More Energy monitoring - ATM90E26 Breakout

After designing and testing the ADE7763 based Energy Monitor Breakout Board, I started looking around for cheaper and more modern alternatives.I came across the Atmel ATM90E26 Smart Metering IC with dual communication options - UART/SPI and multiple metering modes (tamper proofing with current sensing on live and neutral). However the Evaluation Module (EVM) from Atmel is over-engineered and targeted at an enterprise audience. It is around $800 from Mouser Australia. I guess it needs to be so to comply with creepage/clearance requirements for handling 240V AC signals. This however puts it beyond the reach of a dabbler such as me.

Assembled ATM90E26 Reference design with low-voltage components

So I set about extracting the low-voltage only components from the Atmel Reference Design and placing them on a PCB. Atmel generously provided me with 3 sample IC's to go with my PCB's from OSHPark, thereby saving me around $750 in testing their IC.

Checking SPI mode - Mode 3 works

Then I went on the usual hunt for prior art in interfacing this code with a microcontroller and came across this post in /r/diyelectronics which interfaced the ATM90E26 to a Raspberry Pi. Ryzee sent me the code and assisted me in choosing the right SPI mode (mode 3 in this case) which lets a Teensy talk to the ATM90E26. The code is now available as an Arduino sketch.

ATM90E26 RMS Voltage mesurement test harness

I built a low-voltage test rig to see if the voltage ADC works okay and all seems to check out. Full blown Energy Measurement tests next. Meanwhile I have placed the couple of boards I have on Tindie to gauge interest for a larger batch. Let me know if you would like to test this modern Energy Monitor IC on the cheap.

Bringing back an old favourite - the Butteruino

After I had done some damage with AVR's bought from Dick Smith in 2002 on a breadboard, I moved onto the butterfly. I did a mini project measuring waterflow using thermistors for GroGuard. Then they lay disused in boxes until recently. I ordered a carrier board from Ecross and put together a handy proto-typing platform, except the serial port on the butterfly I have seems to be obstinately broken.



This did not stop me from getting some software together for loading code onto it. Since everybody has caught the Arduino fever. I decided to go with Wiring and the Arduino IDE to develop for the butterfly, fortunately the Butteruino project has already done a lot of the hardwork for me, I just upgraded the changes to v22 of the Arduino IDE release. The patch should go live on SVN soon. Till then if you have a butterfly and want to test it with the Arduino IDE get it here.

Now the assembled carrier will lie in boxes till I work up the courage to order some more old butterfly's from Digikey.
In spite of all their peripherals and fancy demo code, the butterflies suffer from the weirdness of the joystick, lack of FTDI for direct USB connection and overall fragility. Still they are excellent for long-term, low-power data logging applications, may be coupled with an Xbee. I believe given slightly different design choices, a better IDE than AvrStudio, no funny press the reset button and pray code uploads, the butterfly could have beaten the Arduino back then. I will look into making the flow sensor again once I get my hands on a working butterfly and develop some more Eagle skills.