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.
