Pendulum Challenge Kit product #MSPK01 from the
Maker Shed ( makershed.com/pendulum) has all
the parts needed to make the game, including a pre-programmed PIC microcontroller. Or you can build
the author’s version by using the parts listed below:
Pendulum Challenge printed circuit board (PCB)
Download the layout from makezine.com/26/
pendulum and order through free ExpressPCB
software ( expresspcb.com). You can select the Mini-Board package ( 3 boards for $51 plus shipping).
PIC microcontroller part #PIC16F886-I/SP-ND from
Digi-Key ( digikey.com)
Resonator, ceramic Digi-Key #X909-ND
Piezo buzzer Digi-Key #102-1115-ND
Switch, SPDT slide Digi-Key #450-1598-ND
Switch, SPST pushbutton, green Digi-Key #EG2551-ND
Switch, SPST pushbutton, black Digi-Key #EG1301-ND
LED, green Digi-Key #67-1100-ND
LEDs, red ( 14) Digi-Key #67-1103-ND
IC socket, 28-pin Digi-Key #AE10286-ND
Capacitor, 0.1μF ceramic Digi-Key #BC1148CT-ND
Male header, 6-pin, right-angle Digi-Key WM4104-ND
Coin batteries, AG13 or A76 ( 3)
Paper clips ( 2)
Panel or enclosure at least 3. 8"× 2. 5", to mount PCB
Soldering iron and solder, pliers, wire cutters
Foam tape, double-sided (or hot glue)
Programming cable for PIC chips such as
the PICkit 2, Digi-Key #PG164120-ND, $35
Computer with internet connection and Windows OS
5 incorporate random delays and reversals
to keep you on your toes. At each level, the
player is allowed 15 attempts to hit the target.
If the target is hit, the player advances to the
next level — if not, the game ends.
1. Get a circuit board.
The Pendulum Challenge is built on a custom
2-layer PCB, which you can make yourself
or have manufactured. To design the PCB,
I used the free Windows app ExpressPCB
( expresspcb.com). You can download the PCB
layout in ExpressPCB format at makezine.
com/26/pendulum, along with the Pendulum
Challenge circuit schematic and PIC software.
From ExpressPCB, you can easily price and
order boards from the Layout menu. You’ll
typically receive the bare boards 3–4 days
114 Make: makezine.com/26
2. Solder the components.
Fit the components into their through-holes
as labeled on the board and solder them in
place, making sure to orient the cathode (–)
side of all the LEDs (indicated with a shorter
leg and a flat part on the plastic) through the
holes with the square solder pads.
For the 6-pin programming header at the
top, labeled ICSP (in-circuit serial programming), the best practice is to solder it in.
But for aesthetics, I sometimes leave it
unsoldered. Then I just temporarily plug the
header into its holes whenever I need to
program the chip, and extract it afterward.
I can’t guarantee that this will always work,
but it has for me so far.
3. Make the battery holder.
I couldn’t find a suitable battery holder
to fit the available space on the board, so
I constructed my own using paper clips.
(Optionally, you could use an external AA
battery holder, soldering the black and red
wire leads to appropriate pads on the PCB.)
My paper-clip fabrication is composed of
4 parts: 2 retainers and 2 terminals.
The retainers are U-shaped wires that hold
the batteries in place; to make them, bend
paper-clip wire around a coin cell, run each
end through one of the PCB hole pairs above
and below the battery site, and cut to length
For the terminals, bend 2 shorter V-shaped
wire pieces and insert them into the holes at
each end of the batteries. Solder all 4 parts
onto the circuit board (Figure A).
4. Install the software.
Install the software that comes with your
PICkit programmer, then download the
Pendulum Challenge software from makezine.
com/26/pendulum. You can grab either the
compiled hex image PC1000.hex, which is
ready to upload to the PIC, or the source
code directory if you want to read or modify
and compile the code yourself using PIC
Make sure the power on the PCB is