const int dataPin = 0;   /* DS */
const int clockPin = 1;  /* SHCP */
const int latchPin = 2;  /* STCP */

void setup() {
  randomSeed(analogRead(A0));
  pinMode(dataPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(latchPin, OUTPUT);
}

void loop() {
  // show(); // various
  r();
}

void show() {
  // int leds[] = {0xC6, 0x3A}; // 8
   int leds[] = {0x80, 0x40, 0x02, 0x08, 0x10, 0x20, 0x02, 0x04}; // snake
  // int leds[] = {0x80, 0x40, 0x20, 0x10, 0x08, 0x04}; // circle
  // int leds[] = {0x80, 0x10}; // top bottom
  // int leds[] = {0x80, 0x02, 0x10, 0x02}; // wigwag top middle bottom
  // int leds[] = {0x60, 0x0C}; // left right
  // int leds[] = {0x40, 0x04, 0x20, 0x08}; // wave
  // int leds[] = {0x48, 0x24}; // left right
  // int leds[] = {0x4a, 0x26}; // H
  // int leds[] = {0x46, 0x2A}; // toetouch
  int num = sizeof(leds) / sizeof(leds[0]);
  for (int i = 0; i < num; i++) {
    byte pattern = leds[i];
    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, LSBFIRST, pattern);
    digitalWrite(latchPin, HIGH);
    delay(100);
  }
}

void r() {
  byte pattern = 0b1 << random(7);
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, pattern);
  digitalWrite(latchPin, HIGH);
  delay(250);
}

/************************************************************************************************
  ATTINY85                             +-- --+
             PCINT5/-RESET/ADC0/dW/PB5 |1 * 8| VCC
      PCINT3/XTAL1/CLKI/-OC1B/ADC3/PB3 |2   7| PB2/SCK/USCK/SCL/ADC1/T0/INT0/PCINT2
  PWM4/PCINT4/XTAL2/CLKO/OC1B/ADC2/PB4 |3   6| PB1/MISO/DO/AIN1/OC0B/OC1A/PCINT1/PWM1
                                   GND |4   5| PB0/MOSI/DI/SDA/AIN0/OC0A/-OC1A/AREF/PCINT0/PWM0
                                       +-----+

  SEGMENTS
     A
    ---
  F| G |B
    ---
  E|   |C
    --- o DP
     D

   PINS D13 D12 D11 D10 D09 D08 | D07 D06 D05 D04 D03 D02 Tx  Rx  | A05 A04 A03 A02 A01 A00 RST
   PORT PB5 PB4 PB3 PB2 PB1 PB0 | PD7 PD6 PD5 PD4 PD3 PD2 PD1 PD0 | PC5 PC4 PC3 PC2 PC1 PC0 PC6
   SEGS  -   -   -  dp   g   f  |  e   d   c   b   a   -   -   -     -   -   -   -   -   -   -
************************************************************************************************/