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Programming Examples
15-58
ADSP-BF537 Blackfin Processor Hardware Reference
Since hardware only updates the written period and width values at the
end of periods, software can write new values immediately after the timers
have been enabled. Note that both timers’ period expires at exactly the
same times with the exception of the first timer 5 interrupt (at
IRQ1
)
which is not visible to timer 4.
Listing 15-5. Non-Overlapping Clock Pulses
#define P 0x1000 /* signal period */
#define W 0x0600 /* signal pulse width */
#define N 4 /* number of pulses before disable */
timer45_toggle_hi:
[--sp] = (r7:1, p5:5);
p5.h = hi(TIMER_ENABLE);
p5.l = lo(TIMER_ENABLE);
/* config timers */
r7.l = IRQ_ENA | PERIOD_CNT | TOGGLE_HI | PULSE_HI | PWM_OUT;
w[p5 + TIMER5_CONFIG - TIMER_ENABLE] = r7;
r7.l = PERIOD_CNT | TOGGLE_HI | PULSE_HI | PWM_OUT;
w[p5 + TIMER4_CONFIG - TIMER_ENABLE] = r7;
/* calculate timers widths and period */
r0.l = lo(P);
r0.h = hi(P);
r1.l = lo(W);
r1.h = hi(W);
r2 = r1 >> 1; /* W/2 */
r3 = r0 >> 1; /* P/2 */
r4 = r3 - r2; /* P/2 - W/2 */
r5 = r0 - r2; /* P - W/2 */
/* write values for initial period */
[p5 + TIMER4_PERIOD - TIMER_ENABLE] = r0;
[p5 + TIMER4_WIDTH - TIMER_ENABLE] = r5;
[p5 + TIMER5_PERIOD - TIMER_ENABLE] = r3;
[p5 + TIMER5_WIDTH - TIMER_ENABLE] = r4;
Содержание Blackfin ADSP-BF537
Страница 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...