We sure love the ATmega328 here at Adafruit, and we use them a lot for our own projects. The processor has plenty of GPIO, Analog inputs, hardware UART SPI and I2C, timers and PWM galore - just enough for most simple projects. When we need to go small, we use a Pro Trinket 3V or 5V, but when size isn't as much of a concern, and a USB-serial converter is required, we reach for an Adafruit METRO.

METRO is the culmination of years of playing with AVRs: we wanted to make a development board that is easy to use and is hacker friendly.

ATmega328 brains - This popular chip has 32KB of flash (1/2 K is reserved for the bootloader), 2KB of RAM, clocked at 16MHz

Power the METRO with 7-9V polarity protected DC or the micro USB connector to any 5V USB source. The 2.1mm DC jack has an on/off switch next to it so you can turn off your setup easily. The METRO will automagically switch between USB and DC.

METRO has 20 GPIO pins, 6 of which are Analog in as well, and 2 of which are reserved for the USB-serial converter. There's also 6 PWMs available on 3 timers (1 x 16-bit, 2 x 8-bit). There's a hardware SPI port, hardware I2C port and hardware UART to USB.

GPIO Logic level is 5V but by cutting and soldering closed a jumper, you can easily convert it to 3.3V logic

USB to Serial converter, there's a hardware USB to Serial converter that can be used by any computer to listen/send data to the METRO, and can also be used to launch and update code via the bootloader

Four indicator LEDs, on the front edge of the PCB, for easy debugging. One green power LED, two RX/TX LEDs for the UART, and a red LED connected to pin PB5

Easy reprogramming, comes pre-loaded with the Optiboot bootloader, which is supported by avrdude and only uses 512 bytes.

Beautiful styling by PaintYourDragon and Bruce Yan, in Adafruit Black with gold plated pads.

Works with all Adafruit designed shields!

This version of the METRO 328 comes as a fully assembled and tested development board but without any headers attached. We do include some through-hole headers that you can solder on if you like, or you can solder wires or header directly to the breakout pads. We also include 4 rubber bumpers to keep it from slipping off your desk.

Mac & Windows People! Don't forget to grab & install the FTDI VCP drivers from FTDI to make the COM/Serial port show up right! The default drivers may not support this FTDI chip!

Using our muscles to control things is the way that most of us are accustomed to doing it. We push buttons, pull levers, move joysticks… but what if we could take the buttons, levers and joysticks out of the equation? This is the MyoWare Muscle Sensor, an Arduino-powered, all-in-one electromyography (EMG) sensor from Advancer Technologies. The MyoWare board acts by measuring the filtered and rectified electrical activity of a muscle; outputting 0-Vs Volts depending the amount of activity in the selected muscle, where Vs signifies the voltage of the power source. It’s that easy: stick on a few electrodes (not included), read the voltage out and flex some muscles!

The MyoWare Muscle Sensor is the latest revision of the Muscle Sensor of old, now with a new wearable design that allows you to attach biomedical sensor pads directly to the board itself getting rid of those pesky cables. This new board also includes a slew of other new features including, single-supply voltage of +3.1V to +5V, RAW EMG output, polarity protected power pins, indicator LEDs, and (finally) an On/Off switch. Additionally, we have developed a few shields (Cable, Power, and Proto) that can attach to the Myoware Muscle Sensor to help increase its versatility and functionality!

Measuring muscle activity by detecting its electric potential, referred to as electromyography (EMG), has traditionally been used for medical research. However, with the advent of ever shrinking yet more powerful microcontrollers and integrated circuits, EMG circuits and sensors have found their way into all kinds of control systems.

Note: Biomedical sensor pads can be found in the Recommended Products section below to be purchased separately.

Get Started with the MyoWare Muscle Sensor Guide

Features

Wearable Design

Single Supply

+2.9V to +5.7V

Polarity reversal protection

+2.9V to +5.7V

Polarity reversal protection

Two Output Modes

EMG Envelope

Raw EMG

EMG Envelope

Raw EMG

Expandable via Shields

LED Indicators

Specially Designed For Microcontrollers

Adjustable Gain

0.82" x 2.06"

Pimoroni love the little SN3218A chip they used to make PiGlow so much that they've decided to turn it into a handy little breakout module. This is a super low-cost way to drive 18 LEDs at constant current up to 34mA per channel. Simply hook up the cathode of your LEDs to the channel and provide a common 5V supply for the anodes and away you go!

2.75 - 5.5V supply and logic voltage

Up to 34mA per channel constant current sinking (adjustable)

Bread-board compatible format

I2C interface (address 0x54)

Supplied with 0.1" headers to solder yourself

The I2C interface is very simple to use and works with Raspberry Pi, Arduino, and most other platforms - the device address is 0x54. With the Raspberry Pi you can use the 3V3 supply to power the chip (via the VCC pin on the breakout board) and the 5V supply to power the LEDs. There is also an Arduino library available

If music be the food of love, play on. But make sure you use this super little pHAT DAC to get the best out of your Raspberry Pi audio!

