/*
 * Demo program for ATtiny45 Hello Board
 * Program reads pushbutton switch, sends
 * appropriate message through FTDI and
 * controls LEDs (ON/OFF/SLOW Blink/Fast Blink
 * 
 * Uses software serial for TXD, RXD
 * Connections:
 *  LED - PB4 (4)
 *  PB  - PB3 (3), Internal Pull-up resistor
 *  TXD - PB2 (2), t45 rx
 *  RXD - RB1 (1), t45 tx
 *  
 *  States:
 *   0  - LED off
 *   1  - LED on
 *   2  - SLOW Blink
 *   3  - FAST Blink
 *   
 *   Steven Chew  2020-03-10
 *   
 *   This work may be reproduced, modified, distributed,
 *   performed, and displayed for any purpose, but must
 *   acknowledge this project. Copyright is retained and
 *   must be preserved. The work is provided as is; no
 *   warranty is provided, and users accept all liability.
 */

#include <SoftwareSerial.h>
#define LED_pin 4
#define PB_pin 3
#define TX 1
#define RX 2
#define END_STATE 4
#define SLOW_DLY 500
#define FAST_DLY 150

SoftwareSerial mySerial(RX, TX);  // ATtiny45 rx, tx
uint8_t state = 0;  // initial state LED off
uint8_t ledStatus = 0;  // tracks led status, 0 - off, 1 - on
uint16_t dlyInterval;   // blink interval

void setup() {
  // put your setup code here, to run once:
  pinMode(LED_pin, OUTPUT);
  pinMode(PB_pin, INPUT_PULLUP);
  digitalWrite(LED_pin, LOW);   // led off at start
  mySerial.begin(9600);   // transmit at 9600 bps
  mySerial.println("Start state: LED off");
}

void loop() {
  // put your main code here, to run repeatedly:
  // check for pushbutton press
  if (digitalRead(PB_pin) == LOW){  // pb pressed
    delay(10);  // switch debounce
    while (digitalRead(PB_pin) == LOW); // wait for pb release
    
    state++;  // transition to next state
    if (state == END_STATE) // check of last state
      state = 0;  // reset to start state

    switch (state){
      case 0: mySerial.println("State 0: LED off");
              break;
      case 1: mySerial.println("State 1: LED on");
              break;
      case 2: mySerial.println("State 2: SLOW blink");
              break;
      case 3: mySerial.println("State 3: FASET blink");
              break;
      default: mySerial.println("Error! Unknown stte");
    }
  } // end if
  
  switch (state){
    case 0: // LED off
      // mySerial.println("State 0: LED off");
      ledStatus = 0;
      digitalWrite(LED_pin, LOW);
      break;
    case 1: // LED on
      // mySerial.println("State 1: LED on");
      ledStatus = 1;
      digitalWrite(LED_pin, HIGH);
      break;
    case 2: // slow blink
    case 3: // fast blink
      if (state == 2){
        // mySerial.println("State 2: Slow blink");
        dlyInterval = SLOW_DLY;          
      } else {
        // mySerial.println("State 3: Fast blink");
        dlyInterval = FAST_DLY;
      }
      if (ledStatus == 0){
        digitalWrite(LED_pin, LOW); // turn off LED
        ledStatus = 1;          
      } else {
        digitalWrite(LED_pin, HIGH);  // turn on LED
        ledStatus = 0;
      }
      delay(dlyInterval);
      break;
   }  // end switch-case
}