What will it do?
I am sticking with my original idea. A target for kids
who want to practice shooting a ball/puck. This will
give children...1) something to aim for when practicing a
sport and 2) visual feedback on how they did (e.g. how hard
the shot and whether they hit the target). See my original writeup on how this
Who's done what beforehand?
I have been looking for different projects that have done
similar things. I've heard of a few projects, but I
haven't been able to track them all done. Here's what
I've heard about:
What materials and components will be required?
Where will they come from? How much will it cost?
Here's a list of all parts I will need to complete the
- TO FIGURE OUT IF/WHERE TO BUY
- Eight 6"x6" copper adhesive for sensors
- Home Depot
- Two 1"x2'x2' insulation for
frame and for tile silicon molds ($5 each..10 total)
- One Fiberglass mat and
- AdaFruit Items to Buy
- Circuit Specialists
- RISD Store Items to Buy
What parts and systems will be made?
I am hoping to build this out in many
Tiles: I'll need to make four 6"x6" tiles that
will contain the velostat. They will contain 1/4"
silicon cover (for protection) with two pieces of adhesive
copper and velostat for the sensors with an LED mounted
behind them, which will give students something to aim
Frame: This will have the backing and will be
what everything will be mounted to. The tiles will be
at the center of it all. On the sides there will be
two strips of NeoPixel lights to provide feedback. The
back will have all the electronics and wires.
Additionally, the frame needs to be...
- Solid and strong...it is going to get hit over and over
again by a hard ball/puck (hence having acrylic and/or
- Light...students and teachers need to be able to carry it
Circuit Board (and mount): The
brains! This will be mounted to the back of the
board. Wires will run from the front to the back and
will attach in at the headers.
Stand: I want to make it so this can rest on
the ground. That being the case, I will need to make a
detachable stand that will make the target stand up on it's
own on the ground (and will be able to take a shot from a
ball/pick). To do this, I am thinking of making it out
of composite materials.
What questions need to be answered?
- Which microprocessor should I use?
- Here are the ports I will need to deliver the
- Digital Ports
- Force LED #1 control connection (must be PORT B)
- Force LED #2 control connection (must be PORT B)
- Target LED control connection (must be PORT B)
- Analog Ports
- Top left tile sensor
- Top right tile sensor
- Bottom left tile sensor
- Bottom right tile sensor
- Potentiometer (for setting of difficulty)
- Programming Pins
- FTDI PINS
- Misc PINs
- AREF: For setting the AtoD reference point
- Based on conversations with Shawn, we decided I am
going with ATMEGA328
- How much power do I need? Here is a
on how to power the NeoPixels, which I believe are
the major components needing power. But now I need to do
the math to determine what will need. Here's what
the writeup says...
To estimate power supply needs,
multiply the number of pixels by 20, then
divide the result by 1,000 for the “rule of
thumb” power supply rating in Amps. Or use 60
(instead of 20) if you want to guarantee an
absolute margin of safety for all situations.
NeoPixels × 20 mA ÷ 1,000 = 1.2 Amps minimum
The choice of “overhead” in your power
supply is up to you. Maximum safety and
reliability are achieved with a more
generously-sized power supply, and this is
what we recommend. Most power supplies can
briefly push a little extra current for short periods. Many
contain a thermal fuse and will simply shut
down if overworked. So they may technically work, but
this is the electronics equivalent of abusing
a rental car.
60 NeoPixels × 60 mA ÷
1,000 = 3.6 Amps minimum
In my case, I will have 10 in each force LED
strip and four in the target strip (24 total).
Assuming they may be at their brightest, I will assume
60mA. Here's math...
24 NeoPixels x 60mA / 1000 = 1.4 Apms minimum
In addition to this, the power consumption of
the ATMEGA 328 adds another 7mA (according
to this article).
But now I have a problem...a 9v battery only gives off
500mA so I'd need roughly 3 batteries. I need to dig
into whether this will work.
- Skill Levels: Should I program in
different skill levels that change how hard have to hit
in order to get a good score?
- Based on some conversations with Shawn, we came up
with an easy way to set different levels...a 10k
potentiometer. I then added it to version 2 of
the circuit board. Now I need to fine one and
figure out how to connect it all into the box.
- The Back: How will the stand/back connect and
- I am planning on doing two things...1) setup o-ring
screws into the corner so can tie it off on a goal,
and 2) setup a stand in the back so that it can rest
on the ground.
- Tile Connection: How will I connect the tiles
to the frame?
- I am leaning towards glue. I was worried about
whether the glue would cause problems with the
conductivity, but Shawn doesn't think it will be a big
Here's the plan with a breakdown of the daily goals and work
will need to do...
- Week of 5/12:
- Goal: Get frame and circuit boards designed and
first drafts built
- Plan it all out (aka write this document)
Design Frame and circuit board
Get frame and circuit boards milled out
Buy: epoxy, insulation, resin
- Week of 5/19:
- Goal: Get board stuffed and frame put together
- Monday (AS220):
Validate board design and stuff board
Need all GND and VCC to connect to one
Figure out issues with board and re-mill
it (see area next to ATMEGA328)
Confirm have everything I need to do 1)
composites on back of board (epoxy) on Thursday,
2) copper adhesive
- Tuesday / Wednesday (home):
- Design backing that will fiberglass (so is
Box for circuit board
- Make changes to the boards/design
Get rid of side holes for straps
Move wire holes to more convenient
Move farther away from each other
Shrink so are 5 3/4" x 5 3/4"
- @ Fay
Laser cut box and stand (cardboard
first and then go to wood)
Check size of backing
- @ AS220
- Buy Dragon Skin
<- tried, but they had run out. Will
need to use what have and then buy more
Re-mill molds (out of
- Weekend: Sat/Sun/Mon (home):
Paint the frame
Make silicon part of tile (made
half because had no dragon skin)
Stuff Draft 2
of board <-
stuffed a board and then broke off the traces on
FTDI connection...need to do again
- Week of 5/26:
- Goal: Put it all together
- Monday (home)
Wire LEDs <- did half
- Tuesday (as220)
Mill out another two boards
Get Copper for vinyl
cutting at school
- Wednesday (home):
Stuff Draft 3 of board
- Wire up sensors
- Test program and connections
- Tuesday/Wednesday (school)
Cut out copper pieces for tiles
Cut Velostat so will fit exactly
- Thursday (AS220):
Get help debugging solidering
Get programming of ATMega working
Buy Dragon Skin <- were all
out of Dragon Skin so went with different
- Weekend (home): Put it all together
Wire up the sensors and get them working
Test with old sensor to see if it
gives smaller values (this tests that the
larger copper isn't making it so there's no
Test with old board and new sensor
(see if get other values, and if so, it
suggests that the wiring I did is different
than the first board)
Get analogRefence(External) working
Get all tiles working
Wire up lights
Attach backing to frame
Put eye bolts in
Do final presentation.png slide
- Week of 6/2: Finalize it all
- Goal: Debug and get it all working
How will this be evaluated?
Goal #1: Provide decent visual feedback
When a ball hits the backing, will it show where was hit and
how hard it was hit! If there is visual feedback that
is accurate (e.g. it senses the hit in the right place and
it gives a good indication of how hard it was all hit, then
goal #1 will be satisfied.
Goal #2: Make it versatile and sturdy
Can the target be easily mounted to a goal? Can it
rest alone on the ground? Can it take a hit from a
ball at 50mph? This is the second way in which this
project should be evaluated.
Goal #3: Does it look cool :->?
I'm not the most artistic guy, but I do want to see if I can
make this look pretty cool with different colors, etc.