For a while now we have been using the NanodeRF as our emonBase web-connected base station. The NanodeRF is great and has met our needs well. However using the ENC28J60 Ethernet chip does have some limitations.
We have through about having an emonBase option which supports the Wiznet Ethernet chip. This is the chip that is used in the official Arduino Ethernet. On the Wiznet chip the TCP/IP stack is implemented on the chip as opposed to on the ATmega328 as in the case of the ENC28J60, this means ATmega328 has a greatly reduced load, more application memory is freed up and the code is much simpler and brought in line with the Arduino Ethernet code examples.
In testing we have found the Wiznet chip to be more stable at holding a connection over a long period.
However the Wiznet chip is more expensive than the ENC28J60, what we need is a flexible emonBase unit which is interchangeable between the two Ethernet chips, enter the Open Kontrol Gateway (OKG)!
The OKG is a very flexible web-connected base station based on the ATmega328 which is totally Arduino IDE compatible (Arduino UNO bootloader). The OKG has been designed and manufactured by our friend Miles who runs Ciseco Plc
The OKG PCB supports multiple wireless options such as RFM12B, XBEE, XRF, RN-XV Wifi. There is also PCB footprints for expansions like a RTC, SD card and SRAM. Finally what attracted us to the OKG was the ability to easily choose between the ENC28J60 or Wiznet Ethernet chips:
|OKG ENC28J60 module|
|OKG Wiznet W5200 module |
We now have stock of the OKG in kit form in the OpenEnergyMonitor shop. The kits will come with an RFM12B wireless radio (choice of frequency) and a choice of ENC28J60 or Wiznet Ethernet chips.
The OKG with the ENC28J60 is almost hardware identical to the NanodeRF. NanodeRF emonBase sketches will run on the OKG with a couple of little changes.
See the OKG OpenEnergyMonitor wiki page for the changes required to make the OKG work with the RFM12B and OpenEnergyMonitor emonBase examples:http://wiki.openenergymonitor.org/index.php?title=Open_Kontrol_Gateway
Note: The wiki is still in beta, we will blog more about it once it's been a bit more polished. It's our hope that by using a Media Wiki for our more technical documentation people will be more inclined to contribute corrections and additions and the documentations should be easier to organise and maintain. The OpenEnergyMonitor login should automatically log you in to the wiki. Just make sure your logged into the OpenEnergyMonitor website before opening up the wiki page. Try clearing your browsers cookies if this doesn't work first time.
We are now stocking the OKG in the OpenEnergyMonitor shop: http://shop.openenergymonitor.com/open-kontrol-gateway/What about the Raspberry Pi!?
Don't worry we haven't overlooked the Raspberry Pi! We have successfully had emoncms running on a Pi
receiving RFM12B data from a USB JeeLink, we plan to blog more about this soon. We're currently with Martin Harizanov
to make a RFM12B to Raspberry Pi GPIO expansion board. The Raspberry Pi will make a very powerful emonbase/home energy server however it's quite a complicated little beast for beginners who have limited linux knowledge. We think there is still a need to also have a simpler Arduino based emonBase option such as the NanodeRF or OKG.
Here's another progress update on the emonTx SMT design.
This week I've sent the PCB CAD design files off to get a few prototype PCB's made. It's a very exciting moment, quite a milestone but also nerve wrecking! These prototypes will be assembled by hand and tested extensively. Eventually we plan to get the board ready assembled using factory SMT pick-and-place machines, selling the emonTX SMT as a kit is not an option! We don't plan to discontinue the current through-hole emonTx, we believe there is value in having a simpler through-hole kit version as an option.
It will be sometime before emonTx SMT's are rolling off the production line, there are many hoops which need to be jumped through before then, but getting the first prototype off the ground is a good step forward!
As a quick re-cap the main features of the emonTx SMT are:
Improved accuracy when monitoring low power levels
with a programmable gain op-amp input stage on the CT inputs..see blog post
Single power supply
- Half-wave rectifier AC-DC circuit to power the unit (under basic operation) and monitor mains voltage (enabling real power readings) from a single AC-AC PSU..see blog post
Direct USB programming - No USB to UART or FTDI cable required - built in USB host using the ATmega32u4 building on Arduino Leonardo design.
On-board Ethernet and multiple wireless radio options – RFM12B will remain the default option.
Pluggable-terminal block - Pulse-counting input, 2 x one-wire temperature inputs and other spare I/O broken out on a pluggable-terminal block.
Casing - designed to fit in a nice wall-mountable extruded aluminium case with laser cut fascias and external SMA antenna.
For more info, design notes and my general ramblings see my forum post