//******************************************************************************
//  Coder on MSP430 for RC toy remote control (RX2/TX2 set). IR version
//     *replacing TX2 chip (in IR transmitter) with MSP430F20xx
//
//            +3V   -----------------                        _|_  +3V
//             |   |              XIN|- X --                 \ /
//             ----|RST              |    32kHz (for cal.)   --- LED (IR)
//                 |             XOUT|- X --          ___     | 
//     ------------|P1.0             |          -----|___|-----
//  SW1|  ---------|P1.1             |          |D    R1  10 to 470 Ohms
//    \   |  ------|P1.2         P1.4|_ _ _ _G|/ 
//     | \   |  ---|P1.3             |        |\.  T1 2N7000 (2N7002)  
//    --- | \   |  |                 |          |S
//       --- | \       MSP430F20xx             ---
//          --- |SW4
//             ---                                      SK_Lab 2019
//  Thanks to Texas Instruments, Inc
//  Built with CCS Version: 7.4.0.x. Flash/FRAM = 946 bytes. RAM = 51 bytes.
//******************************************************************************

#include <msp430.h>
char command=0;
void try_to_choose (char a);
void try_to_send (char b);
int main(void)
{
   WDTCTL = WDTPW + WDTHOLD;                // Stop watchdog timer
  DCOCTL = 0x6C;                          // ~ 303kHz
  BCSCTL1 = 0x83;                         // ~ 303kHz
  BCSCTL2 |= DIVS_3;                      //SMCLK = MCLK/8 = 38 kHz
   P1OUT &= ~BIT4;                          // Set P1.4 output to 'Lo' (IR 'OFF')
   P1DIR |= BIT4;                           // Set P1.4 to output direction
  P1REN |= 0x0F;                          // P1.0,1,2,3 pullup resistors
  P1IE |= 0x0F;                           // P1.0,1,2,3 interrupt enabled
  P1IES |= 0x0F;                          // P1.0,1,2,3 interrupt on Hi/lo edge
  P1IFG &= ~0x0F;                         // P1.0,1,2,3 IFG cleared

  __bis_SR_register(LPM3_bits + GIE);       // Enter LPM3 w/interrupt
}

        //Next will happen if level at any of P1.0,1,2,3 has fallen level (button pressed)
#pragma vector=PORT1_VECTOR
__interrupt void Port_1(void)
{
        //Will stuck in this loop if you hold buttons pressed.
    while ((P1IN & 0x0F) != 0x0F)             //Is any button stay pressed?
    {
        command = ((P1IN & 0x0F) ^ 0x0F);     //Read buttons & convert to 0...15
        try_to_choose (command);              //Conversion & send
    }
    P1IFG &= ~0xF0;                           // P1.4 IFG cleared
}

        //Choose the command (num. of pulses to transmit) vs button pressed;
void try_to_choose (char a)
{
    switch( a )
     {
       case  0x01: try_to_send (58); break;                  //0001 - 58
       case  0x02: try_to_send (40); break;                  //0010 - 40
       case  0x03: try_to_send (52); break;                  //0011 - 52
       case  0x04: try_to_send (10); break;                  //0100 - 10
       case  0x05: try_to_send (28); break;                  //0101 - 28
       case  0x08: try_to_send (64); break;                  //1000 - 64
       case  0x0A: try_to_send (46); break;                  //1010 - 46
       case  0x0C: try_to_send (34); break;                  //1100 - 34
     }
}
        //Generates 4 pulses as "start" and amount of DATA pulses, as in variable 'b'.
void try_to_send (char b)
{
char counter_st_pls = 4;                    //Will be 4 "Start" pulses
while (counter_st_pls)                      //loop, 4 times
    {
    __delay_cycles(455);  P1SEL |= 0x10;    //After "Space" time (1.5mS/3.3uS=455) 38kHz ON
    __delay_cycles(152);  P1SEL &= ~0x10;   //Await "Pulse" time (0.5mS/3.3uS=152) 38kHz OFF
    counter_st_pls--;
    }
        while (b)                           //Will be 'b' "DATA" pulses w/"Spaces"
        {
        __delay_cycles(152);  P1SEL |= 0x10;     //The same, "Space", 0.5mS
        __delay_cycles(152);  P1SEL &= ~0x10;    //The same, "Pulse", 0.5mS
        b--;
        }
    P1SEL &= ~0x10;     //Turns off 38kHz (SMCLK=MCLK/8) on P1.4 and leaves pin in Lo     
}
/* P.S. For a 38kHz carrier, we use SMCLK that can be sent to P1.4 directly.
/******************************************************************************/