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.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWn8yFxHK4kLX2KYdYRcN1UoBish6yLHlXB07I5TkFyhAOb9UWHHkKvyjxDxhVMzusaUOvoEj-g3LUg9Lhl7shWMpA6WoFV4E4g6yLFPygoEKNPirTRDQYyRIP80qPGZcarL2zbW-8v2w/s320/IMG_20160509_211748.jpg) |
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.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQ2v6AvzICNOZ4oTm-zW_nEHEtcMPQny9o1huzj2xDQlM_EVbDCxpPI1Pilgt7r4y7jXVba4rBeSY0H353S9xW4jfjsgUhQARoKh8XllbqRsNmKZqRMLElvQOq0Hzrs5fWFQOuRs-7Pts/s320/IMG_20160509_131335.jpg) |
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.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjaaK7EMRleMPcseXLvQwIOB4jvuDEQYBF-4vXOLUyE2G3XAkOY5X5s5fxkWWgI_41tPDZIMmGAgI9jA5ewZn8AHfT-PF1VnrDa082iQJfPqz0EBgPsLqd-c4alwF80JcV5pyb9240IMj0/s320/IMG_20160509_200643.jpg) |
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.