DMP Photo Booth: The Trigger

After several days of trying to make sense of the POSIX Terminal Interface, I’ve come to a lull in development. Today I’ve been looking through the code, fixing problems as I find them. One major problem I noticed: there is no documentation on the actual trigger.

I decided to draw a schematic for the trigger:

Trigger Schematic

The Concept

It’s pretty basic: a button and 5 lights. My general concept for the trigger was inspired by the starting light at a race. It counts down from 5: at 5, the top light is lit, at 4 the top two are lit and so on. As the count reaches 1, all lights are lit and the camera module calls capture(), starting the race.

If an error needs to be displayed, the 5 lights act as the first 5 bits in a byte (it can display 0 – 31). The lights flash a binary number indicating the error that occurred. Practically, what will happen is a user will go tell a grownup that “it’s blinking”. But an operator can see the code and interpret the problem. The codes will be high level; actual error messages will get printed to the console. However, I felt it important to give negative feedback on the trigger so users don’t just sit there wondering why nothing is happening.

Room for Improvement

There are two things up for consideration at the moment. The first thing is the light configuration. I had a racing starting line in mind, but it turns out that the starting line of a race looks like this:

I guess I’m just not much of a racing fan… I may change the lights to match, or I may abandon my metaphor. Either way, this is a low priority issue.

Secondly, I am considering implementing an audio element to this. If I add this, the trigger will play a low-pitched tone on red lights, and a higher pitched tone on green. This will make it more obvious to the user that a countdown is happening. If you’ve ever played Mario Kart, think the noise the light makes at the starting line.

The only reason I haven’t already added this is because I’m concerned it may be annoying.

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