Overview

This runs a .NET application which takes pictures via the Raspberry Pi camera and serves them via a WebApi. It also will position the camera based on two servos and a 3d printed pan / tilt arm.

IMPORTANT: This DOES NOT have any authentication on it, so do not put it on a public network.

Prerequisites

• Camera enabled via rasp-config
  • sudo raspi-config
  • Should be the option under interfaces
• Setup .NET Core 5 on the raspberry pi for the "pi" linux user
• Build and transfer the build output to the raspberry pi
• Optionally, install as a service. (Check the paths in camera.service and modify as appropriate)
  • Here's a good tutorial on that: https://learn.sparkfun.com/tutorials/how-to-run-a-raspberry-pi-program-on-startup#method-3-systemd
  • I included a sample .service file that can go in /etc/systemd/system/multi-user.target.wants/ on Raspbian assuming everything is installed in the same paths
  • I suggest try to run it by itself first to make sure everything is set up right, then later run it as a service. Make sure to check with journalctl to ensure the service starts up right.

Prerequisites Pan / Tilt Arm

• 3D Print https://www.thingiverse.com/thing:4710301
• These are the PCA9685 boards I'm using: https://www.amazon.com/gp/product/B07WS5XY63
• These are the servos I'm using: https://www.amazon.com/gp/product/B07L2SF3R4

Other PCA9685 boards and servos will likely work, but would need parameters tweaked in the appsettings.json according to device specifications.

Obtaining the Image

Visit http://pi-ip-address:5000/camera to see the latest snapshot from the camera.

The interval at which it takes pictures is defined via the application settings. Take a look in there if you wish to modify.

Camera

• Interval - The interval between picture snaps.
• Timeout - Amount of time before a picture is considered timed out.
• Width - The width of the captured image. 0 = Maximum Width
• Height - The height of the captured image. 0 = Maximum Height

Using the Servo to Position the Camera

Post to http://pi-ip-address:5000/position

{
  "panAngle": ANGLE_GOES_HERE,
  "tiltAngle": ANGLE_GOES_HERE
}

Tilt angle can be between 30 to 150 degress with 90 being dead on center. Pan angle can be 0 - 180 degress where 90 degrees is looking straight forward. I ran the program set both servos to 90 and hooked up the pan / tilt arm so things were pointing straight forward.

To get the current position you can do a get request. However, this is just reading the value that's been set on the PWM board. This is not actively sensing the position of the servo.

TODO

• Setup is a bit manual, should make it easier to install.
• Would be nice to run in a docker container, but the Pi library I'm using to perform the camera capture is calling raspberry pi camera commandline app to get the captures.
• Current library for the camera is SLOW, need to use something better
  • This is an option https://github.com/techyian/MMALSharp