Temperature and Pressure Control using the
This project involves the implementation of control and monitor for dual processes. The variables monitored are pressure and temperature. The input control is a 16 button keypad and the output is monitored in a 16 character LCD The device can be widely deployed as a cheap solution to room and automobile climate control automation.
1. Display Pressure or Temperature
20° C and 30° C.
2. Temperature can be controlled to any of the displayable threshold with approximately +/- 2° C control range.
3. When Pressure is selected as LCD output, temperature is monitored every 20 read cycles or approximately 70035 m secs.
4. Pressure change alarm LED is flashed when the increase in pressure is past 5 PSI within five read cycles or approximately 35 m secs.
Hardware: 1 AT90S8535, 1 STK200, 1 RCM2034R LCD,
1 16 button keypad, Lucas NovaSensor NPC 410 pressure sensor,
1 NTC GE 76 thermistor
LCDpin Connection 1 gnd - Port A 2 +5 volts - PortA7 3 trimpot wiper 4 PortD6 5 PortD5 6 PortD4 7-10 no connection 11 PortD0 12 PortD1 13 PortD2 14 PortD3
Keypad pin Connection
Clock rate 4Mhz AREF 4.096 Volts
The following graph depicts the linearization relationship for the GE 76 thermistor:
Temperature^2 VS Resistance
Voltage step per PSI increase for the Lucas Novasensor:
4.1667mv per PSI
DC offset from output of NPC-410
Table of temperature with respective voltage.