RTC Programming Model
18-8
ADSP-BF537 Blackfin Processor Hardware Reference
interrupt. Software does not have to wait for writes to one RTC MMR to
complete before writing to another RTC MMR. The write pending status
bit is set if any writes are in progress, and the write complete flag is set
only when all writes are complete.
a
Any writes in progress when peripherals are reset are aborted. Do
not stop
SCLK
(enter deep sleep mode) or remove Internal V
dd
power until all RTC writes have completed.
Do not attempt another write to the same register without waiting
for the previous write to complete. Subsequent writes to the same
register are ignored if the previous write is not complete.
Reading a register that has been written before the write complete
flag is set will return the old value. Always check the write pending
status bit before attempting a read or write.
Write Latency
Writes to the RTC MMRs are synchronized to the 1 Hz RTC clock.
When setting the time of day, do not factor in the delay when writing to
the RTC MMRs. The most accurate method of setting the RTC is to
monitor the seconds (1 Hz) event flag or to program an interrupt for this
event and then write the current time to the RTC status register
(
RTC_STAT
) in the interrupt service routine (ISR). The new value is
inserted ahead of the incrementer. Hardware adds one second to the writ-
ten value (with appropriate carries into minutes, hours and days) and
loads the incremented value at the next 1 Hz tick, when it represents the
then-current time.
Writes posted at any time are properly synchronized to the 1 Hz clock.
Writes complete at the rising edge of the 1 Hz clock. A write posted just
before the 1 Hz tick may not be completed until the 1 Hz tick one second
later. Any write posted in the first 990 ms after a 1 Hz tick completes on
the next 1 Hz tick, but the simplest, most predictable and recommended
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...