Input devices

Group assignment

Obhective:

Probe an input device's analog levels and digital signals

Group assignment:Probe LM 35 analog levels

To check the analog levels of input devices we used LM 35 body temprature sensor which was used in my individual assignment.First i studied about the pin configuration of LM 35 and tried to explain to my fab mate.Then i also told them fetures of LM 35 as well.I used atmega 328p board of made by me inthis week and interfaced the LM 35 to it.

Features:

Calibrated directly in ˚ Celsius (Centigrade)

Linear + 10.0 mV/˚C scale factor

0.5˚C accuracy guaranteeable (at +25˚C)

Rated for full −55˚ to +150˚C range

Suitable for remote applications

Low cost due to wafer-level trimming

Operates from 4 to 30 volts

Less than 60 µA current drain

Low self-heating, 0.08˚C in still air

Nonlinearity only ±1⁄4˚C typical

Low impedance output, 0.1 Ω for 1 mA load

Code:

Go to Vikram page to check the code which read sensor data

Observation:In the following video i tried to show you change in voltage levels as temperature with respect to change in voltage levels.So in the first half of video you can see intially LM 35 is tested without having any heating material around it.I have observed the voltage levels on DSO.To measure the voltage level for respective temprature i connect DSO probe to LM 35 and check the corrosponding voltage levels and it was found to be 336V.Then in seconf half of video i kept hot soldering gun near LM 35 sensor to heat up.Then i measure the voltage levels i found on DSO is around 403mV.So change in voltage levels as sensor kept closed to any heating materail that indicate that it wont show the ambient temperature.

We select channel 1 of DSO and connect positive probe to data pin of LM 35 sensor and other probe connected to GND terminal.Then we observed the analog signal on DSO.

Tutorial 2:Probe ultrasonic sensor digital levels

To check the digital levels of input devices we used ultrasonic sensor which was used in Snehal individual assignment.She gave us detailed explanation of ultarsonics sensor such as pin configuration,features and application of it as well.

About Ultrasonic sensor:

An ultrasonic sensor is an instrument that measures the distance to an object using ultrasonic sound waves. An ultrasonic sensor uses a transducer to send and receive ultrasonic pulses that relay back information about an object's proximity(Inc.www.maxbotix.com)

Connection pin out

Vcc of ultrasonic sensor to VCC of Attiny 45

GND of ultrasonic sensor to GND of Attiny 45

Trig of ultrasonic sensor to PB3 of Attiny 45

Echo of ultrasonic sensor to PB4 of Attiny 45

*We used arduino's TX and RX pin and RST connected to GND of arduino for serial communication.

As assignment is to check digital and analog signal ,we have performed this assignment for LM35 and ultrasonic sensor. As ultrasonic sensor sends digital signal ,we have checked this signal using DSO.We have connected ultrasonic trigger and echo pin to my input board.And we connected probe to GND and trigger pin and we get the digital waveform.