The pHAT DAC provides a super affordable high-quality DAC for the Raspberry Pi. Pumping out 24-bits at 192KHz of audio goodness from the Raspberry Pi's I2S interface on the 2x20 pin GPIO header. Since it's digital audio, it sounds really good, much better than the onboard analog audio. The 3.5mm stereo jack comes soldered onto the board already.

Though designed to match the format of the Raspberry Pi Zero it is compatible with all 40-pin GPIO Raspberry Pi variants (2/B+/A+).

Features:

24-bit audio at 192KHz

Line out stereo jack

pHAT format board

Uses the PCM5102A DAC to work with the Raspberry Pi I2S interface

Kit includes: Assembled pHAT DAC & 2x20 0.1" female GPIO header, some light soldering is required to attach the header on, or you can of course solder the pHAT right onto the Pi Zero

At the heart of pHAT DAC is Texas Instrument's PCM5102A stereo audio DAC chip. Raspberry Pi not included!

Pulse Sensor Amped is a greatly improved version of the original Pulse Sensor, a plug-and-play heart-rate sensor for Arduino and Arduino compatibles. It can be used by students, artists, athletes, makers, and game & mobile developers who want to easily incorporate live heart-rate data into their projects.Pulse Sensor Amped adds amplification and noise cancellation circuitry to the hardware. It's noticeably faster and easier to get reliable pulse readings. Pulse Sensor Amped works with either a 3V or 5V Arduino.Lastly, the Pulse Sensor creators have also streamlined and improved the Processing visualization software and Arduino code that comes with this hardware.The kit includes:

A 24-inch Color-Coded Cable, with a standard male header connectors. Plug it straight into an Arduino or a Breadboard. No soldering is required.

An Ear Clip, perfectly sized to the sensor. It can be hot-glued or epoxied to the back of the sensor to get reading from an ear lobe.

Parts to make a handy Velcro finger strap. This is another great way to get heart-rate data.

4 Transparent Stickers, to insulate the front of the Pulse Sensor from oily fingers and sweaty earlobes.

The Pulse Sensor has 3 holes around the outside edge which make it easy to sew it into almost anything.

Visualization software (made in Processing) to instantly see output of the sensor and for troubleshooting.

The WAV Trigger is a unique high-fidelity polyphonic audio player with surprising capabilities. Supporting up to 2048 uncompressed 16-bit, 44.1kHz wav files – the same quality as an audio CD – the WAV Trigger can play and mix up to 14 stereo tracks simultaneously and independently, with very low latency. Tracks can be controlled via 16 programmable trigger inputs, or by using a native serial control protocol or even MIDI.

Trigger inputs can be connected directly to switches and buttons, or to digital outputs from sensors or another microcontroller. Alternate functions can be specified using a free cross-platform GUI application, and allow triggers to play sequential or random tracks, pause and resume groups of tracks and even control volume. An Arduino library allows for complex serial control like real-time mixing, starting multiple tracks in sample-sync and smooth cross-fading between tracks.

On-board sample rate conversion allows for smoothly changing playback speed/pitch from 0.5x to 2x. in real-time.

MIDI allows you to use the WAV Trigger as a polyphonic sampling synthesizer to play your own sounds from any MIDI keyboard controller. MIDI Channels and Note numbers are mapped to track numbers, and MIDI Controllers adjust volume as well as attack and release times. MIDI Program Change is supported to switch between up to 16 banks of 128 sounds. The WAV Trigger audio engine even implements, pitch bending, voice stealing (oldest playing voices are used for new MIDI Notes when all 14 voices are being used), note attack (fade-in), note release (fade-out) and latency averages 8 ms.

The WAV Trigger supports both SDSC (up to 2GB) and SDHC (up to 32GB) type microSD cards.

Check the link in the documents below to keep up with the latest Firmware updates!

Note: This product is a collaboration with Robertsonics. A portion of each sales goes back to them for product support and continued development.

Features

Supports up to 2048 uncompressed 16-bit stereo WAV files at 44.1kHz – CD quality

Polyphonic! Play and mix up to 14 stereo tracks independently and simultaneously

Sample-accurate starting and playback of up to 14 parallel stereo tracks

Trigger-to-sound delay: 8 msecs typ, 12 msecs max

MIDI control: Velocity-sensitive triggering of up to16 banks of 128 tracks

Real-time playback rate control and MIDI Pitch Bend

Pause and resume individual or groups of tracks. Multiple random trigger ranges

True line-level stereo output: 2.1V RMS ground centered, 100dB SNR

On-board mono audio amplifier and speaker connector: 2W into 4 Ohms, 1.25W into 8 Ohms

16 trigger inputs are individually adjustable for contact closure, 3.3V or 5.0V control

Trigger inputs can be individually inverted, and/or set to be edge, latched or level sensitive

Volumes adjustable from +10dB to -70dB in 0.5dB increments

Firmware volume fades (attacks & decays) and cross-fades

A dedicated “Play” status digital output pin

3.3V and 5.0V output pins

Extensive serial control. Arduino library available. Pin compatible with SparkFun FTDI Basic