[Weather] The Tini Weather Server and Solar detection

[Mark Richards]

Erik Retvedt wrote:
> Has anyone used the Humidity/Temp/Solar [HTS3-R1-A] from Hobby Boards 
> with Tini. Humidity and Temp is working perfect, but I have searched 
> internet for information regarding implementing Solar Radiation on the 
> TWS. Is there a OneWireContainer or do I have to use one and modify it.
> 
You will be reading the DS2438 vSens voltage and converting this into a 
light intensity value.  I don't use the java library so can't tell you 
which function reads vSens.

The 2438 has an internally-connected A/D that reads vcc, an external 
0-10v A/D which in this case is used for the humidity sensor.  This 
leaves the "current sense" input (+/- 0.125v).  I haven't seen the 
circuit, but suspect it's a reverse-biased diode in series with a shunt 
resistor across the current sense terminals.

I've found a number of problems with this technique if you want to 
emulate a solar radiometer, not the least of which is the response curve 
of the diode itself.  However, if you want and indicator that says "it's 
daylight", it will work fine.

/m