Temperature Text Message Alert System Travis Midthun Dr. Stanislaw Legowski Department of Electrical and Computer Engineering

Overview Used to record the temperature in fridges, freezers, next to water pipes, or in boiler rooms If the temperature of the environment leaves the preprogrammed temperature range an alert text message will be sent to the user The user at any time can send a command to the device to receive a temperature reading

Purpose Notify the user that the recorded temperature of the environment has gone outside the programmed temperature range Fully operational from the user’s cellular phone Ability of two way communication between the user and device at any time A practical device that can be easily used in households

Block Diagram

Microcontroller Arduino Uno Uses the ATmega328 microcontroller 14 digital pins, 6 analog pins 32k Flash memory 16Mhz clock Output of 3.3 V Ease of use with GSM Module

GSM Module SM5100B with Cellular Shield Powered through 5V pin Overall low power consumption Idle Mode: < 7.0 mA Communication mode: 2A spikes during transmission and reception of text messages

Temperature Sensor TMP102 I2C digital sensor 12 bit, ᵒC resolution 1.4 V to 3.6 V supply range Accuracy of ±.5 ᵒC or ±.9 ᵒF Can operate from -40 ᵒF to 257 ᵒF 10 µA operating current Very small and low power consumption

Other Components SIM card AT&T GoPhone Quad-band Antenna 880 to 9600 MHz Rechargeable batteries Able to provide 5V/2A Project Box Protective housing

Design Process Make sure components work properly TMP102 Temperature Sensor GSM Module Wire components together on breadboard Create program flow chart Start writing the code for the device Testing and debugging of device House the device in project box for protection

Circuit Diagram

Main Program Flow Chart

GSM AT Commands AT+SBAND = 7 Tells GSM Module which network frequency to use Frequencies: GSM 850 and PCS 1900 AT+CMGF=1 Sets the GSM module into text mode AT+CNMI=3,3,0,0 This will send the content of the text message to the serial port AT+CMGD=1,4 Deletes all of the text message from the SIM card

Main Program Code

Main Program Flow Chart

Receiving a Temperature Reading float getTemperature() { Wire.requestFrom(tmp102Address,2); byte MSB = Wire.read(); byte LSB = Wire.read(); int TemperatureSum = ((MSB > 4; float celcius = TemperatureSum*0.0625; float fahrenheit = (celcius * 1.8) + 32; return fahrenheit; }

Sending a text message AT+CMGS=“XXXXXXXXXX” GSM Module will now expect the content of the message Send the content of the text message through the serial port to the GSM Module The GSM module will now expect a CTRL-Z command that will end the message content

Operation User has received a notification text message that the system has been powered on User has sent the “temp” command to the device The device has responded with the current temperature reading

Operation Notification text from device The recorded temperature was outside of the programmed range, an alert message was sent to the user User is still able to ask for a temperature reading at any time

Operation Alert message from the device was sent to the user User sent the “clr” command to the device The temperature was still outside of the programmed temperature range, so another alert message was sent

Finished Prototype

Future Work Ability for user to add or change phone numbers that the alerts will be sent to Ability for the user to program the temperature range through text messages Power Supply Cut the cost of the device