ADSP-2126x SHARC Processor Hardware Reference
12-9
Digital Audio Interface
While the pin is high impedance and another device is driving a logic level
onto the external pin, this value is sent to the SRU as the pin interface
output. Even though the signal is an input to the processor, it is an output
from the pin interface (as a three-terminal device) and may be patched to
the signal inputs of peripherals within the SRU. Pin output is equal to pin
input when the pin enable is asserted, but pin output is equal to the exter-
nal (input) signal when the pin enable is deasserted.
If a DAI pin is not being used, the pin enable (
DAI_PBxx_I
) for its
pin buffer should be connected to
LOW
and its associated bit in the
DAI_PIN_PULLUP
register should be set (= 1) to enable a pull-up
resistor for that pin.
Pin Buffers as Signal Output Pins
In a typical embedded system, most pins are designated as either inputs or
outputs when the circuit is designed, even if they may have the ability to
be used in either direction. Each of the DAI pins can be used as either an
output or an input. Although the direction of a DAI pin is set simply by
writing to a memory-mapped register, most often the pin’s direction is
Figure 12-6. Input Signal from Off-chip Drives Pin Output when Pin is
not Enabled
IN
OUT
PIN
ENABLE
PBxx_I
PBxx_O
PINENxx_I
EXTERNAL
PACKAGE
CONNECTION
PIN
INTERFACE
TO SRU
PBxx_O
PAD
DRIVER
Summary of Contents for ADSP-21261 SHARC
Page 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Page 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Page 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Page 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Page 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Page 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Page 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Page 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Page 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Page 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Page 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Page 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...