Servo Controlled Time-Lapse Camera

Introduction: Servo Controlled Time-Lapse Camera

For our HAB mission, we created a servo controlled camera running on a RasPi Zero and using xChips to control/drive a servo.

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Step 1: Things Used in This Project

Hardware components

  • Raspberry Pi Zero x 1
    Get the newer version that has a camera interface. And make sure you got a Micro-USB cable to connect the Pi to your computer
  • XinaBox BR03 x 1
  • XinaBox OC05 - Servo Driver x 1
  • XinaBox XC10 x 1
  • XinaBox MD01 x 1
    Really just a spacer to mount the servo on, so very optional.
  • Raspberry Pi Camera Module x 1
    Remember to get the narrower flat cable that fits the RasPi Zero
  • 3.7v LiPo battery (generic) x 1
  • Servos (Tower Pro MG996R) x 1
    Any small servo with standard 2.54 mm 3 pin header cable, and mounting gear (nuts/bolts, rubber bands, cable ties, glue, or what ever is your preference)

Software apps and online services

  • Raspberry Pi Raspbian Lite
  • Balena Etcher
  • XinaBox OC05 Servo Driver

Step 2: Story

Using the RasPi Zero with the PIcamera, a Servo and the OC05 Servo Driver/Controller, you can shoot a panning time-lapse video.

Step 3: Preparing the SD Card for the Rasperry Pi Zero

  • Download Raspbian Lite and unzip
  • Download Etcher and install
  • Flash Raspbian Lite to a Micro-SD card using Etcher
  • Open your terminal and go to the root of the SD Card
cd /Volumes/boot
echo 'dtoverlay=dwc2' >> config.txt
touch ssh
echo -n ' modules-load=dwc2,g_ether' >> cmdline.txt

The last 3 lines set up the RasPi Zero (and only the Zero) to be able to network via the USB port. Just verify that the last line has no newline before ' modules...' in cmdline.txt!

  • Eject the SD Card
  • Assemble everything as per this video:
  • Connect USB Cable between your RasPi Zero and your computer.
  • Either use a Mac or install Bonjour to SSH to your RasPi Zero: ssh pi@raspberrypi.local
  • Password is raspberry
  • Finally setup internet sharing on your computer allowing Broadcom Ethernet to connect to your WiFi via your computer.

Step 4: Configuring the Raspberry Pi Zero

sudo raspi-config nonint do_expand_rootfs
sudo raspi-config nonint do_i2c 0
sudo raspi-config nonint do_camera 0
sudo apt-get install vim python-smbus i2c-tools
sudo apt-get install python-picamera python3-picamera
sudo reboot
  • The first 3 lines makes full use of your SD card, activates I2C for the servo controller and activates the PIcamera.
  • Then I2C tools are getting installed and then PIcamera drivers.
  • Then reboot to make the changes take effect.
  • Login again.
  • Test the connection to your servo controller, and if everything is fine you should see this:
pi@raspberrypi:~ $ 
    0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: 70 -- -- -- -- -- -- --

Step 5: Install OC05 Servo Driver

cd ~

git clone https://github.com/xinabox/rpOC05.git</a>
cd rpOC05

sudo python setup.py install

This will install the Servo Driver library, once installed, test by:

cd examples
python simpletest

Step 6: Program

  • Copy and Paste the code below into xservo.py.
  • Create a frames directory
cd ~
mkdir frames
python xservo.py

It should now start taking pictures and store them in frames.

Step 7: Extra Steps

  • You can have the program run automatically by crontab -e
  • And then write at the bottom of the file: @reboot python /home/pi/xservo.py
  • Once your shoot is finished, you can copy the pictures to your computer. I use scp
  • And then I use convert from ImageMagick, like this: convert -quality 100 frames*.jpg outputfile.mpeg

Step 8: Code

servo.py Python

from __future__ import division
import time
from datetime import datetime<br>import rpOC05
import picamera

pwm = rpOC05.PCA9685()

servo_min = 150  # Min pulse length out of 4096
servo_max = 500  # Max pulse length out of 4096
i = servo_max + 10
chan = 8
filename = 'frames/frame-%s.jpg'
pwm.set_pwm_freq(50)
# signal ready with a wave
pwm.set_pwm(chan, 0, servo_min)
time.sleep(1)
pwm.set_pwm(chan, 0, servo_max)
time.sleep(1)

print('Time-Lapse Running...')
while True:
  if i > servo_max:
    i = servo_min

  pwm.set_pwm(chan, 0, i)
  with picamera.PiCamera(resolution=(1920,1080)) as cam:
    ts = str(datetime.utcnow())
    cam.capture(filename % ts,quality=90,thumbnail=None)
  # time-lapse interval in seconds.
  time.sleep(0.1)
  i += 1

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