.(34) Similarly Vrei (which gives i

.(34) Similarly Vrei (which gives information on battery status) will be sampled through the same analog input line PB1, if PA0 is now high while PA1 is low.

.(35) The other three analog input lines are not used here, but could be used for other environmental parameters such as ambient temperature and humidity.
.(36) An LED shows the status of the system. The LED is illuminated when measurements are being taken and while data is being transferred between the data acquisition system and the computer.
.(37) Line PA2 capable of sinking 20 mA current is used for directly driving this indicator LED. The status LED is lit when a logic 0 is placed on this line and is turned off by a logic 1.
(38)The SolData pyranometer is the most expensive component of the system, costing about U.S $300.
.(39) The rest of the data acquisition system components cost less than U.S. $60.
.(40) The sensor produces a
(41)transfer interface between the data acquisition system and the computer.
.(42) It is only powered when a computer is connected to the data acquisition system to retrieve the collected data.