Arduino sketches that control sensors for a Capstone project
The Camera sketch is all contained in the OV5642_Sensor.ino file. This controller uses an Arduino Uno board, an ArduCAM Mini 5MP Plus OV5642, and a Catalex MicroSD Card Adapter. The board layout is as follows:
| OV5642 | MicroSD Adapter | Arduino Pin | Details |
|---|---|---|---|
| CS | N/A | 9 | SPI Slave Chip Select Input |
| N/A | CS | 10 | SPI Slave Chip Select Input |
| SCLK | SCK | 13 | SPI Serial Clock |
| MOSI | MOSI | 11 | SPI Master Output Slave Input |
| MISO | MISO | 12 | SPI Master Input Slave Output |
| SDA | N/A | (I2C) SDA | Two-Wire Serial Interface Data I/O |
| SCL | N/A | (I2C) SCL | Two-Wire Serial Interface Clock |
| +5V | VCC | 5V | 5V Power Supply |
| GND | GND | GND | Common Ground |
The MG811 (CO2 sensor) sketch is all contained in the MG811_Sensor.ino file. This controller uses an inland Arduino Uno board, a DFRobot Gravity: Analog CO2 Arduino Compatable Sensor, and a Catalex MicroSD Card Adapter. The board layout is as follows:
| MG811 Sensor | MicroSD Adapter | Arduino Pin | Details |
|---|---|---|---|
| N/A | CS | 10 | SPI Slave Chip Select Input |
| N/A | SCK | 13 | SPI Slave Chip Select Input |
| N/A | MOSI | 11 | SPI Master Output Slave Input |
| N/A | MISO | 12 | SPI Master Input Slave Output |
| VCC | VCC | 5V | 5V Power Supply |
| GND | GND | GND | Common Ground |
| OUT | N/A | A1 | Analog In |
| D | N/A | 2 | Digital In |
The light dimmer is a custom configured circuit paired with a photocell with a 10K pull down resistor and a Keyestudio PIR Motion Sensor. The full sketch can be found in the Light_Dimmer.ino file. The custom circuit uses phase cutting by firing a triac. The triac is opened for a fixed time, effectively allowing only a portion of the AC sinus wave through to the resistive load (LED light bulb).
Below is a table of how readings are measured by the photocell. Calculations were made using Ohm's Law:
| Description | Lux | LDR (Light Dependent Resistor) | PDR (Pull Down Resistor) | Total Resistance | V (+3.3) | Current | Voltage Across PDR |
|---|---|---|---|---|---|---|---|
| Dim hallway | 0.1 | 600K | 10K | 610K | 3.3V | 0.005mA | 0.054V |
| Moonlit night | 1 | 70K | 10K | 80K | 3.3V | 0.041mA | 0.413V |
| Dark room | 10 | 10K | 10K | 20K | 3.3V | 0.165mA | 1.650V |
| Dark overcast day \ Bright room | 100 | 1.5K | 10K | 11.5K | 3.3V | 0.287mA | 2.870V |
| Overcast day | 1000 | 300 | 10K | 10.3K | 3.3V | 0.320mA | 3.204V |
In the case of the dimmer, any voltage above 3, the bulb is completely dimmed (off), any voltage above 1.5, the bulb is at half power, and for any other voltage, the bulb is at full power (on). When the motion sensor fires an interrupt and the voltage is between 3 and 1.5, the bulb is held at full power until no motion is detected.