Page 210 - ARM Based Microcontroller Projects Using MBED

196 8. INTERMEDIATE LEVEL PROJECTS

while(1) // Do forever
{
mV = 3300.0f * ain.read(); // Voltage in mV
gotoscr('4', '0'); // Goto line 4 col 0
MyPC.printf("Voltage = ");
MyPC.printf("%f", mV); // Display voltage
wait(1.0); // Wait 1 second
}
}
FIG. 8.57, CONT’D

FIG. 8.58 Typical output from the program.

8.21 PROJECT 17—ANALOG TEMPERATURE SENSOR
(DIGITAL THERMOMETER)

8.21.1 Description

In this project, the ambient temperature is measured using an analog temperature sensor
chip, and is then displayed on the PC screen every second.

8.21.2 Aim
The aim of this project is to show how the ambient temperature can be measured using a
temperature sensor chip.

8.21.3 Block Diagram

Fig. 8.59 shows the block diagram of the project. In this project, a TMP36-type analog tem-
perature chip is used. This is a low-voltage precision temperature sensor (see Fig. 8.60) having
the following features:

• Voltage input: 2.7V–5.5VDC
•10mV/°C scale factor
• 2°C accuracy over temperature
• 0.5°C linearity
• Operating range: 40°C to +125°C
• Less than 50μA quiescent current