tailieunhanh - Practical Arduino Cool Projects for Open Source Hardware- P7

Practical Arduino Cool Projects for Open Source Hardware- P7: A schematic or circuit diagram is a diagram that describes the interconnections in an electrical or electronic device. In the projects presented in Practical Arduino, we’ve taken the approach of providing both a photograph and/or line drawing of the completed device along with a schematic. While learning to read schematics takes a modest investment of your time, it will prove useful time and time again as you develop your projects. With that in mind, we present a quick how-to in this section | CHAPTER 3 TIME-LAPSE CAMERA CONTROLLER Figure 3-2. Schematic for non-camera-specific portion ofthe circuit Instructions Assemble Prototyping Shield Control connections to the camera are made using a pair of reed relays that provide complete electrical isolation between your Arduino and the camera itself. In fact this project has been designed to use the same pins as the first two outputs on the relay board used in the very first project Appliance Remote Control so that if you ve already built that project you can use the same board without modification. That s exactly what we did and the only difference is that rather than wiring the stereo socket directly to the relay outputs we needed to connect it to a pair of headers to plug into the relay you re building a shield specifically for this project you can start by following the instructions for the Appliance Remote Control project in Chapter 2 but only fit the first two relays that are connected to Arduino digital I O lines 5 and 6 along with their matching reverse-biased diodes. Then wire up the stereo socket so that the outer shield connection goes to one terminal on both relays the center ring connection for the focus trigger goes to the other terminal of the relay on digital pin 5 and the tip connection for the shutter trigger goes to the other terminal of the relay on digital pin 6. The result is a stereo socket with one common connection and a pair of independently switched connections that have one link in common. The two relays will then be connected to focus and shutter release respectively in the camera. Connect Camera Shutter Release There are several different methods shown here for controlling the shutter release of your camera and which one you use will depend on the camera itself. 39 CHAPTER 3 TIME-LAPSE CAMERA CONTROLLER Remote Shutter Release Connector If you are exceptionally lucky your camera will have a remote shutter release connector. If this is the case your job .