Hi,
I need a Timer based delay functions and wrote the followings.
(msp430F5529; CCS Version: 5.3.0.00090; FET430UIF; XTAL1 32768Hz ; XTAL2 4MHz)
int main(void)
{
WDTCTL = WDTPW | WDTHOLD; // Stop watchdog timer
// Basic GPIO initialization
Board_init();
// Set Vcore to accomodate for max. allowed system speed
SetVCore(3);
// Use 32.768kHz XTAL as reference
LFXT_Start(XT1DRIVE_0);
// Set system clock to max (25MHz)
Init_FLL_Settle(25000, 762);
SFRIFG1 = 0;
SFRIE1 |= OFIE;
Clear_Int16_Flag(StatusFlag_1,AllFlags);
Set_Int16_Flag(StatusFlag_1,PowerMode);
Set_Int16_Flag(StatusFlag_1,ShowRtcOnLCD);
*ActiveModeTimeout = 10;
TimeOut_Us=0;
TimeOut_Ms=0;
// Globally enable interrupts
__enable_interrupt();
Test_Delay();
while(1)
{….
// Timer0 A0 interrupt service routine
#pragma vector=TIMER0_A0_VECTOR
__interrupt void TIMER0_A0_ISR(void)
{
if(TimeOut_Us)
{
TimeOut_Us--;
}
else if(TimeOut_Ms)
{
TimeOut_Ms--;
}
else
{
Set_Int16_Flag(StatusFlag_1,TimerTimeOut);
TA0CCTL0 &= ~CCIE;
}
}
void Test_Delay (void)
{
uint32_t i;
for(i =0 ;i<10000;i++)
{
CLK_HIGH;
Delay_10Us(1);
CLK_LOW;
Delay_10Us(1);
}
for(i =0 ;i<1000;i++)
{
CLK_HIGH;
Delay_Ms(1);
CLK_LOW;
Delay_Ms(1);
}
for(i =0 ;i<6;i++)
{
CLK_HIGH;
Delay_s(1);
CLK_LOW;
Delay_s(1);
}
}
void Delay_10Us(uint32_t Time)
{
TimeOut_Us=Time;
TimeOut_Ms=0;
TA0CCTL0 = CCIE; // CCR0 interrupt enabled
TA0CCR0 = 250;
TA0CTL = TASSEL_2 + MC_1 + TACLR; // SMCLK, upmode, clear TAR
while(!Status_Int16_Flag(StatusFlag_1,TimerTimeOut));
Clear_Int16_Flag(StatusFlag_1,TimerTimeOut);
}
void Delay_Ms(uint32_t Time)
{
TimeOut_Us=0;
TimeOut_Ms=Time;
TA0CCTL0 = CCIE; // CCR0 interrupt enabled
TA0CCR0 = 25000;
TA0CTL = TASSEL_2 + MC_1 + TACLR; // SMCLK, upmode, clear TAR
while(!Status_Int16_Flag(StatusFlag_1,TimerTimeOut));
Clear_Int16_Flag(StatusFlag_1,TimerTimeOut);
}
void Delay_s(uint32_t Time)
{
TimeOut_Us=0;
TimeOut_Ms=Time*1000;
TA0CCTL0 = CCIE; // CCR0 interrupt enabled
TA0CCR0 = 25000;
TA0CTL = TASSEL_2 + MC_1 + TACLR; // SMCLK, upmode, clear TAR
while(!Status_Int16_Flag(StatusFlag_1,TimerTimeOut));
Clear_Int16_Flag(StatusFlag_1,TimerTimeOut);
}
And I got the following results.
The UCS register that I copy at run time are in debug mode;
0x000160 --> 10F0 0060 117C 0000 0033 0000 C10D 0C10 0707 0000 0000
From SLAU208M–June 2008 document chapter 5, page 164 I got the formula as;
fDCOCLK = D × (N + 1) × (fFLLREFCLK ÷ n)
As seen form the register my;
D -> FLLD = 2
N+1 -> FLLN+1 = 381
fFLLREFCLK -> Xtal1 = 32768 (I mentioned at the top)
n -> FLLREFDIV = 1
Fdco = 2x381(32768/1)= 24969216 =~ 25 Mhz, and SMCLK source is DCOCLK (SELS = 011b)
I couldn’t understand why I got the result two times longer than I expected in Delay_10Us() and Delay_Ms() routines but not in Delay_s() ?
Thanks and Kind regards.
