The littleBits mp3 Player allows you to play your very own mp3 files using littleBits. Sending a signal to the mp3 player can make it work as a media player, sampler, or looper. Just load the mp3 files you want onto the provided SD card and you'll have music and sound effects in your next littleBits project in no time. The mp3 player reads mp3 files off of the SD card that is underneath the bit. To choose the order that files are played in simply rename the mp3 file so that it has a number in front of the file name. The mp3 player will then play your mp3 tracks in numerical order. Use the 'back' and 'forward' buttons to switch between tracks on the mp3 player. If you are in the middle of a song then double click the 'back' button to go to the previous track. Playback is started by sending a pulse or latch through the input signal line to the bit. The behaviour of playback thereafter depends on which of the four modes is selected. ONCE MODE: Once mode behaves much like a retrigger sampler. It will play only the current selected track. Begin playback by giving an input signal pulse to the bit. After a track is finished playback will stop. Subsequent triggers will repeat the same track. If a pulse is sent during playback it will start playback of the track from the beginning. LOOP MODE: Loop mode continuously plays the same track repeatedly. An input pulse or latch will start playback of the looped track. A subsequent pulse or latch stops playback of the track. NEXT MODE: Next mode plays a track and then upon subsequent input pulses will automatically start playback of the next track in the queue. Once a track finishes playing playback will stop. ALL MODE: All mode behaves most like a traditional mp3 player. Playback is started and it will play all songs loaded on the SD card in order, without interruption. Input pulses or latches will stop and resume playback. VOLUME CHANGE: If you find the maximum volume of the mp3 player is not suitably loud enough, you can add 12dB of gain by simultaneously pressing the back and forward buttons at the same time. To remove the extra boost, press the two buttons again to switch back to normal mode. HEADPHONE/BITSNAP OUT: You can either send the audio signal out through the headphones or through the output bitsnap. When headphones are connected to the bit audio will not be carried through the output bitsnap.  UNDER THE HOOD An Atmega168 is used to read data from the SD card. It also handles all playback options that are selectable on the card. MP3 decoding is done through the VLSI1053 IC. The VLSI handles the playback of all audio and makes requests to the Atmega168 when it needs more data to process. The VLSI then outputs the left and right channel data to the headphone jack. When headphones are not connected the two signals are mixed and amplified so that both channels are merged onto a single line so the audio can be passed to the bitsnap out.

The sequencer allows you to connect up to eight outputs and control them in sequential patterns. Sequences that would take as long as 4 days to program without littleBits will only take you seconds! Automatically cycle through the entire sequence Control the speed of the sequence using dimmers or sensors Run the sequence four ways: forwards, backwards, pendulum, or random Swap automation for full control and step through each part of the sequence using a button, sound trigger, or any other high signal input There are two clock modes that control when the module transitions from sequence step to sequence step. In “step” mode the sequence transitions to a new sequence step on input low-to-high transitions. In this mode, the clock output is high when the input is above 2.5V, and the clock output is low when the input is below 2.5V. In “speed” mode the sequence transitions to a new sequence step at a fixed frequency. The step frequency is proportional to the voltage at the input. At 0V input, the frequency is 0Hz (the sequencer does not step). At 5 volts the step frequency is approximately 80Hz. In this mode, the clock output is a square waveform at the step frequency The four sequence modes control the order in which the 8 sequenced outputs are activated. At any given time, there is exactly one of the 8 sequenced outputs set to 5V. All other outputs are set to 0V. “Forward” mode sets output 1 to 5V, then on the next step output 2 is set to 5V, and so on. After activating each output in turn, the sequence then continuously repeats, starting at output 1. “Backwards” mode is the same as “forward” mode, except that the sequence steps from output 8 to output 1 and is set to 5V at each step. “Pendulum” mode sets output 1 to 5V, then on the next step output 2 is set to 5V, and so on. Upon reaching output 8, the sequence reverses and steps down from 7 to 1. “Random” mode sets a randomly selected output to 5V at each step. UNDER THE HOOD The input signal is buffered by an opamp (U1), then passed through a single pole RC low pass filter, then a 2-pole active low pass filter (U3). The combined filters band limit the signal to 160Hz with an 18dB per octave filter slope. This signal is split into two paths. One path leads to the Analog-to-Digital Converter (ADC) of an Atmel ATMEGA168 microcontroller (U2). The other path leads to a General Purpose Input-Output (GPIO) pin on the same microcontroller. The path to the ADC is used in “speed” mode because in speed mode, we need to precisely measure the input voltage, and the ADC is precise. The path to the GPIO pin is used in “step” mode, because we need to quickly measure the timing of an input low-to-high transition, and the GPIO pin responds very quickly to transitions. Depending on the clock mode, microcontroller converts the measured input values into either the sequencer step speed in “speed” mode, or simply goes to the next sequencer step when it detects a low-to-high transition in “step” mode. These values are translated into signals that control the pins of the microcontroller connected to the various outputs.

