameter 'minimalWidth', but i am not sure about how this works in this situation. Sometimes the power consumption can be 1 wide, with 1 decimal (5.5W), but also 4 wide with 1 decimal (1234,5W)
    - Code in general is a mess. I need to implement some variables, some things (IP and port) are still hardcoded now


    But i think my code is a useable start. Domoticz uses plain GET-requests, so it should be easy to adjust to your own situation. Maybe call a PHP-script to dump it in a (MySQL) database or something.

    P.S. The meter/this code seems quite accurate to me. I connected a phone charger (Samsung micro travel charger) without a phone connected and it showed 0,2W. Some 433Mhz wireless relay plug showed 0,7W. Very nice for such a cheap meter.

    ReplyDelete
    Replies
    1. Now only a solution is needed to power the ESP8266 from within the meter casing.... I now have it powered by an external 3.3V powersupply.

      The Arduino is powered by connecting it to GND and to the OUTPUT pin of the 78L05 regulator. But already tested it, and the 78L05 can't power the meter, the Arduino AND the ESP8266... It just isn't strong enough :(

      Delete
    2. Well done!
      I will definitely give the esp a go when i have the time!

      Delete
    3. I worked some more at the code, the Arduino <> ESP8266 part should be quite solid now. Also found out how to use BitBucket, so posted it there: https://bitbucket.org/frankiepankie/china-powermeter/src/master/esp_arduino.ino

      Two things i need your help Kalle,
      The code almost always shows "U: 228.6V
      I: 142772mA
      P: 32640.5W"

      Is there a possibility to just return 0W here? So i can send this to my home automation package? Or should i just implement something like "IF P=32640, THEN P=0" ?

      And another, annoying, thing is, the meter doesn't always seems to get back 'in sync'. Normally after ~10 measurements it would call the Arduino function that sends the data. But when i first connect a LED-bulb of 6,5W and then a 50W halogen bulb this doesn't happen. After i reset the Arduino, and with only the 50W halogen bulb, it calls the function like normal, after ~10 measurements.
      Any idea how to fix this? Maybe clear some 'cache' of measurements or so?

      Delete
    4. I meant that it shows 32640W when nothing is connected. I now put in a workaround, that when P >= 32640 then the code should assume nothing is connected and send 0W to my home automation.

      I also discovered something funny. The meter has some difficulties with a weird load like a CFL-bulb. When i look on the display i see a powerfactor of 0,5. The display indicates 0.112A and jumps between 13.6W and 14.4W, but the Arduino code says 59mA and 13.4W. So the Arduino code seems to be more accurate than the display of the meter itself :D

      Delete
    5. Hi!
      My meters are also sending a very high value when not connected. If you have a look in my Processing code, i deal with the error checking on line 151 & 195. But you might as well do it in the meter like you do!

      The strange behaviors might be due to noise from the LED-bulb. maybe you can find some way of blocking that noise with capacitors? Read more here

      Delete
    6. This seems like a great project. Is the .ino code meant to be run on the ESP8266 directly (using the Arduino IDE)? If not, what version of the AT firmware are you using? Has anyone gotten the WiFi connection part of the code working?

      Delete
  9. Kalle

    I don't know if you ever identified the energy meter IC used.
    It seems likely to be a Cirrus Logic CS5460... . Chinese equipment seems to use CS5460C-ISZ, whereas most Western data sheets seem to be for the CS5460A - I have not yet found if there are any differences. The CS5461 also looks very similar and maybe essentially identical.
    Data sheet for CS5460A here http://www.cirrus.com/en/pubs/proDatasheet/CS5460A_F5.pdf . | Of possible interest is that pins 22 & 21 MAY provide pulses proportional to Watts of load and they can show if power is negative (into grid) or positive (into load). These pins may be used in several modes including higher frequency for electronic interfaces or lower speed for stepper motors or other electromechanical devices. Using just these pins (and only EOUT on pin 21 for load only applications)(which would match most needs) an extremely simple interface can be built. I do not (yet) know what mode these pins operate in in these meters so it MAY not be useful as is.

    regards - Russell McMAhon - (Adjust slightly -> apptechnz at gmail dotcom)

    ReplyDelete
  10. Since a few days it is possible to run Arduino code native on the ESP8266. Maybe the Arduino isn't then even needed anymore for this project.
    For more information, see here: https://github.com/esp8266/Arduino/

    ReplyDelete
    Replies
    1. Did anyone actually get this working without the arduino? I'm about to try to build one and my goals are: 1.) esp8266 2.) no arduino 3.) all encased in meter housing (running off of meter's power) 4.) also measures temperature 5.) uploads data hosting service (thingspeak or other) though local wifi.

