The emonTx v4 is an energy monitoring transmitter unit that can monitor up to 6 AC circuits using CT sensors and the OpenEnergyMonitor 1-3 phase voltage sensing unit. At it's core is a Microchip AVR128DB48 microcontroller - responsible for sampling the current and voltage waveforms and calculating the power and energy values. The emonTx v4 also supports temperature sensing and pulse counting.
Data from the emonTx can be transmitted over the 433 MHz RFM69cw radio link or read directly using a USB cable from an emonBase or emonPi. A number of adapter boards are also available to provide internal connectivity options via ESP32, ESP8266, Pi Pico W and Pi Zero W.
Key features
- Micro-controller: AVR128DB48 (VQFN 128 kb flash, 48-pin package)
- 3 voltage channels (via RJ11 connector top-right, interfaces with separate voltage sensing board, single phase firmware only at present).
- 6 CT current channels on the base board.
- Option to extend the number of CT channels to 12 via an additional extender board (firmware not yet developed for this).
- Precision voltage reference for the ADC to improve accuracy.
- RJ45 socket for pulse counter and DS18B20 temperature sensing.
- 3x 3-WAY pluggable terminal blocks for selectable temperature sensing, pulse or additional analog input.
- RFM69CW 433MHz radio transceiver
- DIP Switch to select node id
- USB-C power and integrated CP2102 usb to serial chip
- Serial and SPI pin headers breakout internally, designed for use with adapter boards.
The dimensions are slightly smaller than that of the emonTx v3 at 65mm long rather than 80mm.
The board is designed to support both single and full 3-phase electricity monitoring when used in conjunction with the relevant external voltage sensing board. And the CT extender pin headers should provide a cost effective way of gaining additional CT channels.
The on-board USB to serial chip will make it easier and neater to have a hard-wired installation linking the emonTx to a RaspberryPi based base station.
Or here on github:
- 6CT Expansion Board
- ESP8266 Expansion Board
- ESP32 Expansion Board
- Pi Pico Expansion Board
- Pi Zero ExtExpansionension Board
OpenEnergyMonitor Shop Support: support@openenergymonitor.zendesk.com
- The hardware designs (schematics and CAD files) are licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
- The firmware is released under the GNU GPL V3 license The documentation is subject to GNU Free Documentation License
- The hardware designs follow the terms of the OSHW (Open-source hardware) Statement of Principles 1.0.
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