Figure 3. Solder to these connections.
It’s simple to use. Give it 3.5V-12V on VCC and GND,
and connect one channel of your audio to IN and the
second to GND. Adjust the pot to work with the level of the
input, and you’re in business; the LEDs will flash with the
music. What mikkojay figured out is
that he could tap into the LEDs. Each
time one of the LEDs lights up, you can
detect it with the Arduino. For this project, he only used
the middle three (Figure 3).
Figure 2. KA2284 VU meter.
Mikkojay’s original web page on the Jawduino:
KA2284 audio board; easier to get than they were a year
ago. Search Amazon and eBay for them.
UART control serial MP3 player — this is one listing:
Solder three wires to the bottom of the board on the
side of the LEDs that connect to the chip (not the side
closest to the edge; these go to a resistor and then to VCC.
Refer to the datasheet.) These three wires then go into
three of the analog inputs on the Arduino.
Here’s an example of how the angle of the servo is
increased as each successive LED is turned on:
Arduino Screw Shield:
Multiple vendors. I use one that comes in two parts, with
servo headers on it. This gives you the most possible
audio_value = 0;
if(analogRead(A0) < 341) audio_value += 60;
if(analogRead(A1) < 341) audio_value += 60;
if(analogRead(A2) < 341) audio_value += 60;
I also used a piece of acrylic to mount everything, with
standoffs. The unique component of this build is the
KA2284 board (Figure 2).
Get the assembled version if you can. Thankfully, the
available board follows the Samsung test circuit schematic.
The angle of movement is being increased more and
more as each successive LED is lit (e.g., the analog input
voltage goes under a specific threshold). If all three middle
LEDs are lit, then the maximum value hits 180. That is the
maximum swing (in degrees) used for the servo.
As the datasheet says, “The KA2284 is a monolithic
integrated circuit designed for five-dot LED level meter
drivers with a built-in rectifying amplifier.”
Once you’ve soldered the wires to the bottom of the
KA2284 board, then assembly is quick. I use the Screw
Shield because it makes things much easier; it has multiple
5V and GND connections:
Time for Assimilation
• KA2284 D2, D3, D4 to Arduino A0, A1, A2. VCC and
GND to Arduino 5V, GND.
• MP3 audio board RX to Arduino A3. VCC and GND to
Arduino 5V, GND.
• LED eyes to Arduino A4, GND, and pin.
• Jaw servo to Arduino A5. Use a servo cable.
46 SERVO 09.2017