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I think you would probably be able to get a rfm device to communicate with the IAM's as there are some projects out there that have hacked the currentcost IAM's. but it's most unlikely you will be able to get a single rfm to do both as the protocols will differ.

Paul

I'll have a dig into the building blocks to see if I can find how this module decides what to decode. Do you know if the firmware on it is from the Open Energy Project or elsewhere?

My EMONBASE and EMONTX are close by so I could wire the connection directly and then use the module for receiving IAM's.

If you search for "current cost c2 protocol", you just might find some information. But as it's a proprietary protocol, it's more than likely that it's commercially confidential, and you'll have to reverse engineer it yourself (and then keep quiet).

My EMONBASE and EMONTX are close by so I could wire the connection directly and then use the module for receiving IAM's.

Well yes and no :-)

There are numerous less used(documented) ways of achieving your aim, however the normal "direct" connection between a emonTx and a emonBase is via the same single serial port the rfm69pi uses so on the surface it's one or the other. The easiest options are to use a usb<->serial for the emonTx or use a Jeelink to add another network.

Paul

There is a third way I guess which is to reprogram the Arduino box that translates the output from the Current Cost EMVIR's serial port and sticks it on the internet via its Ethernet port. As I can't get access to its original code this is a one way street and I don't know how to:

1)get the current cost Arduino sketch on the current box to copy it's serial port and stick it onto its Ethernet port

2)get the pi to receive the result, remove any extra history data it doesn't need  and stick it into EMONCMS

is anyone interested in working this lot out? I've found details on the net on how to get the box to run a standard Arduino sketch

The CC protocol is understood by rtl_433 and it certainly does look like it should be possible to make an RFM69 receive it. I'm interested in doing a similar thing with the Watchman oil tank monitor, which also uses FSK. (For the Watchman, the original receiver unit uses a Si4320 which is basically an RFM01 anyway.)

Getting a single RFM69 to receive both at the same time is a lot more fun though…

The bit rate of the CC signals is a lot slower than emonTx — the period is about 250µs rather than 20.3µs. You'll need to use the RFM69 in "Continuous" mode and probably also turn off the bit synchronizer, but I think you can load a sketch onto Arduino side of the RFM69Pi which copes with that.

The more interesting problem is the base frequency of the transmission, and the bandwidth. I'm not sure for the CC, but in my case the oil tank monitor transmits at 433.90MHz ± 34kHz. I think the RFM69 does have AFC capability but you might need to set the bandwidth explicitly. So you might need to tweak the sketch on your emonTx to use the same bandwidth for its transmission as the CC device does, if you want a single RFM69 to receive both.

The easiest solution, assuming your CPU is up to it, is probably to just use an RTL-SDR dongle to receive both signals and do all the decoding in software with rtl_433.

Or maybe if you can get the RFM69 receiving the CC signal but not both at the same time, then hook up an RFM69Pi to the CP2102 UART board. It'll give you the serial port you need, and it looks like it can provide 100mA at 3.3V which I think should be enough to run the RFM69Pi as long as you're only receiving. So then you can have two RFM69Pis at the same time.

Thanks for the reply, its been a long time since I visited this thread!

In the end I repurposed the Current Cost Bridge I already had using a sketch I found on the net. I then used Openhab to translate the topic so the EMONPI version of EMONHUB would pull it into EMONCMS via MQTT. Its been totally reliable so far too.