Smart Camera Development with PIR Detection, IR Illumination, ESP32 & .NET MAUI

A client approached Adequate Infosoft to develop a custom battery powered outdoor camera for remote surveillance and wildlife monitoring applications.

The challenge was to design an ultra-low power smart camera, able to detect motion up to 30 meters away using PIR sensors, able to capture clear images at night using IR illumination, and operate for months on a single battery charge.

The client had tried a number of off-the-shelf security cameras before, but most only had an 8-12 meter PIR detection range and used far too much power to be used long-term outdoors.

We have our own firmware, hardware and PCB design team that created a custom ESP32-S3 based camera solution optimized for low power operation, robust long range motion detection and smart event triggering with minimal false alarms.

1. Long-Range PIR Design

Standard PIR sensors (e.g., HC-SR501) cannot reach 30m reliably. I designed a custom analog front end:

Result: Reliable detection of a walking person at 32m (tested in open field, 25°C ambient).

2. Extended Battery Life with Intelligent Power Management

• Two 18650 Lithium-Ion Batteries (3400 mAh each connected in series with nominal voltage 7.4 Volts)
• Power Management IC is TPS62740 with a load switch TPS22860
• Deep sleep current consumption is 8 µA with PIR and MCU in sleep
• Wake up time from PIR interrupt = 3 ms
• The active current consumption is 240 mA for JPEG capture and storage of each trigger including Camera and IR Led's for approximately 1.8 seconds
• Estimated Battery Life at 10 Triggers per day = 11 months

3. Camera & IR Illumination

Camera and illumination for infrared:

• Camera : OV-2640 (2 Mega Pixels, JPEG out and Programmable Resolution)
• IR radiation : 6 x 850 nm [100mA at 200ms] [20m Illumination]
• Lens : IR-corrected (Eliminates Focus Shift at Night)

The sequence of events for capturing an image:

• A PIR detector triggers the MCU into an awake state (Active state of MCU)
• Camera Power Up (Settling time of 100 ms)
• Image Capture [1600 x 1200, JPEG, size approx' 200 KB]
• Store in MicroSD (FAT32)
• IR LEDs will be turned on only when the lux level [ambient] < 10 (Photodiode [located inside the window])
• Go back to sleep mode (Total Active Time < or = 2 seconds)

4. Firmware Behavior

Written in ESP-IDF (ESP32-S3, because of ultra-low-power ULP coprocessor):

Challenges Overcome

• Schematic Designs and PCB Layouts - Two Layer (JLCPCB Assembly)
• Bill of Materials (BOM) with substitutions for out of stock material options
• Firmware Source Code (ESP IDF - Fully Documented)
• Calibration Procedures (PIR Sensitivity Adjustments and Lens Focusing)
• Test Report provided showing 30m range proof, battery life calculation and trigger rate not greater than 1/day (False Trigger Rate)

The customer placed 50 units in service for monitoring animals in the field for 8 months before the initial battery replacement took place at 10 months of operation.

The passive infrared (PIR) sensors consistently reported a distance greater than 28 meters to detect motion, and the infrared (IR) sensors captured clear images of predator animals as far away as 20m and able to determine unique characteristics of those animals.