[OpenTRV-dev] V0.2-Arduino: getting started

[Kevin Wood]

Hi Damon,

A few musings on using an AVR...

It might be worth a read of the notes here if you haven't come across it:

http://openenergymonitor.org/emon/emontx

No personal experience but a similar beast based loosely on an Uno. 
There are some notes about optimisation of power consumption there which 
might be worth a read.

I've never used an Arduino but I've used AVR devices quite extensively 
using just the GNU toolchain, AVR Libc and AVRDude to program them using 
an STK500. Arduino adds a nice development environment and a boot loader 
to allow the chip to be programmed through USB / RS232, as I understand 
it. I must pick up an Arduino and have a play sometime.

Unfortunately I don't know a lot about PICAXE.

There are a couple of AVR libraries around to drive the RFM12. I did try 
to get one working with the RFM01 and RFM02 but the latter devices are a 
real pain to drive in comparison to the RFM12 and I haven't (yet!) 
cracked them. I think an RFM12 will connect straight to the I2C pins on 
port B of the 328.

I've got some C code that drives Dallas 1wire temperature sensors from 
an AVR, by the way. I use that in an AVR based PID controller I made for 
my home brewery.

The UNO has a separate AVR handling the serial port. I wonder how easily 
the power supplies to this can be separated from that to the AVR device 
running the "user code", as this will no doubt affect the current 
consumption adversely. It might be that it'd be best to knock up a board 
or two with an ATMega328, RFM12, Onewire device, etc. and use the UNO to 
program it?

Or just buy one from openenergymonitor.org, of course.... ;-)

Cheers,

Kevin

On 30/03/13 12:31, Damon Hart-Davis wrote:
> Hi,
>
> I'll need some help getting going on this.
>
> Right from the outset I'd like to build something compatible with battery (and RFM23) voltage, relatively power-efficient, and that can share peripherals (I2C and SPI) with the PICAXE version for simplicity maintaining two stacks, and that is end-user reprogrammable.
>
> How should I start?
>
> (I have an UNO and a Leonardo on my desk, waiting.)
>
> Rgds
>
> Damon
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