Plant Moisture Alarm – Custom PCB Embedded System
Plant Moisture Alarm – Custom PCB Embedded System
Embedded Files
Designed and fabricated a custom PCB-based plant moisture monitoring system using an ATtiny45 microcontroller. The system measures soil resistance and drives multi-state LED indicators to communicate moisture levels in real time.
Designed and fabricated a custom PCB-based plant moisture monitoring system using an ATtiny45 microcontroller. The system measures soil resistance and drives multi-state LED indicators to communicate moisture levels in real time.
This project involved the full design cycle of an embedded hardware system, including schematic capture, PCB layout, fabrication, assembly, enclosure design, and system testing.
The system measures soil moisture indirectly through resistive probes connected to an analog input on an ATtiny45 microcontroller. Based on measured voltage thresholds, the firmware drives three LED indicators:
Green – Soil moisture sufficient
Yellow – Marginal moisture
Red – Dry soil (watering required)
Hardware Design
Designed schematic and component selection (ATtiny45, LM7805 regulator, LED drivers)
Created custom PCB layout with power regulation and decoupling
Implemented voltage divider sensing circuit for analog measurement
Generated fabrication files and assembled the board manually
Enclosure & Integration
Enclosure & Integration
Designed custom 3D enclosure in Fusion 360
Integrated PCB and battery housing
Created viewing window for LED indicators
Testing & Results
During testing, the system powered on successfully and responded to probe input., The red LED activated, indicating the measured analog voltage remained below threshold.
This debugging process highlighted:
Importance of sensor calibration
Analog signal conditioning challenges
Firmware threshold tuning
Need for PCB test points
Phase-Locked Loop (PLL) Design
Phase-Locked Loop (PLL) Design
Designed and experimentally characterized a Phase-Locked Loop (PLL) using the CD4046 IC to analyze lock range, capture range, VCO linearity, and loop filter behavior. Evaluated system-level tradeoffs between stability, bandwidth, and ripple under varying filter configurations.
Designed and experimentally characterized a Phase-Locked Loop (PLL) using the CD4046 IC to analyze lock range, capture range, VCO linearity, and loop filter behavior. Evaluated system-level tradeoffs between stability, bandwidth, and ripple under varying filter configurations.
This project focused on the design and experimental analysis of a Phase-Locked Loop (PLL) using the CD4046 IC. The system consists of:
Phase detector
Loop filter
Voltage-Controlled Oscillator (VCO)
The PLL synchronizes its output frequency to an input reference signal through closed-loop feedback.
The objective was to characterize
VCO voltage-to-frequency behavior
Lock range
Capture range
Ripple effects
Influence of loop filter cutoff frequency
Key results:
VCO range: 7.7 kHz – 13.8 kHz
Lock range: ~5.5 kHz
Capture range: ~7–11 kHz
VCO gain: ~327 Hz/V
By varying loop filter cutoff frequency (105 Hz → 10.1 kHz), I observed the expected tradeoff:
Higher bandwidth → larger capture range
Higher bandwidth → increased ripple
This project strengthened my understanding of mixed-signal systems, feedback control, and frequency-domain behavior in practical circuits.
Digital Temperature Measurement System
Digital Temperature Measurement System
Developed an embedded temperature measurement system using the AVR128DB48’s 12-bit ADC and an MCP9700A analog temperature sensor, converting raw ADC data into calibrated Celsius readings displayed in real time.
Developed an embedded temperature measurement system using the AVR128DB48’s 12-bit ADC and an MCP9700A analog temperature sensor, converting raw ADC data into calibrated Celsius readings displayed in real time.
This project involved configuring and using the AVR128DB48’s built-in 12-bit successive approximation ADC to measure real-world analog voltages and convert them into accurate digital temperature readings.
This project involved configuring and using the AVR128DB48’s built-in 12-bit successive approximation ADC to measure real-world analog voltages and convert them into accurate digital temperature readings.
System Features
System Features
Configured ADC in single conversion mode
Used internal 2.5V voltage reference for stable measurements
Polled ADC completion flags at register level
Converted 12-bit binary output into hexadecimal and decimal formats
Implemented binary-to-BCD conversion for LCD display
Interfaced MCP9700A temperature sensor for real-time temperature measurement
Fire Protection System for 3D Printers (In Development)
Fire Protection System for 3D Printers (In Development)
Designing a multi-sensor fire detection and automatic power shutoff system for 3D printers using the AVR128DB48 microcontroller, integrating temperature, gas sensing, logging, and relay-based power isolation.
Designing a multi-sensor fire detection and automatic power shutoff system for 3D printers using the AVR128DB48 microcontroller, integrating temperature, gas sensing, logging, and relay-based power isolation.
This project focuses on developing a hardware-based fire protection system designed specifically for unattended 3D printer operation.
The system operates from a 120Vrms wall outlet and monitors environmental conditions in real time using multiple sensors. If abnormal heat or combustible gas levels are detected, the system immediately cuts power to the printer and triggers visual and audible alerts.
System Architecture
System Architecture
The device includes:
AVR128DB48 microcontroller for system control
AFR Fire Protection for 3D prin…NTC thermistor (10kΩ) for temperature monitoring
AFR Fire Protection for 3D prin…TGS2600 gas sensor for smoke/combustible gas detection
AFR Fire Protection for 3D prin…Relay-based 120V power cutoff
Real-Time Clock (DS3231) for time-stamped logging
AFR Fire Protection for 3D prin…MicroSD storage for alert history
LCD interface and buzzer for status feedback
The system uses dual-sensor confirmation logic to reduce false positives before triggering shutdown.
Page updated
Google Sites
Report abuse