PinOsc signal feed into TA0CLK.. WDT interval is used // to gate the measurements.. Difference in measurements indicate button touch.. // LEDs flash if input is touched.
Trang 1//****************************************************************************** // MSP430G2xx2 Demo - Capacitive Touch, Pin Oscillator Method, 4-buttons
//
// Description: Basic 4-button input using the built-in pin oscillation feature // on GPIO input structure PinOsc signal feed into TA0CLK WDT interval is used
// to gate the measurements Difference in measurements indicate button touch // LEDs flash if input is touched
//
// Input 1: LED1 (LED2 off)
// Input 2: LED2 (LED1 off)
// Input 3: Both LEDs on
// Input 4: Both LEDs flash on/off
//
// ACLK = VLO = 12kHz, MCLK = SMCLK = 1MHz DCO
//
// MSP430G2xx2
//
-// /|\|
XIN|-// | | |
// |RST
XOUT|-// | |
// | P1.1|< Capacitive Touch Input 1
// | |
// LED 2 < |P1.6 P1.2|< Capacitive Touch Input 2
// | |
// LED 1 < |P1.0 P1.4|< Capacitive Touch Input 3
// | |
// | P1.5|< Capacitive Touch Input 4
//
// Brandon Elliott/D Dang
// Texas Instruments Inc
// November 2010
// Built with IAR Embedded Workbench Version: 5.10
//******************************************************************************
#include "msp430g2452.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 220 // Defines threshold 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 LED_1 (0x01) // P1.0 LED output
Trang 2#define LED_2 (0x40) // P1.6 LED output
// 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;
int cycles;
const unsigned char electrode_bit[NUM_SEN]={BIT1, BIT2, BIT4, BIT5};
/* System Routines*/
void measure_count(void); // Measures each capacitive sensor void pulse_LED(void); // LED gradient routine
/* Main Function*/
void main(void)
{
unsigned int i,j;
WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer
BCSCTL1 = CALBC1_1MHZ; // Set DCO to 1MHz
DCOCTL = CALDCO_1MHZ;
BCSCTL3 |= LFXT1S_2; // LFXT1 = VLO
IE1 |= WDTIE; // enable WDT interrupt
P2SEL = 0x00; // No XTAL
P1DIR = LED_1 + LED_2; // P1.0 & P1.6 = LEDs
P1OUT = 0x00;
bis_SR_register(GIE); // Enable interrupts
measure_count(); // Establish baseline capacitance for (i = 0; i<NUM_SEN; i++)
base_cnt[i] = meas_cnt[i];
for(i=15; i>0; i ) // Repeat and avg base measurement {
measure_count();
for (j = 0; j<NUM_SEN; j++)
base_cnt[j] = (meas_cnt[j]+base_cnt[j])/2;
}
/* Main loop starts here*/
while (1)
{
j = KEY_LVL;
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 dec base_cnt[i] = (base_cnt[i]+meas_cnt[i]) >> 1; // Re-average quickly delta_cnt[i] = 0; // Zero out for pos determination }
if (delta_cnt[i] > j) // Determine if each key is pressed { // per a preset threshold
key_press[i] = 1; // Specific key pressed
Trang 3j = delta_cnt[i];
key_pressed = i+1; // 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 pulse_LED(); // changes in sensor C
bis_SR_register(LPM3_bits);
}
} // 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;
TA0CTL = TASSEL_3+MC_2; // TACLK, cont mode
TA0CCTL1 = CM_3+CCIS_2+CAP; // Pos&Neg,GND,Cap
for (i = 0; i<NUM_SEN; i++)
{
/*Configure Ports for relaxation oscillator*/
/*The P2SEL2 register allows Timer_A to receive it's clock from a GPIO*/ /*See the Application Information section of the device datasheet for info*/ P1DIR &= ~ electrode_bit[i];
P1SEL &= ~ electrode_bit[i];
P1SEL2 |= electrode_bit[i];
/*Setup Gate Timer*/
WDTCTL = WDT_meas_setting; // WDT, ACLK, interval timer
TA0CTL |= TACLR; // Clear Timer_A TAR
bis_SR_register(LPM0_bits+GIE); // Wait for WDT interrupt
TA0CCTL1 ^= CCIS0; // Create SW capture of CCR1
Trang 4meas_cnt[i] = TACCR1; // Save result
WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer
P1SEL2 &= ~electrode_bit[i];
}
}
void pulse_LED(void)
{
switch (key_pressed){
case 0: P1OUT &= ~(LED_1 + LED_2);
break;
case 1: P1OUT = LED_1;
break;
case 2: P1OUT = LED_2;
break;
case 3: P1OUT = LED_1 + LED_2;
break;
case 4: P1OUT ^= LED_1 + LED_2;
break;
}
}
/* Watchdog Timer interrupt service routine*/
#pragma vector=WDT_VECTOR
interrupt void watchdog_timer(void)
{
TA0CCTL1 ^= CCIS0; // Create SW capture of CCR1 bic_SR_register_on_exit(LPM3_bits); // Exit LPM3 on reti
}