connector. This sends 5V from the FTDI connector to the power input of the board, bypassing the
charge circuitry that limits the current. Once you do this, you'll be able to power the board from the
FTDI connector. Did we mention not to connect a Lipo battery to the board after you make this
modification?
Solder jumpers
There are several solder jumpers on the board that you can use to alter its behavior. You probably
won't need them, but they're there if you're ambitious.
I2C pullups (SJ1 and SJ2)
The TPA2016D2 amplifier chip has an I2C ("wire" library) interface that can be used to alter various
settings on the chip. This interface is connected to the ATmega328 and is also sent to trigger 2 and
trigger 3 in case you want to use external I2C sensors such as accelerometers, gyroscopes, etc.
In the example sketches, the I2C interface is normally disabled and generally shouldn't interfere
with the use of trigger 2 or trigger 3. However, if you'd like to absolutely separate trigger 2 and
trigger 3 from the amplifier chip and 4.7K pullup resistors, you can do so by cutting SJ1 and SJ2.
These jumpers are normally connected (there's a thin trace running between the pads). If you want
to sever the I2C connection to the amplifier, carefully cut the traces between the pads using a
hobby knife. If you'd like to restore the connection later, use a blob of solder to reconnect the two
pads.
Serial MIDI connection (SJ3)
SJ3 (on the bottom of the board) can be used to connect the serial RX line (trigger 5) to the serial
RX pin of the VS1053B audio decoder chip. This will let you send serial MIDI data directly from
trigger 5 to the audio decoder.
Please note
that without changing this jumper, you can still play MIDI files from the SD card just
like any other audio file. This jumper is only useful if you have an external MIDI source such as a
keyboard that you might want to connect directly to the LilyPad MP3 Player.
Headphone jack speaker cutoff (SJ4 and SJ5)
Normally, when you plug headphones into the jack, the audio signal to the amplifier chip and
speakers will be interrupted by switches built into the jack. If you would rather have audio go to both
the headphone jack and amplifier, you can close solder jacks SJ4 and SJ5 on the bottom of the
board.
Even more headers
If you need more I/O than the five trigger pins, and you're not going to be using a rotary encoder,
you can take advantage of the unused rotary encoder connections in the center of the board. The
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