      I saw the github expample on the code to run arduino core on the esp8266, so I think that's doable.

      I didn't see anyone get this to work, but shouldn't there be 3.3v or 5v somewhere in the meter already? Maybe we'd have to worry about pulling more current than it was designed for and burning it up. I guess it's not all that expensive to try it and see.

      Measuring temperature should be easy since the 8266 support I2C... I'll just use a ds18b20. That's what i've been using in other applications.

      Any other pointers are helpful, as I'm relatively new to this. Only have one other project under my belt and that was putting 2 temp sensors on a Pi2 that upload to thingspeak. The reason I want to do this project is that I'm monitoring my greenhouse temp already with said project. I thought it would be great to know when the heaters are on and off exactly, and how much current the pull. I guess I know they pull about 10 amps, but what fun is it to not have live data! ;)

      Delete
    2. Hi!
      I havent't yet tried to put an ESP in the meter, but I have been working on some other projects where I used Arduino IDE to program the ESP without any problems!
      I connected two digital thermometers (DS18B20) to the esp and got them to push data to a website with a given interval - much similar to your project.
      If you read the coments above, the internal 3,3v power supply is of no use since the current demand of the ESP will drain the meters low voltage cirquit and make it useless. I think i will try and fit a tiny 3.3V ac/dc converter in the meter to make my own low voltage cirquit! ( ebay link )

      Delete
    3. I have it working now with a standalone ESP8266 programmed with the Arduino IDE, see here: https://github.com/HarringayMakerSpace/WiFiPowerMeter

      Thats publishing the data to https://data.sparkfun.com/streams/5JpMjVaVVjcz5EA7ORjK every hour.

      Delete
    4. Hi, I've that code for the ESP8266 based Wifi version of this in my public Github repo and someone has raised an issue asking about non-ohmic loads. Beyhond me, can you help with the question? See https://github.com/HarringayMakerSpace/WiFiPowerMeter/issues/1

      Delete
  11. Hi all ! I have problem with the processing code that can be used to read and write to the computer connected Arduino through its serial connection (over USB). I copied the code right from the post.

    Here is a screenshot : http://s4.postimg.org/42et8zv4d/Screenshot_2015_05_30_08_54_10.png
    And here is the error message : http://pastebin.com/nSV8hA94

    ReplyDelete
    Replies
    1. You cannot run this code in the Arduino program, install Processing.exe see link in blog post above!

      Delete
  12. And I have the same problem with the code for the receiving Arduino (connected to computer via USB).

    Screenshot : http://s27.postimg.org/w0xnb4n9f/Screenshot_2015_05_30_09_16_10.png
    Error Code : http://pastebin.com/zYs25wWc

    ReplyDelete
    Replies
    1. Read the blog post again, and you'll see that this function is protected, the picture you posted even has a comment into the code where I wrote how to change protected to public!

      Delete
  13. Hello Mr.Kalle Löfgren

    Can you help me do a project for payment? or can you refer me to someone.

    i want to use this energy meter with built in serial port and manufacturer supplies instructions(look below " ").

    Read energy: C0 A8 01 01 00 (Computer sends a request to read the energy value)
    01 86 9f 00 00 (Meter reply the energy value is 99999wh)

    http://www.ebay.com/itm/281655199920


    I want an arduino with back up battery to pull Kwh from two meters through serial connection, log it and compare if M1>M2 relay(230V 16A) closed

    Full instruction here in a word file.
    sendspace.com/file/ij7w29

    ---------
    6. Read the energy
    Send command: B3 C0 A8 01 01 00 1D
    Reply data: A3 01 86 9F 00 00 C9
    Note: Reply energy data is D1D2D3 = 01 86 9F, converts 01 86 9F to decimal is 99999, so the accumulated power is 99999Wh.

    Best Regards

    ReplyDelete
    Replies
    1. Hi!
      That sounds like an doable project... but before I can help you I need to know what you want help with, and how you plan to do this? Send me your email so we can move this conversation from this comment field!
      /Kalle

      Delete
    2. This comment has been removed by a blog administrator.

