garden timer help

hello, I would have to implement a project, they intend to achieve a system of automatic control to microcontroller or microprocessor king ***** x irrigation of the park of a villa in the countryside. The latter is divided in 4 areas must be watered in hours and several times the length of time of irrigation is also linked to the temperature Tm of the day, monitored every hour between 7 and 19, as shown in the table below.
Table:
- Tm-less equal to 15 degrees centigrade, the system will not start;
- 15 degrees centigrade lower Tm less-equal 25 degrees Celsius, the times are those listed in the table;
- 25 degrees centigrade lower than Tm-less equal 30 degrees Celsius, the times should be increased by 30%;
- Tm 30 degrees centigrade higher, time should be increased by 50%.

The irrigation system, which is propelled by a pump to draft, still under tension, placed on the bottom of a well of 30 centimeters, send the water to the zones through the opening and closure of 4 valves.
If the water level is lowered until it reaches the level of 2 meters over the ground, the irrigation system must be shut down. This condition is signaled by sending a digital signal from a sensor layer. To capture the temperature using a sensor that gives a voltage output proportional to absolute temperature V = KT = 10 K with millivolt / ^ K