The motion trigger is similar to the sensor on an automatic door: when someone is moving nearby, it sends an ON signal to the following Bits. It's very sensitive, so don't breathe unless you want to be detected! Try it with some LEDs to create a security light!

The littleBits micro sequencer sends out voltages based on the position of each of the four “step” knobs. Connect it to an oscillator and it will step through the "sequence" consecutively to make a melody (The LEDs tell you which step is active). Turn a knob all the way counter-clockwise to make the step silent. Use it in "speed" mode to set the speed using the dial, or flip the switch to “step” mode to use an input module like a pulse or button for control. In addition to its main output, it also has a trigger output, which you can send to any of your other Bits modules.

The keyboard lets you play melodies- it features 13 switches that make up an entire octave of notes. It has two modes: "press" (which only produces output when you press a switch) and "hold" (which will hold the last note you played). It also features an octave control which changes the playable range. In addition to its main output, which is great for controlling our oscillators, it also has a "trigger out", which you can send to the "trigger in" of envelope or other littleBits modules.

The littleBits temperature sensor responds to the temperature surrounding its probe. The higher the temperature it senses, the more signal it sends out. The temperature sensor determines temperature via the IC that is located on top of the board. It communicates via I2C with an MCU located on the bottom of the board. The MCU gets a temperature reading in Celcius, applies a hysteresis to the reading, then converts it to farenheit if necessary. The final determined temperature is converted to a number module readable analog value. Every 50mV on the output of the bitsnap represents a single degree in either Farenheit or Celcius. Since heat will conduct through the board itself, there are slots around around the temperature sensor which provide thermal relief from board conductivity. Not Waterproof: littleBits are not waterproof. Please do not put the temperature sensor in your mouth to take your temperature. Plus, they taste weird so you will wish you hadn’t.

The pressure sensor is a touch-activated module; give its pad a little squeeze to activate it. The more pressure you apply, the more signal it sends out. Put it in front of a vibration motor to control how much it shakes!

The littleBits mix module allows you to combine two inputs and send them to a single output. It also has a volume control for each of its inputs - that's where the 'mixing' comes in. Use it to play two oscillators on a single speaker!

The littleBits envelope modifies the loudness contour of a sound. It takes a sound input and shapes it into something you'd hear from an acoustic musical instrument, like a piano or saxophone. This envelope has two controls: "attack", which is how long it takes to ramp up to maximum volume, and "decay", which is how long it takes to go down to silence again. You can use its third bitSnap[TM] to trigger the envelope from different sources, like the keyboard. [Try it putting the envelope after an oscillator being controlled by a micro sequencer.]

The microphone Bits module translates sound into the electronic language of littleBits. You can use it to turn sounds into light or motion, or use it with the speaker Bits module like a small megaphone! Make sure the switch is set to “sound” when you're using it with the speaker, and “other” for all your other modules, like LEDs and motors. The microphone Bits module also has a 3.5 mm input jack so you can plug in your computer or mp3 player.

The littleBits filter has the most effect on the sound’s character or “timbre”. It affects the timbre by changing the relative volume of certain frequencies in the sound. Use it to give the impression that a sound is “brighter" (more high frequencies) or “darker” (more low frequencies.) The "cutoff" knob sets the frequency to be emphasized, and the other controls 'peak,' or intensity of the filter. If the peak is turned up all the way, the filter turns into an oscillator! [This is great for shaping all of the sounds you can make with the Synth Kit, but it's especially good with a noise input.]

