Friends , I have to sample the input , every 14 microsecond in a 61 micro second slot with the timer input (Project Requirement).
I have to do it 8 times to make a byte. More like UART , but I am using it for One Wire Bus communication for my Masters Project.
I have written the code as below , which gives expected result, tested it executing one instruction at a time in debugger.
Below is the Code.
/*****************************************************************************
COMPARE MODE SAMPLING:
MCLK and SCLK @8MZ
The code configures P2.1 as TA1.CCI1A input.
It samples the input at P2.1 Whenever the TA1R reaches the TA1CCR1 value.
It samples input on P2.1 every 14us once in a duration of 61 us.
It then reads 8 bits one by one to read a byte.
******************************************************************************/
#include "io430g2553.h"
#define MSP_DQ BIT5
unsigned char word=0x00;
unsigned char i=0;
unsigned char temp;
void Read(void)
{
TA1CCR0 = 0x1E8; // 61 micro secs
TA1CCR1 = 0x70; // 14 micro secs
//TA0CCTL1 = CM_2 | CCIS_0 | SCS | CAP | OUTMOD_0 | CCIE;
//Keep in mind that It should not be configured as campture mode
TA1CCTL1 |= CM_2 | CCIS_0 | SCS | OUTMOD_0 | CCIE;
TA1CTL = TASSEL_2 + MC_1 + ID_0; // Register TA0CTL -> SMCLK/1, Up mode
do{
while ((TA1CCTL0 & CCIFG) == 0 ) // wait while CCIF is set
{
}
**TA1CCTL0 &= ~CCIFG; // Clear the flag** (%1%)
//TA1CTL &= ~TAIFG; // Clear the flag
i++;
} while( i<8) ;
TA1CTL = TACLR; // Stop the Timer
TA1CCTL1 = 0x00;
}
void Configure_CCI1A(void)
{
// Configuring P2.1 as TA1.CCI1A
P2OUT &= 0x00; // Clearing P1OUT
P2DIR &= ~BIT1 ; // Configuring P1.2 as input
P2SEL |= BIT1 ; // P2.1 Timer1_A, capture: CCI1A input, compare: Out1 output
P2SEL2 &= ~BIT1 ;
}
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
BCSCTL1 = CALBC1_8MHZ;
DCOCTL = CALDCO_8MHZ;
P1OUT &= 0x00; // Clearing P1OUT
P1DIR |= BIT0 ; // Configuring P1.0 as Output
__enable_interrupt();
Configure_CCI1A();
Read();
**P1OUT ^= BIT0;** //(%2%)
while(1) {
}
}
// Timer A1 interrupt service routine
#pragma vector=TIMER1_A1_VECTOR
__interrupt void Timer1_A1 (void)
{
P1OUT ^= BIT0; // To show Read occured
word <<=1; // If x = 00000010 (binary) => x <<= 2; => x=00001000
temp=0x00;
temp=((TA1CCTL1 & SCCI)>>10);
**word = word + temp ;** //(%3%)
}
But the issue is that when I call the function it some how appears stuck . I guess it is not coming out of the ISR cleanly though it completed all its execution when I run in debugger one instruction at a time. To make my question clear , This is how I tested :
Suppose if I put toggle break point at highlighted expression (%3%) in ISR , then it enters the ISR hits the togglebreak 8 times capturing correct values and comes out of Read Function neatly ( and also
while ((TA1CCTL0 & CCIFG) == 0 ) // wait while CCIF is set
{
}
and
{
....
....
i++;
} while( i<8) ;
out of above loop)
, to reach while(1) expression in the mains.
But instead if i put toggle point at the highlighted expression (%1%) it appears stuck. OR if I put the toggle break point directly at (%2%) in main what i expect , it to complete the Read function , store the value in word variable to reach the toggle break point but the code appears stuck and does not hit the togglebreak.
I do not know what is wrong, can any one please help ?
