Shield for Adafruit Trinket that includes a battery charger and WS2812 LED.

Link to Github with BOM and details.

Photon Pixel Shield

The photon pixel shield is a small board for interfacing between a particle.io photon and some WS2812 based LED strips. Specifically, this board was made to drive Neopixel strips.

Power Requirements

The board takes in 5V only - up to 1A - and is used to power the photon and the pixel strip. Please note that current requirements are mostly driven by the number of LEDs being driven. Each WS2812 LED uses a maximum of 20mA, which can add up quickly. As such, at 1A, it is recommended to power at most 50 LEDs with this.

Digital Control

The WS2812 based LED strips can be controlled via the photon and the Neopixel library from Adafruit built by technobly. No digital pin is selected by default on the board. Pin D2 is the default in the library. To use the default connect the solder jumper for D2 on the back of the board. Otherwise, you may select almost any digital pin in both software on through the jumper on the board.

BOM

The majority of the BOM, which as of 3/18/2016 can be found on mouser, is around $4. A simple 3mm power LED is required if you wish to have a power indicator. The resistor marked 330ohm on the board is for the LED. Replace with an appropriate resistor value for an LED chosen.

GPIO Expander - Arduino Shield

16 Channel general purpose IO expander for Arduino Uno R3 boards. Provides higher current (500mA) and voltages (50V) per pin than Arduino. Voltage via Vin from Arduino or separate DCC jack - up to 50V and 500mA per pin. This uses the i2c interface, which is shared, so does not utilize any of the dedicated I/O pins of the Arduino. Each board is addressable via jumpers for up to 8 expanders on one Arduino plus possibly additional i2C devices depending on the addresses.

BOM:

1x MCP23017 - Microchip MCP23017-E/SP - Mouser Part

2x ULN2803A - STMicroelectronics - Mouser Part

1x CUI Inc PJ-202A - Sparkfun PRT-00119 (Optional - Only needed if you plan to NOT use Vin from Arduino Uno)

Optional Shield Stacking Headers - Useful to stack shield with other shield - not that all pins are transferred up to next shield.

1x - Shield Stacking Headers Kit - Adafruit

Optional male pins for jumpers for board - since the spacing is standard .1 inch (2.54mm) there are many options.

2x 2x5 90deg Header - suggested 90 deg headers for outputs if stacking shields - Mouser Part

4x Jumpers - Mouser Part

1x 1x12 Header - Break into 4x 1x3 for A0, A1, A2, Power Selectors Mouser Part

Arduino Library

Use the Adafruit MCP23017 library for this i2c connector.

Source Files

Eagle .brd and .sch files on github