//******************************************************************************
// F2011 demo code for relaxation osc demo
//
// Version 0-00: 10-21-2006
//
//  Single key detection 
// This version determines if one of 4 keys has been pressed.  Base capacitance
// is tracked for changes and slider max endpoint is handled for no backoff
// or back in position detections.
//
// Testing using 3.5mm insulated keys. At 1MHz/8/512, ~50counts are achieved.
// Icc is ~57uA. Sensors are sampled ~16 times per second when a key is pressed;
// and ~3 times per second when no key is pressed after ~2 seconds. Current
// Consumption in this case is ~ 10uA.
//
// For demonstration, LEDs show finger position.
// Last "Key" maintains LED status
//
// Zack Albus
//******************************************************************************
#include  "msp430x20x1.h"

// Define User Configuration values //
//----------------------------------//
// Defines WDT SMCLK interval for sensor measurements
#define WDT_meas_setting (DIV_SMCLK_512)
// Defines WDT ACLK interval for delay between measurement cycles
#define WDT_delay_setting (DIV_ACLK_512)

// Sensor settings
#define Num_Sen     4                   // Defines number of sensors
#define KEY_lvl     25                  // Defines the min count for a "key press"
                                        // Set to ~ half the max delta expected

// Definitions for use with the WDT settings
#define DIV_ACLK_32768  (WDT_ADLY_1000)  /* ACLK/32768 */
#define DIV_ACLK_8192   (WDT_ADLY_250)   /* ACLK/8192 */
#define DIV_ACLK_512    (WDT_ADLY_16)    /* ACLK/512 */
#define DIV_ACLK_64     (WDT_ADLY_1_9)   /* ACLK/64 */
#define DIV_SMCLK_32768 (WDT_MDLY_32)    /* SMCLK/32768 */
#define DIV_SMCLK_8192  (WDT_MDLY_8)     /* SMCLK/8192 */
#define DIV_SMCLK_512   (WDT_MDLY_0_5)   /* SMCLK/512 */
#define DIV_SMCLK_64    (WDT_MDLY_0_064) /* SMCLK/64 */

// Define Hardware Inputs/Outputs
#define CA_Out  (0x80)                 // Comparator output on P1.7
#define CA_Ref  (0x02)                 // Comparator reference on P1.1
#define TA_Clk  (0x01)                 // Timer_A clock input on P1.0
#define Ref_En  (0x40)                 // External CA+ ref enable on P1.6

#define S_1   (0x04)                    // Sensor 1 P1.2
#define S_2   (0x08)                    // Sensor 2 P1.3
#define S_3   (0x10)                    // Sensor 3 P1.4
#define S_4   (0x20)                    // Sensor 4 P1.5

#define CA_1   (P2CA4)                  // Mux settings: CA+ Vref at CA1
#define CA_2   (P2CA2)                  // Mux settings: Sensor 1 at CA2
#define CA_3   (P2CA1+P2CA2)            // Mux settings: Sensor 2 at CA2
#define CA_4   (P2CA3)                  // Mux settings: Sensor 3 at CA2
#define CA_5   (P2CA1+P2CA3)            // Mux settings: Sensor 4 at CA2

#define LED_1   (0x80)                  // P2.7
#define LED_2   (0x40)                  // P2.6
#define BUZZ    (0x80)                  // Buzzer on P2.7

// Global variables for sensing
unsigned int base_cnt[Num_Sen];
unsigned int meas_cnt[Num_Sen];
int delta_cnt[Num_Sen];
unsigned char key_press[Num_Sen];
char key_pressed, key_loc;
int cycles;

// System Routines
void initialize(void);                  // Configure modules & control Registers
void measure_count(void);               // Measures each capacitive sensor
void pulse_LED(void);                   // LED gradient routine (for demo only)

// Main Function
void main(void)
{ volatile unsigned int i,j;

  WDTCTL = WDTPW + WDTHOLD;             // Stop watchdog timer
  BCSCTL1 = CALBC1_1MHZ;                // Set DCO to 1, 8, 12 or 16MHz
  DCOCTL = CALDCO_1MHZ;
  BCSCTL1 |= DIVA_0;                    // ACLK/(0:1,1:2,2:4,3:8)
  BCSCTL3 |= LFXT1S_2;                  // LFXT1 = VLO
  IE1 |= WDTIE;                         // enable WDT interrupt

  P1OUT = 0x00;                         // P1.x = 0
  P1DIR = 0xFE;                         // P1.0 = TACLK input
  P1SEL |= 0x81;                        // P1.0 = TACLK input, P1.7 = CAOUT
  P2OUT = 0x00;                         //
  P2DIR = LED_1 + LED_2;                // P2.6, P2.7 = outputs
  P2SEL = 0x00;                         // No XTAL

  CAPD =  CA_Ref;                       // disable input buffer for CA+ ref input
  CACTL2 = CA_1;                        // CA1 = CA+ Vref
  _EINT();                              // Enable interrupts

  P1OUT |= Ref_En;                      // Enable CA+ external reference
  measure_count();                      // Establish an initial baseline capacitance
  for (i = 0; i<Num_Sen; i++)
    base_cnt[i] = meas_cnt[i];

  for(i=15; i>0; i--)                   // Repeat and average base measurement
  { measure_count();
    for (j = 0; j<Num_Sen; j++)
      base_cnt[j] = (meas_cnt[j]+base_cnt[j])/2;
  }
  P1OUT &= ~Ref_En;                     // Disable CA+ external reference

  // Main loop starts here
  while (1)
  {
    key_pressed = 0;                    // Assume no keys are pressed

    measure_count();                    // Measure all sensors

    for (i = 0; i<Num_Sen; i++)
    { delta_cnt[i] = base_cnt[i] - meas_cnt[i];  // Calculate delta: c_change

