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

[Bo Herrmannsen]

Hi

regarding the open energy system, i had to copy off their system since it did not support my heat meter.

i started out with onboard serial but i decided against it, major reason is that it takes up to much space, you need a 2nd iso connector to program it. What i did in the end was a FTDI connector and a FTDI programming cable, the usb plug has the chip built in.

also in this way it allowed me a 5*5 cm board. 

i can make a zip and send it to you all if interested. it should be ready for pcb fab put waiting for mike to get an extra set of eyes on it



/bo


Den 01/04/2013 kl. 12.10 skrev Stuart Poulton:

>> So, the question here, in my mind, is what is the power overhead of having a USB interface as "dead weight" in the AVR as opposed to perhaps an FTDI chip that's only powered from the USB bus when connected?
> 
> I know you can get the ATMEGA32U4 (same chip as a lenoardo) down to 0.04mA
> 
>>> Unfortunately all three radio modules now seem to be end of life.
>> 
>> Hmm. will have to keep an eye out for an alternative.
> 
> Some details about the EOL of some RFM products here 
> 
> http://blog.homelabs.org.uk/rfm12b-end-of-life/
> 
>> 
>> 1) AVR with built-in USB
>> 2) AVR with USB-to-Serial chip
>> 3) AVR only, and use a cable containing a USB-to-Serial chip
>> 
>> Option 1 being preferable, IMHO, especially as it opens up the possibility to do more with the USB interface. Maybe a PC application to program the schedule on the device, for example?
>> 
>> I've heard the AVRs with built-in USB can be a pain during development, though, because the USB interface goes down every time you reset the CPU after a download. This is the reason devices like the UNO have a separate CPU to provide the USB link, so both of your modules sound useful, perhaps at different stages in the development.
> 
> I've been thinking about this, USB adds to the cost of a chip, yet allows for more configurability, I think I'm moving toward a model where USB and RF are used, so USB + Power for those TRV's where it's possible to cable, RF + Battery for those where cabling isn't possible.
> 
> Stuart
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