I’ve been setting up equipment to start a ProjectAVR YouTube channel for a while. Almost there now. Just a few more pieces of the jigsaw to put in place. In the mean time, I’ve been learning about video editing and sound recording. One piece of equipment I will have need of is a ‘Clapper Board’ or ‘Slate’ to aid syncing of sound and video from multiple sources. I decided to make my own rather then buy one of the many ready made solutions available. After having searched around online though, I found that there aren’t a great deal of DIY designs.
Since I’ll be working on my own, I won’t need the usual panel that notes are written on, all I need is the visual/audio que. I first made up a circuit with an Arduino Uno and breadboard. It simply traps a keypress and when released gives a 50ms pip and pulses an LED.
Once I had the code working I begun to think about how I would build it. Using an ATMEGA328 for this purpose is like using a sledgehammer to crack a walnut so I decided to use an ATTiny85 Digispark clone I’d got on eBay. I used a small piece of strip board to mount the Digispark clone and other components.
I built the prototype to be powered specifically by cheap ‘Poundland’ USB Powerbanks, of which I have a few. These powerbanks are great value at GBP1 each but any USB socket will power the clapper successfully.
There is one small issue with the ATTiny85 Digispark clone. Since it uses the Micronucleus bootloader for programming via USB, the reset pin has been disabled. The ATTiny’s fuses are set to use the pin as GPIO instead, therefore the board cannot be programmed by ICSP and consequently any code running on the device is subject to 5 seconds startup delay. The next step is to enable the reset pin once more and program the clapper code via ICSP. This will mean that the device will start up and run the code immediately. In the interim, I have added a short audio chirp to signify the device is ready to use. This has proved adequate for now although I may leave the chirp in after enabling the reset pin anyway.
Proving boards have been ordered from my favorite fabricator, Hackvana.com. Later, I’d like to produce a design to acommodate a vanilla ATTiny85 as well. This will require a different programming procedure and a means to connect the hardware. As per normal, once I have finished the design and proved it can be programmed successfully, I will publish a full set of KiCad/Gerber design files along with the code to drive it.