The Flutter Explorer is a great general purpose add-on board for Flutter. It's got a bunch of different features that can be used for many different projects.

It can control 4 servos, 3 high current DC loads such as solenoids and pumps, has several connectors based on Seeed Studio's "Grove" sensor system for easy plug-and play use with a variety of sensors, displays, and more. It also features a loud piezo buzzer, DC barrel jack, USB full size B port, and 2-pin JST connector for lithium battery.

Full Feature List

4x Servo outputs

3x High current switches (MOSFET) with flyback diodes

1x Piezo Buzzer

1x 5.5 x 2.1mm DC Barrel Jack

1x Full size USB B port

2x 4-pin digital "Grove" connectors

1x 4-pin I2C "Grove" connector

1x 4-pin Serial "Grove" connector

1x 5-pin SPI Grove-style connector

3x 4-pin Analog "Grove" connector

1x 2-pin JST connector for Lithium polymer battery

Source files coming soon.