emeka-io/environmental-monitoring-system

This is a two phase embedded systems project that builds a real time environmental monitoring device using an Arduino Uno, a DHT11 temperature and humidity sensor, and a 1.3 inch OLED display with an SH1106 driver chip. In Phase 1, the project established basic sensor reading and live display. The DHT11 reads temperature and humidity every two seconds, matching its physical sampling limit, and the Arduino processes and displays those values on the OLED screen over I2C, a two wire protocol for connecting a microcontroller to peripheral devices. A major challenge was memory: the initial code used 92 percent of the Arduino Uno's limited RAM due to full frame display buffering. The fix was Page Buffer Mode, a rendering approach where the screen draws in small horizontal sections incrementally rather than holding an entire frame in memory at once. Phase 2 turned the display into a responsive safety system. The firmware evaluates sensor readings against programmed thresholds and triggers alerts when conditions go out of range: an RGB LED switches from solid green to flashing red, and an active buzzer pulses every 150 milliseconds to produce an urgent alarm effect. The OLED dashboard continues showing live readings and adds a warning message identifying which threshold was exceeded, so the user can watch values recover in real time. A key technical achievement was replacing blocking delay calls with non blocking timing using millis, which lets the buzzer, LED, OLED refresh, and sensor polling all run concurrently without any task freezing the others. The firmware is written in C++ and includes a full electrical schematic and wiring diagrams so the build can be reproduced from a breadboard prototype. The full README is longer than what was shown.