Current Cost EnviR tear down
I may have to reverse engineer some parts of the Current Cost RF protocol. The first step may be to sniff the SPI bus between the EnviR’s PIC and the RF module. Hence I’ve taken the EnviR apart. Here’s what it looks like inside…
Disassembly
It’s very easy to pull apart. You just need to tease the back of the plastic case away from the front using a thin but wide screw driver:
To gain access to the main EnviR PCB it’s not necessary to unscrew the bottom of the case. But this is what the bottom looks like:
You can also remove the front plastic cover but it doesn’t reveal anything very interesting:
Inside
Here’s a close up of the PIC: a Microchip PIC18F86J90.
And here’s the RF module… it’s almost certainly an RFM01 running at 433MHz. We can be confident that it’s an RFM01 because Beeny has sniffed the SPI bus.
Note that this device almost certainly is not a Zigbee device, despite the fact that Current Cost are a member of the Zigbee alliance. How can we be confident that this isn’t a Zigbee device? For the following reasons:
- Zigbee nodes must be able to both send and receive. The EnviR can only receive.
- Zigbee operates at 868MHz in Europe. The CurrentCost EnviR operates at 433MHz.
- Zigbee data rates vary from 20 to 900kbps whilst the Current Cost runs at 4kbps.