DT512 timer-delay calculation

changebusclock — Thu, 12 Mar 2009 17:24:05 GMT

I want to know whether i am correct in calculating the delay value...

My program goes this way

TSCR1=0x90//timer enable,fast clear flag enable.

TIOS_IOS0=1;

TSCR2=0x07;//PRESCALAR=128

TCTL2=0x01;

TFLG1_C0F=1;

TC0=0x124F;// FOR 300ms DELAY.....

while(!TFLG1_C0F);//waiting for timer to complete......

CALCULATION

count*time period = delay

=> count=300ms/timeperiod

=300ms/(128/2MHz)

=0x124f

Should i load 0x124f to TC0 or should i load (oxffff-0x124f) into TC0 to obtain 300millisecond delay...

Re: DT512 timer-delay calculation

kef — Fri, 13 Mar 2009 21:57:58 GMT

TSCR1=0x90//timer enable,fast clear flag enable.
TIOS_IOS0=1;
TSCR2=0x07;//PRESCALAR=128
TCTL2=0x01;

TFLG1_C0F=1;

Keep in mind that this ^^ line clears all 8 timer flags, not just TC0 flag.

TFLG1 = TFLG1_C0F_MASK; or TFLG1 &= TFLG1_C0F_MASK; will clear just TC0 flag.

Also, having fast flag clear enabled, writing one to timer flag may not work, you should check the datasheet.

TC0=0x124F;// FOR 300ms DELAY.....
while(!TFLG1_C0F);//waiting for timer to complete......

Your code depends on what is current free running TCNT counter value. It will wait until TCNT counter reaches TCNT=TC0. To wait for 0x124F timer ticks, you should assign TCNT+0x124F to TC0. Or, if you want to delay by 0x124F ticks from previous TC0 compare event, then TC0=TC0+0x124F.

CALCULATION
count*time period = delay
=> count=300ms/timeperiod
=300ms/(128/2MHz)
=0x124f

Should i load 0x124f to TC0 or should i load (oxffff-0x124f) into TC0 to obtain 300millisecond delay...

Do you have 2MHz bus clock? Then 0x124f is OK, but you should add starting TCNT value.

S12 / MagniV MicrocontrollersのトピックRe: DT512 timer-delay calculation

DT512 timer-delay calculation

Re: DT512 timer-delay calculation