Rev. C
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Page 13 of 76
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July 2013
The watch dog timer also has an internal RC oscillator that can
be used as the clock source. The internal RC oscillator can be
used as an optional alternative to using an external clock applied
to the WDT_CLIN pin.
Real-Time Clock
The real-time clock (RTC) provides a robust set of digital watch
features, including current time, stopwatch, and alarm. The
RTC is clocked by a 32.768 kHz crystal external to the SHARC
processor. Connect RTC pins RTXI and RTXO with external
The RTC peripheral has dedicated power supply pins so that it
can remain powered up and clocked even when the rest of the
processor is in a low power state. The RTC provides several pro-
grammable interrupt options, including interrupt per second,
minute, hour, or day clock ticks, interrupt on programmable
stopwatch countdown, or interrupt at a programmed alarm
time. An RTCLKOUT signal that operates at 1 Hz is also pro-
vided for calibration.
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 60-second counter, a 60-minute counter, a
24-hour counter, and a 32,768-day counter. When the alarm
interrupt is enabled, the alarm function generates an interrupt
when the output of the timer matches the programmed value in
the alarm control register. There are two alarms: The first alarm
is for a time of day. The second alarm is for a day and time of
that day.
The stopwatch function counts down from a programmed
value, with one-second resolution. When the stopwatch inter-
rupt is enabled and the counter underflows, an interrupt is
generated.
SYSTEM DESIGN
The following sections provide an introduction to system design
options and power supply issues.
Program Booting
The internal memory boots at system power-up from an 8-bit
EPROM via the external port, an SPI master, or an SPI slave.
Booting is determined by the boot configuration
A running reset feature is used to reset the processor core and
peripherals without resetting the PLL and SDRAM controller,
or performing a boot. The functionality of the RESETOUT
/RUNRSTIN pin has now been extended to also act as the input
for initiating a running reset. For more information, see the
ADSP-214xx SHARC Processor Hardware Reference.
Power Supplies
The processors have separate power supply connections for the
internal (VDD_INT) and external (VDD_EXT) power supplies. The
internal and analog supplies must meet the VDD_INT specifica-
tions. The external supply must meet the VDD_EXT specification.
All external supply pins must be connected to the same power
supply.
To reduce noise coupling, the PCB should use a parallel pair of
power and ground planes for VDD_INT and GND.
Target Board JTAG Emulator Connector
Analog Devices DSP Tools product line of JTAG emulators uses
the IEEE 1149.1 JTAG test access port of the processors to mon-
itor and control the target board processor during emulation.
Analog Devices DSP Tools product line of JTAG emulators pro-
vides emulation at full processor speed, allowing inspection and
modification of memory, registers, and processor stacks. The
processor's JTAG interface ensures that the emulator will not
affect target system loading or timing.
For complete information on Analog Devices’ SHARC DSP
Tools product line of JTAG emulator operation, see the appro-
priate emulator hardware user’s guide.
DEVELOPMENT TOOLS
Analog Devices supports its processors with a complete line of
software and hardware development tools, including integrated
development environments (which include CrossCore
Embed-
ded Studio and/or VisualDSP++
), evaluation products,
emulators, and a wide variety of software add-ins.
Integrated Development Environments (IDEs)
For C/C++ software writing and editing, code generation, and
debug support, Analog Devices offers two IDEs.
The newest IDE, CrossCore Embedded Studio, is based on the
Eclipse
TM framework. Supporting most Analog Devices proces-
sor families, it is the IDE of choice for future processors,
including multicore devices. CrossCore Embedded Studio
Figure 3. External Components for RTC
RTXO
C1
C2
X1
NOTE: C1 AND C2 ARE SPECIFIC TO CRYSTAL SPECIFIED FOR X1.
CONTACT CRYSTAL MANUFACTURER FOR DETAILS. C1 AND C2
SPECIFICATIONS ASSUME BOARD TRACE CAPACITANCE OF 3 pF.
RTXI
R1
Table 10. Boot Mode Selection
BOOT_CFG2–0
1
Booting Mode
000
SPI Slave Boot
001
SPI Master Boot (from Flash and Other Slaves)
010
AMI User Boot (for 8-bit Flash Boot)
011
No Boot (Processor Executes from Internal
ROM After Reset)
100
Reserved
1xx
Reserved
1 The BOOT_CFG2 pin is not available on the 100-lead or 88-lead packages.