Watchdog Timer
1-16
ADSP-BF535 Blackfin Processor Hardware Reference
The 32.768 kHz input clock frequency is divided down to a 1 Hz signal
by a prescaler. The counter function of the timer consists of four counters:
a 6-bit second counter, a 6-bit minute counter, a 5-bit hours counter, and
an 8-bit day counter.
When enabled, the alarm function generates an interrupt when the output
of the timer matches the programmed value in the alarm control register.
The stopwatch function counts down from a programmed value, with one
minute resolution. When the stopwatch is enabled and the counter under-
flows, the allotted time has expired and an interrupt is generated.
Like the other peripherals, the RTC can wake up the ADSP-BF535 pro-
cessor from a low power state upon generation of any interrupt.
Watchdog Timer
The ADSP-BF535 processor includes a 32-bit timer, which can be used to
implement a software watchdog function. A software watchdog can
improve system availability by forcing the processor to a known state, via
generation of a hardware reset, non-maskable interrupt (NMI), or
general-purpose interrupt, if the timer expires before being reset by soft-
ware. The programmer initializes the count value of the timer, enables the
appropriate interrupt, then enables the timer. Thereafter, the software
must reload the counter before it counts to zero from the programmed
value. This protects the system from remaining in an unknown state
where software, which would normally reset the timer, has stopped run-
ning due to an external noise condition or software error.
If configured to generate a hardware reset, the timer can be programmed
to reset only the ADSP-BF535 CPU, or both the CPU and the
ADSP-BF535 peripherals. After a reset, software can determine if the
watchdog was the source of the hardware reset by interrogating a status bit
in the timer control register, which is set only upon a watchdog generated
reset.
Summary of Contents for ADSP-BF535 Blackfin
Page 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Page 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Page 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Page 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Page 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Page 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Page 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Page 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Page 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Page 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Page 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Page 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Page 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...