      Delete
  14. Good afternoon. :) We are currently making a project regarding smart metering. Can you recommend microcontrollers that have built-in wattmeters? Thank you.

    ReplyDelete
  15. I tried to repeat the experiment. did not work.You can send mail to the project completely (from the library) in my mail.

    ReplyDelete
  16. Kalle
    Did you see this comment re IC used?

    "I don't know if you ever identified the energy meter IC used.
    It seems likely to be a Cirrus Logic CS5460... . Chinese equipment seems to use CS5460C-ISZ, whereas most Western data sheets seem to be for the CS5460A - I have not yet found if there are any differences. The CS5461 also looks very similar and maybe essentially identical.
    Data sheet for CS5460A here http://www.cirrus.com/en/pubs/proDatasheet/CS5460A_F5.pdf . | Of possible interest is that pins 22 & 21 MAY provide pulses proportional to Watts of load and they can show if power is negative (into grid) or positive (into load). These pins may be used in several modes including higher frequency for electronic interfaces or lower speed for stepper motors or other electromechanical devices. Using just these pins (and only EOUT on pin 21 for load only applications)(which would match most needs) an extremely simple interface can be built. I do not (yet) know what mode these pins operate in in these meters so it MAY not be useful as is.

    regards - Russell McMAhon - -> a.p.p.t.e.c.h.n.z@gmail.com)

    ReplyDelete
  17. Thanks to Karl's work and other comments here, I took a stab at this as well.
    I read over datasheet and looked at logic analyzer traces from startup, and have quite a few observations.
    I re-implemented the spi-bitbang reading and doing things a little bit differently. Timing was tricky because we dont have any real start/end framing (like SS), so have to infer the stop/start from the longer inter-frame clock pulse.
    I have started a sketch with nrf24l01 -> raspberry pi integration here:
    https://github.com/zerog2k/power_meter_cs5460a/blob/master/power_meter_cs5460a.ino

    Hopefully in next few days, I'll put together a short write up of the analysis of the comms (register transfers, etc) along with a raspberry pi python script which i'm using to receive at the other end.

    ReplyDelete
    Replies
    1. Put in a write up with details of my observations along with the python script.

      Enjoy...

      https://github.com/zerog2k/power_meter_cs5460a

      Delete
    2. Thank you so much this!
      Have you integrated the values to any automation system?

      Delete
  18. Hello, I've got one these meter and its not working anymore. Can you please help? maybe I need to change the battery am not sure. thanks a lot. Ateeq

    ReplyDelete
  19. Hi, very nice blog. I've borrowed the same electric power meter from china.
    And try to make the same with a produino and nrf24l01.

    When i openend my version of the energy meter i had some different markings and 9 pins ribbon

    the label from top to bottom are:
    -VCC ,-SGND, -CS5460-reset, FREQ, CLK, SDO, SDI, EE2, EE1

    when i google on CS5460 (text by reset label) i see an energy chip where they talked about on arduino.cc
    this is the Cirrus Logic 5460

    http://forum.arduino.cc/index.php?action=dlattach;topic=276830.0;attach=101637

    The data sheet possible let us do some other magic to het chip (mine is scratched blank).

    Greets Danny

    ReplyDelete
  20. Hi, very nice blog. I've borrowed the same electric power meter from china.
    And try to make the same with a produino and nrf24l01.

    When i openend my version of the energy meter i had some different markings and 9 pins ribbon

    the label from top to bottom are:
    -VCC ,-SGND, -CS5460-reset, FREQ, CLK, SDO, SDI, EE2, EE1

    when i google on CS5460 (text by reset label) i see an energy chip where they talked about on arduino.cc
    this is the Cirrus Logic 5460

    http://forum.arduino.cc/index.php?action=dlattach;topic=276830.0;attach=101637

    The data sheet possible let us do some other magic to het chip (mine is scratched blank).

    Greets Danny

    ReplyDelete
  21. Completed project (ESP8266) WiFi Watt Meter:
    https://github.com/AlexeySofree/WiFi_Watt_Meter

    ReplyDelete
  22. vitality compliance,energy calculation,energy estimation services,title 24, title 24 report,title 24 vitality calculation,energy analysis,California vitality count administrations.
    california title 24

    ReplyDelete
  23. The California Energy Commission is in the process of adopting new building standards for Title 24 for new homes and buildings.california title 24

    ReplyDelete
  24. thank you for sharing good information about energy meter

    ReplyDelete