Nuts and Volts - May/June 2018

The first two lines are importing functions from external modules, i.e., they are bringing in capabilities from other Python programs so that we may use these functions in the camera program we are creating. This saves us time and shortens the code we have to write. The next line — camera = PiCamera() — is assigning a name to the PiCamera function that will be used to refer to this function. It’s similar to how one might refer to “Light Amplification by Stimulated Emission of Radiation” as simply “laser” in the sense that we are only assigning a name for the sake of simplification. The lines camera.start_preview() and camera.stop_preview() are functions that turn the camera on and off for you to get a preview of what you are capturing. These are functions that came from the PiCamera function you imported earlier. The line in between — sleep( 10) — tells the camera to wait 10 seconds before executing the next line of code. Again, this was a function you imported from the time module at the beginning of the program. Hopefully, this brief explanation gave a bit more insight into the workings of the code and also showed how friendly it can be to interpret and write Python. One more thing I’ll add that the tutorial did not include. This camera setup is pretty straightforward and should work without a hitch due to its relative simplicity. In most cases, if you believe you’ve done everything correctly, any problems encountered are simple fixes. So, if you run into any problems when you’re trying to capture a still, try the following:

FIGURE 18.

Pi 3 GPIO layout.

supplementary explanations may provide some benefit.

Next is the first code you are instructed to enter into a Python file to run for the camera. Let’s quickly run through the lines:

from picamera import PiCamera
from time import sleep
camera = PiCamera()
camera.start_preview()
sleep(10)
camera.stop_preview()

• Make sure you inserted the ribbon cable properly on both the Pi and the camera. This includes ensuring that the cable is pushed in all the way.

• Some people believe it’s better to insert all the peripherals before you boot your Raspberry Pi.

• Make sure the power supply is sufficient (the red LED is steady), and the Pi is reading the SD card properly (the green LED blinks intermittently).

• If it’s a power issue, try using a different power source; if it’s the SD card, try rewriting it or using a different one.

• Make sure that your Raspberry Pi is updated. The commands for updating and upgrading your Pi are sudo apt-get update followed by sudo apt-get upgrade. (See Extra/Commands for details.)