[OpenTRV-dev] Energy efficiency

[Damon Hart-Davis]

There are many things I could do, but I've been conserving I/O pins for a rework such as this.

In fact, it is likely that given Mike's work with thermistors that DS18B20 can be replaced with a potential divider involving one, and that new divider and the one for the LDR could indeed only be pulled to a supply line long enough to take samples.  At a pinch that could even be driven from the same 1Hz RTC open-collector output, but I'm trying not to be too tricksy yet.

The voltage range of the DS18B20 annoys me more than its quiescent current consumption!

Rgds

Damon


On 22 Mar 2013, at 11:44, Stuart Poulton wrote:

> 
> On 21 Mar 2013, at 17:55, Damon Hart-Davis wrote:
> 
>> Hi,
>> 
>> Playing with the circuit a little, with a mod that would be slightly messy but not impossible with the current PCB, I have current consumption down to ~350uA, which is enough to run for a whole heating season on 2xAA NiMH hybrid nominally.  (The DS18B20 would also need to be swapped for, say, Mike's preferred thermistor, for the lower supply voltage.)
>> 
>> (I'm using the RTC 1Hz output to sleep more efficiently.)
>> 
>> I'm not suggesting that we apply the mod, but it gives an idea of what is possible.
> 
> Having looked at the schematic, you could put the supply to the DS18B20 onto an io pin, thus giving you power control over the DS18B20.
> 
> Stuart
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