The oscillator is the main sound source in the Synth Kit and is capable of creating audio tones that will be used in almost every sound experiment you create. It features a "pitch" knob to adjust its output tone and a "tune" dial for adjusting the tuning when using with the keyboard. It also features a mode switch that selects between "square" and "saw" waveforms. The "square" waveform has a rich, powerful character, and the "saw" waveform has a more mellow, rounder character. [You'll often use it after the Keyboard or Micro Sequencer Bits modules, but you can have lots of fun by just twisting the pitch knob and "sweeping" through all the frequencies from high to low pitches.]

The littleBits delay module takes incoming audio and repeats it, like an echo. It has two knobs: "time", which sets the delay length between a sound and its repetition, and "feedback", which controls how many times the sound repeats. Delays can be long and spacey, like shouting into the Grand Canyon, or loud and crazy. This Bits module will play forever if you turn up the Feedback knob all the way. [You can also shift the pitch of a sound by turning the "time" control while a sound is repeating.]

The littleBits random module has two modes: "noise" and "random voltage". In "noise" mode, it outputs white noise, like a television set not tuned to any channel. In "random voltage" mode, it outputs random voltage signals that can control oscillators and make them play random pitches. Use the "trigger out" connector and "speed" dial of the micro sequencer to set the timing of the random output pulses and use an input Bits module like a dimmer to control the range of your random outputs.

The littleBits light sensor measures how much light is shining on it. It has two modes: “light” and “dark”. In “light” mode, the more light shines on the sensor, the higher the signal it sends out. In “dark” mode, it's just the opposite – the signal increases the darker it gets. You can use a screwdriver to adjust the sensitivity. Use a bargraph to see how it's working!

The sound trigger listens to the noise level in your room, and sends an ON signal when it gets over a certain level. You can make that threshold louder or softer using the included screwdriver. We like to use it with an LED to light up your room when you snap your fingers. The sound trigger features an electret microphone that triggers a 5V output when the set threshold is reached. The output of the module will remain high for 3 seconds. If the input signal is high, the module functionality is enabled. If the input signal is low, the module function is disabled.

The remote trigger lets you use a common remote control with your modules. Make your littleBits circuit and point your remote control at the remote trigger’s sensor. Then, press any button on your remote control to activate the module. The remote trigger will work with almost any button on a remote that uses infrared light to send signals.

The pulse Bit is like an electronic heartbeat. It sends out a stream of short ON signals, and you can make the speed of the pulses faster or slower using the included screwdriver. It's great for making LEDs blink!

The timeout Bit is a settable timer. Try it after a button and follow it with a light. Press and release the button to start the countdown. In "on-off" mode, the light will go on as soon as you release the button and the timer will start counting down to turn-off time. In "off-on" mode, the light will go out when you release the button and will turn back on after the timer reaches the allotted time. Use the included screwdriver to set the timer. Try it with a motion sensor and buzzer to create an intruder alarm!

The proximity sensor Bit senses objects in front of it. It can sense if an object is far or near. Try using it to create your own self-navigating car, or a hands-free instrument!

The toggle switch Bit is sturdy on/off switch that you can use to activate your creations with a nice, solid click. Try using it after a USB power Bit as an on/off switch for your whole creation.

Think of the littleBits threshold as a toll booth for signal passing through your circuit. The threshold compares the incoming voltage coming from the bit snapped before it against the voltage amount you’ve set by the threshold knob. If the incoming voltage value is greater than the selected voltage, the threshold will allow the signal to pass and activate any bits (lights, motors, etc…) following it. If not, then nothing will be activated. Use it to make any sensor module into a trigger module! The threshold is a minimum parts count design, using only a single opamp to accomplish the task of comparing the input signal to an onboard reference that is set via the potentiometer control. U1 is configured as a non-inverting comparator with approximately 100mV of hysteresis provided by R1 and R3. VR1 provides the comparator's reference. C1 is a bypass capacitor for U1 that sources current to the opamp during fast switching events.

The littleBits slide switch is a small and convenient way to turn your creations on and off. It uses a sturdy plastic lever to switch back and forth. Try it with any of your favourite Bits, like the DC motor or bright LED!

It functions just like a light dimmer you might find at home, or a volume fader in a recording studio. Follow it with an LED for some adjustable mood lighting.