Hardware

GPIO Configuration

GPIO pin assignments for the button and motion sensor can be changed in the pawvision_settings.json configuration file. Update the following fields to match your wiring:

• button_pin: GPIO pin number for the button
• motion_sensor_pin: GPIO pin number for the motion sensor
• motion_sensor_enabled: Set to true to enable motion sensor support

Refer to your board’s pinout diagram to select the correct GPIO numbers.

Required Components

• Single Board Computer (e.g., Raspberry Pi)
• Push Button (momentary switch)
• Motion Sensor (PIR sensor, e.g., HC-SR501)
• Jumper wires
• Breadboard (optional, for prototyping)

Wiring the Button

1. Connect one leg of the button to the designated GPIO pin (see your configuration, e.g., button_pin).
2. Connect the other leg to a ground (GND) pin on the SBC.
3. The software uses an internal pull-up resistor, so no external resistor is required.

Example (Raspberry Pi):

• Button leg 1 → GPIO17 (physical pin 11)
• Button leg 2 → GND (physical pin 6)

Wiring the Motion Sensor

1. Connect the VCC pin of the PIR sensor to a 3.3V or 5V power pin (check your sensor’s requirements).
2. Connect the GND pin to a ground pin on the SBC.
3. Connect the OUT pin to the designated GPIO pin (e.g., motion_sensor_pin).

Example (Raspberry Pi):

• VCC → 5V (physical pin 2)
• GND → GND (physical pin 6)
• OUT → GPIO27 (physical pin 13)

Supported Motion Sensors

PawVision supports standard PIR (Passive Infrared) motion sensors, such as the HC-SR501. These sensors detect movement by measuring changes in infrared radiation.

mmWave Sensors

mmWave (millimeter wave) sensors are also supported for motion detection. These sensors use radio waves to detect movement and offer:

• Higher sensitivity and range
• Ability to detect motion through certain materials (e.g., plastic, glass)
• Less sensitivity to temperature changes and sunlight

To use an mmWave sensor:

• Choose a module with a digital output compatible with your SBC’s GPIO (e.g., IWR6843, RCWL-0516).
• Wire the digital output pin to the configured motion_sensor_pin, similar to a PIR sensor.
• Ensure the sensor’s voltage levels match your board’s GPIO requirements (use a level shifter or voltage divider if needed).

Most modules with a simple HIGH/LOW output will work out of the box. If your sensor requires special handling, you may need to adjust the configuration or code accordingly.

Notes

• Double-check your wiring before powering on the SBC.
• Update your configuration file (pawvision_settings.json) with the correct GPIO pin numbers.
• For permanent installations, consider soldering connections or using reliable connectors.

Safety Advice: Resistors and Voltage Protection

For most basic setups, no extra diodes or resistors are strictly required. However, for added safety and reliability:

• Button:
  • You may add a small resistor (330Ω–1kΩ) in series with the GPIO pin to limit current in case of accidental shorts.
  • Hardware debounce (capacitor + resistor) is optional; software debounce is already implemented.
• Motion Sensor:
  • If your PIR sensor operates at 5V and your SBC GPIO is 3.3V tolerant, add a voltage divider (two resistors) or a logic level shifter to protect the GPIO pin.
  • A small series resistor (330Ω–1kΩ) can also help protect the pin.
• Diodes:
  • Not required for basic button or PIR sensor wiring.
  • Use a diode only if you expect possible reverse voltage or inductive loads (not typical for these components).

Summary:

• For most users, no extra diodes or resistors are strictly required.
• Adding a small series resistor (330Ω–1kΩ) to each GPIO input is a good precaution.
• Use a voltage divider or level shifter if your sensor output is 5V and your board’s GPIO is 3.3V.