
ADSP-214xx SHARC Processor Hardware Reference
23-35
System Design
Pull-Up/Pull-Down Resistors
The pin descriptions in the product specific data sheets includes recom-
mendations on how to handle pins on interfaces that are disabled or for
unused pins on interfaces that are enabled. Generally, if internal pull-ups
(PU) or pull-downs (PD) are included, the pins can be left floating. Any
pin that is output only can always be left floating.
If internal pull-ups and pull-downs are not included or disabled, pins can
normally still be floated with no functional issues for the device. However,
this may allow additional leakage current.
Although the recommendations normally indicate using external pull-up
resistors, pull-down resistors can also be used. The leakage is the same
whether pull-ups or pull-downs are used. Connections directly to power
or ground can be used only if the pins can be guaranteed to never be con-
figured as outputs.
Memory Select Pins
When the multiplexed memory selects,
MS3-2
, are enabled as outputs, the
pull-up resistors are automatically enabled. For example, if
MS2
and
MS3
are used, they require that stronger external pull-up resistors are
connected. For more details on resistor values, refer to the product specific
data sheet.
Edge-Triggered I/O
It is recommended that GPIO output pins that are used to drive an
edge-sensitive signal like an interrupt (
IRQ2-0
, DAI/DPI pins) have series
termination resistors to prevent glitches on the signal transitions. It is
equally important that GPIO inputs that are edge-sensitive be driven from
sources that have series termination resistors. The values for the series
resistor can be determined by simulating with the IBIS models. These
models can be found on the Analog Devices web site.
www.BDTIC.com/ADI
Summary of Contents for SHARC ADSP-214 Series
Page 60: ...Contents lx ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 72: ...Notation Conventions lxxii ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 130: ...Programming Model 2 52 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 264: ...Programming Models 3 134 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 290: ...Programming Model 4 26 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 296: ...Programming Model 5 6 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 396: ...Effect Latency 7 28 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 520: ...Programming Model 10 62 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 656: ...Programming Model 15 40 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 714: ...Programming Model 19 10 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...