//******************************************************************************
//  Coder on MSP430 for RC toy remote control (RX2/TX2 set)
// *replacing TX2 chip (in RF transmitter) with MSP430F20xx
//
//            +3V   -----------------
//             |   |              XIN|- X --
//             ----|RST              |     32kHz (for IR calibration)
//                 |             XOUT|- X --
//     ------------|P1.4             |
//  SW1|  ---------|P1.5             |
//    \   |  ------|P1.6         P1.3|--> to RF modulator (0V to +3V)
//     | \   |  ---|P1.7             |     (or LED (1k to +3V req.))
//    --- | \   |  |                 |
//       --- | \       MSP430F20xx
//          --- |SW4
//             ---                                      SK_Lab 2019
//  Thanks to Texas Instruments, Inc
//  Built with CCS Version: 7.4.0.x. Flash/FRAM = 962 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
  BCSCTL1 = CALBC1_1MHZ;                    // For 1MHz. Set range
  DCOCTL = CALDCO_1MHZ;                     // For 1MHz. Set DCO step + modulation */
  P1DIR |= 0x08;                            // Set P1.3 to output direction
  P1REN |= 0xF0;                            // P1.4,5,6,7 pullup resistors
  P1OUT &= ~0x08;                           // Set P1.3 output to 'Lo' (RF 'OFF')
  P1IE |= 0xF0;                             // P1.4,5,6,7 interrupt enabled
  P1IES |= 0xF0;                            // P1.4,5,6,7 interrupt on Hi/lo edge
  P1IFG &= ~0xF0;                           // P1.4,5,6,7 IFG cleared

  __bis_SR_register(LPM3_bits + GIE);       // Enter LPM4 w/interrupt
}

        //Next will happen if level at any of P1.4,5,6,7 has fallen (button pressed)
#pragma vector=PORT1_VECTOR
__interrupt void Port_1(void)
{
        //Will stuck in this loop if you hold buttons pressed.
    while ((P1IN & 0xF0) != 0xF0)             //Is any button stay pressed?
    {
        command = ((P1IN>>4) ^ 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 "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(1500); P1OUT |= 0x08;    //"Space", 1.5mS
    __delay_cycles(500); P1OUT &= ~0x08;    //"Pulse", 0.5mS
    counter_st_pls--;
    }
        while (b)                           //Will be 'b' "DATA" pulses w/"Spaces"
        {
        __delay_cycles(500); P1OUT |= 0x08;     //"Space", 0.5mS
        __delay_cycles(500); P1OUT &= ~0x08;    //"Pulse", 0.5mS
        b--;
        }
}

/******************************************************************************/