Using an LED strip (of 32 WS2812B individually addressable LEDs) and an MPU6050 gyro/accel, this fidget calculates the position of a rotating pendulum that reacts to acceleration and gravity and simulates the effect of gravity on different bodies in our solar system (including Pluto).
Concept, Design and Idea Copyright (C) 2021, 2022 Kurt Manucredo, under the CREATIVE COMMONS ATTRIBUTION-NONCOMMERCIAL 4.0 INTERNATIONAL PUBLIC LICENSE
For more information on Copyright please refer to the respective files and LICENSE files.
You can travel the following bodies in our solarsystem in order:
- Mercury (0.38g) (white)
- Venus (0.904g) (light blue)
- Earth (1g) (dark blue)
- Mars (0.3794g) (red brown)
- Jupiter (2.528g) (white grey)
- Saturn (1.065g) (yellow)
- Uranus (0.886g) (violet)
- Neptune (1.14g) (green)
- Pluto (0.063g) (pink)
To travel from planet to planet hold the fidget horizontally, turn it
twice by 180 degrees. If there is no change, try doing it faster.
To turn the fidget on, turn the upper half clockwise. To turn it off, turn the upper half counter-clockwise.
- 1x Arduino Nano or compatible
- 1x MPU6050 breakout board
- 1x 5 Volts Voltage-Step-Up-Booster 0.9-5 Volts
- 1x strip of 32 WS2812B individually addressable LEDs (*)
- 1x 4-pin 6x6x5 push button, 0.4mm push distance
- 1x 3d-printed models of the fidget (**)
- 3x 0.6x6.5x10 mm compressing spring
- 3x M3 DIN 9021 washer
- single wire 0.5mm diameter
- and a punch of cables one can salvage from old LAN cables or similar.
(*): Use a strip with an LED density of 144 LEDs per metre.
(**): all two parts can be found as .3mf files in the design-solarfidget/3mf folder and can be imported directly into the 3d slicer software. If you need to make changes to accommodate your own hardware, use the solarfidget-aaa.scad file to do so.
Pic. 1: The two parts pictured above compose the solarfidget
After printing the parts, let them cool down all the way.
Next, carefully try to close the two parts and turn one part left and right slowly. If you notice too much resistance open them again and use sanding paper to sand down the locking towers. Always sand them down just a little and then try again. If you sand them down too much the whole mechanism may get too loose. If you sand them down too little it might get impossible to unlock and open them again.
I've set the towers so that practically no sanding is required. Only some force is required to repeatedly close, lock, unlock and open them again, until the process works without much force. But every material is different. Even one PLA material may differ from another PLA material.
I printed the parts with a PRUSA i3 MKR3s printer, used the PrusaSlicer 2.4.0 software, selected 0.20mm QUALITY print settings with 30% infill and used a transparent PLA material. I printed the two parts all in one go. It took about 4 hours.
I recommend transparent PLA material. White PLA works, too. The light, however, will not be as bright. Any other colour will only let through that colour and make it impossible to distinguish between planets.
Using another material than PLA will likely result in slightly different dimensions and the electronics being loose or too tight to fit. The fit for the MPU6050 is particularity crucial and should be very tight to hold it in place perfectly.
If you need to make changes to the parts, use the solarfidget-aaa.scad file to do so. At the beginning of the file, change the dimensions of the electronic parts, then further down, in the file, adjust the placements for those parts so that they don't overlap. The electronic parts positions can be altered in the module named electronics. If you intend to change the amount of LEDs, remember, you can only change the amount by a multiple of 4.
First, remove the USB plug from the module.
Next, we need to shorten the module a bit.
Pic. 2: Cut away as much as possible. But don't cut off the USB solder
spots.
Pic. 3: Grind down until short enough.
Then remove the remaining tin-solder and remains of the USB plug.
Pic. 4: We need to get rid of those four dips on the underside of the
module.
Pic. 5: That's what we want! All clean now.
Cut two pieces of 0.5 diameter blank wire to the right length and insert them, one on each side of the batteries compartment. One between the Plus (+) and Minus (-), the other between the Minus (-) and Plus (+).
Pic. 6: The wire connects the two poles and connects the batteries
serially
Next, insert two washers into the two Plus (+) poles. Use a M6 key or something with which you can apply force to get it in. I never managed to break the plastic. But if you want to make sure, use your thumb to push against the other side. Don't push a third washer into the last Plus (+) pole. We'll do this later.
Pic. 7: The washers need to sit tight and deep enough to get in contact
with the blank wire.
Next, insert two compressing springs into the Minus (-) poles. This might be a bit tricky. Again, don't insert the third spring, we'll do this later.
Pic. 8: The springs need to sit tight and deep enough to get in contact
with the blank wire.
Before we can continue with the rest, we put the Voltage Booster Module in its right place.
Pic. 9: That looks nice!
Use a short 0.5 diameter single wire and strip it on both sides. One shorter, the other longer. Now, place the longer blank wire into the last Minus (-) pole and push the last spring in there.
Now, take the push button and solder that wire with the shorter blank end onto one of the terminals, so the circuit will only close if the button is pushed. Use another wire, solder it to the other terminal and then onto the -In of the Voltage Booster Module. Then push the button into its proper place and make sure its level with the quadratic plastic end.
