Build Instructions

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• 1

  Step 1

  All schematics for this project are shown above. All the Arduino pin connections are listed below:

  Analog

  0 - Gyroscope Y (Y4.5)
  1 - Potentiometer 1
  2 - Gyroscope X (X4.5)
  3 - Accelerometer Y (YAcc)
  4 - Accelerometer X (XAcc)
  5 - Potentiometer 2

  Digital

  0 - serial in - this must remain unconnected
  1 - serial out - this is hooked up to the MIDI output
  2 - 74HC165 data pin (Q7)
  3 - 74HC165 clock pin (CP)
  4 - 74HC165 latch pin (PL)
  5 - 74HC595 clock pin (SH_CP)
  6 - 74HC595 latch pin (ST_CP)
  7 - 74HC595 data pin (DS)

  no connections to digital pins 8-13

• 2

  Step 2

  Solder LEDs and diodes to sparkfun board, be mindful of their orientation.

  Thread the leads of 16 LEDs (5mm or 3mm are fine, I used 5mm) through LED holes in the Sparkfun PCB. These boards are compatible with 4-lead RGB LEDs, so there are four available holes on each button pad. You can use the two center holes for single color LEDs. Be sure that the flat edge of the LED (the cathode) lines up with the flat marking on the PCB.

  Cut about 1ft of 16 conductor ribbon cable. Separate and strip the ends of all 16 wires on one side and solder to Sparkfun PCB. The following list gives all the colored conductors in order with the name of the PCB hole they should be soldered to, if you do this correctly none of the wires should cross. Note that since I'm only using a single color LED, I'll wire up only the "blue" anode.

  Connections:

  one side of ribbon cable
  Brown SWT-GND1
  Red LED-GND1
  Orange SWT-GND2
  Yellow LED-GND2
  Green SWT-GND3
  Blue LED-GND3
  Purple SWT-GND4
  Grey LED-GND4
  White BLUE4
  Black SWITCH4
  Brown BLUE3
  Red SWITCH3
  Orange BLUE2
  Yellow SWITCH2
  Green BLUE1
  Blue SWITCH1
  other side of ribbon cable

  Use a bench vice to clamp the16 pin socket on the ribbon cable. If you do not have a bench vice do not use pliers do this, you will clamp the socket on sideways and mess up the connections. You're better off using a hammer to tap the clamp shut, just make sure you are always applying pressure evenly across the socket.

  Be sure the clamp the socket on the ribbon cable in the same orientation indicated in the images above.

• 3

  Step 3

  Two 74HC595s (wired in parallel) will be driving all the LEDs in the project as well as providing power to all of the buttons. The 74HC595 is an 8 bit serial in parallel out shift register. I've written a detailed tutorial about multiplexing with the 74HC595, and you can find more info about this chip on its datasheet. Please note that the 74HC595 drawn in the schematic is not a pin diagram, I have rearranged the order of the pins to make the circuit diagram more clear. The pin diagram for the chip is shown in fig 4.

  The 74HC595 has the following pins (the technical name may be one of several things depending on which data sheet you are reading):

  Position /  Common Name / Technical Name

  1 parallel output 2 QB or Q1
  2 parallel output 3 QC or Q2
  3 parallel output 4 QD or Q3
  4 parallel output 5 QE or Q4
  5 parallel output 6 QF or Q5
  6 parallel output 7 QG or Q6
  7 parallel output 8 QH or Q7
  8 ground GND
  9 serial data output QH' or Q7' or Q7S
  10 master reset (active low) MR(with a line on top) or SRCLR(with a line on top)
  11 clock pin SH_CP or SRCLK
  12 latch pin ST_CP or RCLK
  13 output enable (active low) OE(with a line on top)
  14 data pin DS or SER
  15 parallel output 1 QA or Q0
  16 5 volts supply VCC

  The connections between the 74HC595 and the sparkfun board are shown in the schematic and repeated below:

  74HC595 /  Sparkfun Breakout Board

  Q0 BLUE 4 and SWITCH 4
  Q1 BLUE 3 and SWITCH 3
  Q2 BLUE 2 and SWITCH 2
  Q3 BLUE 1 and SWITCH 1
  Q4 LED GND 4 (via current limiting resistor)
  Q5 LED GND 3 (via current limiting resistor)
  Q6 LED GND 2 (via current limiting resistor)
  Q7 LED GND 1 (via current limiting resistor)

  The remaining pins have the following connections to the Arduino (also shown in schematic):

  74HC595 / Arduino

  Vcc 5V
  GND GND
  DS Digital Pin 7
  OE(line on top) GND
  ST_CP Digital Pin 6
  SH_CP Digital Pin 5
  MR(line on top) 5V
  Q7' no connection

  The 74HC595s will be driving the LEDs in the sparkfun board. However, each chip only outputs 0 or 5V and it can output as much as 70mA. This means we must use current limiting resistors to prevent damaging the LEDs.

  From the specs of the LEDs I used:
  max forward current: 30mA
  forward voltage: 3.2V

  Calculate the resistance needed to achieve these max ratings from V = IR:

  resistance = (5V-3.2V) / (0.03A)
  = 60 ohms

  I used 68 ohm resistors so that I was not running at the absolute maximum, but also ensuring that I wouldn't lose too much brightness. (I made a mistake a grabbed the 100KOhm resistors when I made this project, I fixed it later, but the stripes of 100Ohm resistors should be blue, grey, black, gold, ignore the colors in the images).

  These are the sample calculations for the specific LEDs I used, you'll need to do you own calculations based on the specs of your LEDs. If you are unsure of what to do, use 220ohm or higher resistors; using too much resistance will make the LEDs less bright, but they will not be damaged.

  The pins connections to the 74HC595s should be as follows:

  Pin 15 - Blue 4
  Pin 1 - Blue 3
  Pin 2 - Blue 2
  Pin 3 - Blue 1
  Pin 4 - LED GND 4
  Pin 5 - LED GND 3
  Pin 6 - LED GND 2
  Pin 7 - LED GND 1

  data pin (pin 14) digital pin 7
  latch pin (pin 12) digital pin 6
  clock pin (pin 11) digital pin 5

  Each 74HC595 can only source 70mA at a time for all its pins. With the 100ohm current limiting resistors, if all 4 LEDs in a row are on at the same time (with multiplexing this is the max number of LEDs that can possibly be on at the same time), they will each draw about 18mA which puts the current requirements slightly above the 70mA maximum rating. I'll be drawing additional current from pins Q0-Q7 to multiplex the buttons (in later steps). An easy solution to this problem is to add another 74HC595 to the circuit, it will be wired parallel to the current 74HC595 (see schematic). This will give us additional 70mA to draw from on all 8 pins.

  Add another 16 pin socket to the protoboard and wire pins 1-7 and 15 of the sockets to each other (see note on schematic). These pins correspond to all eight outputs of the 74HC595s. 

  Connect pins 11, 12, and 14 of the sockets to each other. These correspond to the clock, latch, and data pins of the 74HC595s.

  Wire pin 10 to 5V (pin 16) and pin 13 to ground (pin 8). Pin 10 (MR) should be high and pin 13 (OE) should be low in order to send data to the output pins (Q0-Q7).

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