Arduino SuperMini

Pinout

          PWR  D13     USB     RX   TX
          LED  LED             LED  LED
    D3 ~                                  RST
    D4                                     A5 SCL
    D5 ~                      Reset        A4 SDA
    D6 ~                       BTN         A3
    D7                                     A2
    D8                                     A1
    D9 ~                                   A0
SS  D10~   WS2821@D2                      VIN
    5V                                    GND
         ~D11  D12  GND  D13   RX   TX
         MOSI MISO       SCK

I still couldn't find the pinout of those solder pads on the back but they look suspiciously like a ISP interface.

RGB Blink Example

#include <Adafruit_NeoPixel.h>

#define PIN        13
#define NUMPIXELS   3

Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);

void setup() {
    strip.begin();
    strip.show();
}

void loop() {
    strip.setBrightness(10);

    setColor(255, 0, 0);     // Red
    delay(1000);

    setColor(0, 255, 0);     // Green
    delay(1000);

    setColor(0, 0, 255);     // Blue
    delay(1000);

    setColor(255, 255, 255); // White
    delay(1000);
}

// Set a color to all pixels at once
void setColor(int r, int g, int b) {
    for (int i = 0; i < strip.numPixels(); i++) {
        strip.setPixelColor(i, strip.Color(r, g, b));
    }
    strip.show();
}