      // Handle baseline measurment for a base C decrease
      if (delta_cnt[i] < 0)             // If negative: result increased
      {                                 // beyond baseline, i.e. cap decreased
          base_cnt[i] = (base_cnt[i]+meas_cnt[i]) >> 1; // Re-average baseline up quickly
          delta_cnt[i] = 0;             // Zero out delta for position determination
      }

      if (delta_cnt[i] > KEY_lvl)       // Determine if each key is pressed per a preset threshold
      {
        key_press[i] = 1;               // Specific key pressed
        key_pressed = 1;                // Any key pressed
      }
      else
        key_press[i] = 0;
    }

    // Delay to next sample, sample more slowly if no keys are pressed
    if (key_pressed)
    {
      BCSCTL1 = (BCSCTL1 & 0x0CF) + DIVA_0; // ACLK/(0:1,1:2,2:4,3:8)
      cycles = 20;
    }
    else
    {
      cycles--;
      if (cycles > 0)
        BCSCTL1 = (BCSCTL1 & 0x0CF) + DIVA_0; // ACLK/(0:1,1:2,2:4,3:8)
      else
      {
        BCSCTL1 = (BCSCTL1 & 0x0CF) + DIVA_3; // ACLK/(0:1,1:2,2:4,3:8)
        cycles = 0;
      }
    }
    WDTCTL = WDT_delay_setting;         // WDT, ACLK, interval timer

    // Handle baseline measurment for a base C increase
    if (!key_pressed)                   // Only adjust baseline down if no keys are touched
    {
      for (i = 0; i<Num_Sen; i++)
        base_cnt[i] = base_cnt[i] - 1;  // Adjust baseline down, should be slow to
    }                                   // accomodate for genuine changes in sensor C

    pulse_LED();

    LPM3;
  }
} // End Main

// Measure count result (capacitance) of each sensor
// Routine setup for four sensors, not dependent on Num_Sen value!
void measure_count(void)
{ char i;

  TACTL = TASSEL_0+MC_2;                // TACLK, cont mode
  TACCTL1 = CM_3+CCIS_2+CAP;            // Pos&Neg,GND,Cap

  P1OUT |= Ref_En;                      // Turn on CA ref ladder
  CACTL1 |= CAON;                       // Turn on comparator
  BCSCTL2 |= DIVS_3;                    // SMCLK = DCO/8, maximize counts

  for (i = 0; i<Num_Sen; i++)
  {
    switch (i)
    {
      case 0: // Sensor 1
              CAPD = CA_Ref+S_1;        // Diable I/Os for CA1 ref, 1st sensor
              CACTL2 = CA_1+CA_2;       // CA1 ref, CAx sensor
              break;
      case 1: // Sensor 2
              CAPD = CA_Ref+S_2;        // Diable I/Os for CA1 ref, 2nd sensor
              CACTL2 = CA_1+CA_3;       // CA1 ref, CAx sensor
              break;
      case 2: // Sensor 3
              CAPD = CA_Ref+S_3;        // Diable I/Os for CA1 ref, 3rd sensor
              CACTL2 = CA_1+CA_4;       // CA1 ref, CAx sensor
              break;
      case 3: // Sensor 4
              CAPD = CA_Ref+S_4;        // Diable I/Os for CA1 ref, 4th sensor
              CACTL2 = CA_1+CA_5;       // CA1 ref, CAx sensor
              break;
    }

    WDTCTL = WDT_meas_setting;          // Set duration of sensor measurment
    TACTL |= TACLR;                     // Clear Timer_A TAR
    LPM0;                               // Wait for WDT interrupt
    meas_cnt[i] = TACCR1;               // Save result
    WDTCTL = WDTPW + WDTHOLD;           // Stop watchdog timer
  }

  BCSCTL2 &= ~DIVS_3;                   // SMCLK = DCO

  // End Sequence
  P1OUT &= ~Ref_En;                     // Turn off CA ref ladder
  CACTL1 &= ~CAON;                      // Turn off comparator
  CAPD =  CA_Ref;                       // Re-init Mux: all sensors = GND
  CACTL2 = CA_1;                        // Only CA Ref connected
}

void pulse_LED(void)
{ char i;
  TACTL = TACLR;                        // SMCLK, up mode, int enabled
  TACCTL1 = CCIE;                       // interrupt enabled
  TACCR0 = 40001;                       // max leftover counts in one pass though of main
  TACCR1 = 40000;                       // time for led to be on

  if (key_pressed)
  {
    for (i = 0; i<Num_Sen; i++)
    {
      if (key_press[i])                 // key pressed?
        key_loc = i+1;
    }
  }

  switch (key_loc)
  {
    case 1: P2OUT = 0;
            TACCR1 = 1;
            break;
    case 2: P2OUT = LED_1;
            break;
    case 3: P2OUT = LED_2;
            break;
    case 4: P2OUT = LED_1 + LED_2;
            break;
    default:
            break;
  }

  TACTL = TACLR + TASSEL_2 + MC_1;      // SMCLK, up mode, int enabled
  _BIS_SR(LPM0_bits + GIE);             // Enter LPM0 w/ interrupt
  TACTL = TACLR;
  P2OUT &= ~(LED_1 + LED_2);
}

// Watchdog Timer interrupt service routine
#pragma vector=WDT_VECTOR
__interrupt void watchdog_timer(void)
{
  TACCTL1 ^= CCIS0;                     // Create SW capture of CCR1
  LPM3_EXIT;                            // Exit LPM3 on reti
}

// Timer A1 interrupt service routine
#pragma vector=TIMERA1_VECTOR
__interrupt void Timer_A1 (void)
{
    TACCTL1 &= ~CCIE;                   // interrupt disbled
    LPM0_EXIT;
}