Introduction: Laser Tripwire Using ARM Cortex-M4

About: I'm Electrical Engineering Student, Coffee Lover, Automated System designer, Programmer and Security System Designer.

This is a breadboard based project which uses ARM Cortex-M4 (Texas Instruments EK-TM4C123GXL) to make a Laser Tripwire system.The system works with buzzer, external monochromatic light source in the form of focused ray, LDR and a NPN transistor.

BC547 is used as NPN transistor to regulate the output obtained from LDR to ARM Cortex-M4 (Texas Instruments EK-TM4C123GXL). The sensitivity of the system can be modified by changing the configuration of BJT.

The output can be obtained on Serial Monitor of Energia IDE, Tera Team, Keil uVision or any other terminal software. The whole circuit is powered by +5V (VBUS) and +3.3V of EK-TM4C123GXL.

.bin file of c99 code is attached with the provided link at the end of this tutorial. .bin file can be uploaded to the microcontroller using LM Flash Programmer.

Step 1: Requirements

The following things are required to get this project done:

1- Texas Instruments EK-TM4C123GXL
2- Monochromatic Light Source

3- Buzzer

4- LDR

5- NPN BJT (BC547)

6- LM Flash Programmer (software on PC)

7- Virtual Terminal (software on PC)

=> If you don't know how to use and install LM Flash Programmer, then please check out my previous Instructable, or click on the following links:

Downloading LM Flash Programmer

Upload .bin or .hex File Using LM Flash Programmer

Step 2: Pin-outs & Wiring

The Pin-outs & Wiring of ARM Cortex-M4 (Texas Instruments EK-TM4C123GXL) and other peripherals is attached with this step and also given following:

TM4C123GXL => Buzzer


PB0 => VCC



TM4C123GXL => BC547


+5V => Collector

PB5 => Emitter


BC547 => LDR


Base => Pin-1




+5V => Pin-2

Step 3: Upload the .bin File

Upload the attached .bin file with this step to ARM Cortex-M4 (Texas Instruments EK-TM4C123GXL) using LM Flash Programmer.

Step 4: Get Your Output

After uploading .bin file to ARM Cortex-M4 (Texas Instruments EK-TM4C123GXL), you can get your on buzzer or any of your desired terminal e.g. Energia IDE Serial Monitor, Keil uVision and Tera Team Virtual Terminal etc or both.