A nice way using the emonTx Shield and log the data

As I had an unused Arduino wireless development platform (XBee and nRF24L01 module interface, Ethernet (PoE support) and MicroSD socket) lying around so I orderd the emonTX Shield PCB to use it together.

I just needed 2 channels and no onboard RF link so I did not populate all of it.

Worked as expected with a RFM12 adapter and as a small webserver to show the data.

Later I wanted a solution with longtime logging of the data so I chose the Seeedstudio Stalker Kit, an Arduino made for logging. It has a buffered RTC with internal temperature sensor, a LiPo charge controller, mini solar-panel connector, XBEE-Socket and MircoSD socket and some other stuff.

One problem I was running into was that it just operates at 3.3V level and at 8 MHz so the software had to be honed a bit. At the moment it does not transmit as I had some problems with the correct usage of the XBee WiFi Modul (esp. uploading to cosm) and the energy management of this XBee but it's used just as a logger right now.

So the the IRQ of the RTC wakes the Stalker every chosen time (1 min, but could be 1 h, 3 days, every week too), collects the data from the sensors (2 non-invasive AC current sensor 30A and 2 external I2C temperature sensors, 1 I2C humidity, 1 I2C air pressure sensor, the internal temperature, voltage level of the battery, charge control status (charging on or off), writes it together with a leading RTC time stamp to a *.csv file on the 1GB MicroSD-Card (and to the serial port if connected so with a FTDI-USB modul it can be monitored at a computer, or send by e.g. a XBee SPP Bluetooth module) and goes back to sleep using the common power saving modes.

Post processing can be done by reading the MircoSD-Card and importing the data with Excel or a similar program.

Hope that helps someone.