This is what the play time counter looks inside it’s 3d-printed box. Inside there’s:
- MSP430 value line
- Powertip cheap display
- Piezo buzzer
- Small 3V battery
We have decided to just buy one DS, but we have two kids. When we’re in the car, there’s a constant question of when the ‘swap time’ is. So that we don’t have to keep track of time ourselves, I made a watch that counts down from 10 minutes and then plays a sound. It uses a Powertip PE9665ARF-001 display to show the remaining time, and an MSP430 value line MSP430G2452 MCU.
It’s of course silly to make something like this, but it’s fun.
The PE9665ARF-001 display is really cheap (only a few dollars) and uses a Sitronix ST7576i I2C driver. It’s a really nice display and works brilliantly. Most importantly it’s super cheap, much cheaper than the other displays from Sparkfun or similar. I’ve bought it from Arrow.
I’ll post a picture later when I’ve put it in a box, but the following is a picture of two prototypes, one on a breadboard and one on a prototype board (this is the one I’m going to print a case for).
I got the idea that it’d be fun to make an IR driven toy gun, and sensors that you can put on your body. Then make 10 of them and run around shooting each other. There are several commercial versions of these devices, and its quite a common team building exercise for companies. But it should be easy to make something like this DIY.
So I designed a simple circuit based on the MSP430 value line using the TI Launchpad. It’s a cheap MCU that’s relatively easy to program. Maybe not as easy as Arduino, but much cheaper.
But then I started wondering about the ‘moral’ implications of this. I don’t really want my kids running around shooting each other. I’m not the kind of father who wants to buy gun toys for my children. But is it OK to make it? It sure is fun, but is it right? I’ve got a working prototype of it, but I’m not sure I’m going to proceed making it. I was planning on printing the gun itself on my plastic printer. Maybe I could find some alternative, less agressive angle to the project. But I’m not quite sure what it should be. I certainly could make it look different from a gun, but would that help?
I’ve got C-code for the MSP430 that receives coded IR signals and plays the buzzer. When the button/trigger is pressed, it sends out a coded C signal and plays a short lower tone. The pipe is used to concentrate the IR light, and seems to work ok. The IR receiver is from Sparkfun, and works REALLY well. But it’s a bit expensive, so I’ve ordered some cheaper ones to try out. I’ve only tried it indoors. I guess it might not work outdoors.
Note: I’ve now also tried it with the IR RX Vishnay TSOP31238, which also works well. It’s a through-hole component and costs a couple of dollars. You need a pull-up resistor on it, and preferably an extra capacitor + resistor to filter the power.
Below is a picture of the components soldered together. I haven’t actually made the gun itself yet, due to my doubts about the correctness of making toy guns that lead to quite realistic killing games.
Before setting up the Prusa/Gen7/Teacup printer with an extruder… I put a pen on it and printed. It’s running at 8000 mm/minute and I can run it at 13000 mm/minute without a problem. Really fast. Of course, while printing plastic I can’t do it that fast.
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