Wednesday, May 18, 2016

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.

2 comments:

Kishan Joshi said...

not able to get proper current can you please guide me for calibration procedure?

Pallav Aggarwal said...

Hi, I am using your breakout board from OSHPark, powered it up correctly, I see Vref 1.256V, Oscillator working on Oscilloscope.
MMD0=1, MMD1=1, UART mode.

I am able to send SoftResent command and getting a response but for all other commands, there is no response. I have tried both 2400, 9600 bauds.

I have tied SCLK to GND and CS Pin High as recommended in the datasheet.

Is there anything I am missing?

Could you please guide me?

Best Regards,
Pallav Aggarwal