Pic. 10: There, last spring installed and wire soldered on. Solder it on
before you push the button in it's place.
Pic. 11: This is the other side. The green cable goes to the -In of
the Voltage Booster Module.
Next, we use another wire, strip it again on both sides, one shorter, one longer and insert it into the last Plus (+) pole.
Pic. 12: There! Way to go!
Then route it through the little hole next to the place where the MPU6050 will go. There is place next to the MPU6050, so don't route it over the MPU6050. Push the last washer in and solder the wire to the Voltage Booster Board on its In+ pole.
If this is all done, insert three batteries and test the mechanism. Close the two parts and try out. If you see the Voltage Booster Module light up, congratulations, you've done it.
If not, the fault may be with the button or the contacts of the batteries compartment. Push the washers and springs harder in. Then check the button by pressing it without closing the two parts. Check again with the two parts closed. If it doesn't work, the button may be too deep inside. Put a thin plastic or something hard and thin between the button tower and the button and try to fix it that way.
If it works no matter which way you turn the upper part, when closed, then the button is too high. Try to grind down the button tower to fix it. Although, this might be a difficult task. I recommend altering the button tower in the solarfidget-aaa.scad design file.
If the Voltage Booster Module enables as soon as you install all batteries you soldered the wires to the wrong terminals on the button.
Keep all wires as short as possible. We will solder the wires first onto the MPU6050 and Voltage Booster Module then stick them from below into the Arduino and solder them on from above the Arduino. If the wires are too long, we won't be able to push the Arduino into its place.
Solder a red cable onto the Voltage Booster Module where the boosted voltage will come out.
Pic. 13: There! It's that round spot where the trace leads away to the
resistor.
Next, solder two black cables to In-. Solder one of them to GND on the MPU6050. Leave the other for the Arduino.
Now, solder four cables onto the MPU6050, one onto VIN, one onto SCL, one onto SDA and another onto INT. Keep them short.
Have the red cable stick through VIN and the black cable stick through GND on the Arduino. Have the cables coming from SCL, SDA and INT stick through A5, A4 and D2, respectively.
Now solder them on from above.
Pic. 14: That looks about right. Maybe you can get those cables a bit
shorter. It's a tight fit here, but it works. Fold them in carefully.
Next, find that elliptical hole between the Arduino and the MPU6050. We'll use it to route the cables for the LED strip through it. But first, we'll prepare the LED strip.
Solder three spots onto the 32 addressable LED strip. Note the direction of the arrows on the strip and solder the spots on the right end. If the arrow points to the end of the strip, it's the wrong end.
Pic. 15: Solder the spots onto the back.
Place the LED strip around the inside of the fidget's top part. Start with the centre of the first LED at 9 o'clock and continue clockwise. 9 o'clock is where the elliptical hole is located.
Now, solder a red cable to +5V, a black cable to GND and a different coloured cable to D6 on the Arduino. Now, route them through that elliptical hole. Then solder them to Plus (+), DATA and Minus (-) on the LED strip, respectively; that is, the top most solder spot is Plus (+), the middle one is DATA and the lowest one is Minus (-).
Copy or link the folder in arduino-solarfidget/libraries/solarfidget into
your Arduino/libraries folder.
Place the files at:
https://github.com/jrowberg/i2cdevlib/tree/master/Arduino/I2Cdev
in a subdirectory in your Arduino/libraries folder
Place the files at:
https://github.com/jrowberg/i2cdevlib/tree/master/Arduino/MPU6050
in a subdirectory in your Arduino/libraries folder
Place the files at:
https://github.com/adafruit/Adafruit_NeoPixel
in a subdirectory in your Arduino/libraries folder
Open the Arduino IDE and load the file:
arduino-solarfidget/arduino-solarfidget.ino
Place the fidget on a level surface and connect it to your computer. Open the serial monitor. Compile and upload the programme to the Arduino. Wait for the Arduino to reset and start. Look at the serial monitor and note down the calibration values.
Now, in the file:
arduino-solarfidget/arduino-solarfidget.ino find the following line:
#define SERIAL_DEBUG
Comment out this line so that it looks like this:
//#define SERIAL_DEBUG
Find and uncomment the line:
//#define FIDGET 1
Now, find the lines:
#if (FIDGET == 1)
// Fill in your calibration values here
mpu.setXAccelOffset(0);
mpu.setYAccelOffset(0);
mpu.setZAccelOffset(0);
mpu.setXGyroOffset(0);
mpu.setYGyroOffset(0);
mpu.setZGyroOffset(0);
#endif
and replace the 0 values with the values you just noted down for Gyro and Accel.
Then, comment the following line:
#define AUTO_OFF
We don't want the fidget to turn off the light. If we don't want to play with the fidget, we'll turn it off with the on/off mechanism.
Save the file and upload the programme again.
Finally make sure the LED strip is placed correctly in the fidget and the light of the pendulum is at the right spot. Do this by holding the fidget askew and wait for the pendulum to rest. Now, move the strip either left or right to bring the light into the correct position.
After that, push the Arduino into its place.
Pic. 16: All done. Batteries inserted.
You should all be set now. Have fun travelling our solar system.