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--- spark_abacus [2017/01/20 21:09] – [Orange Pi] kingkevin
+++ spark_abacus [2017/01/21 20:59] – add DDM100TC kingkevin
@@ Line 23: / Line 23: @@
 Compared to the [[spark_counter#peacefair_pzem-004|PZEM-004]] it comes without display and buzzer, but is much smaller.
 Else it uses the same design and chip.
+===== DDM100TC =====
+The [[http://www.china-huabang.com/en/product-show.asp?id=31&tt=101|DDM100TC]] (you can find it under different brands) is a 3-phase 4-wire electricity meter.
+The meter provides:
+  * 1 LCD to show the energy used in kWh (with a precision od 0.1 kWh)
+  * 3 LEDs to show which phase powered (L1, L2, L3)
+  * 1 LED to show the direction to the current (reverse if REV is on)
+  * 1 LED to show impulses as energy is used
+  * 1 S0 interface to output impulses as energy is used
+The S0 interface (labelled TEST on the side) allows me to collect the energy used on my micro-controller.
+Connect the + side (pin 8) to a positive voltage (i.e. +5V), an the - side (pin 7) to an input (with a pull-down resistor).
+Each impulse will generate a high signal (+2.5V in my case) on - for ~ 90 ms.
+The number of impulses indicates the energy used, and the time interval between impulses indicates the current power consumption.
+I chose one with a high impulse rate of 1600 impulses/kWh (= 1 impulse for every 0.625 Wh).
+There is also the DDM100TCR model with an RS-485 interface, but I couldn't find any documentation about the protocol messages, thus I wasn't interested in this feature.
 ====== EPS8266 ======