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2.6
Manual Reset Operation
2.7
PCM Output Mode Configuration
2.7.1
Sampling Mode
Hardware Configuration
The PCM4222EVM includes two momentary-contact, normally open, push-button switches that are used
for manual reset functions. Switch SW4 can be used to reset the PCM4222, while switch SW5 can be
used to reset the DIT4192 transmitters. In each case, simply press and then release the corresponding
push-button switch to force an external reset for these devices.
The PCM4222 outputs linear encoded PCM data at the audio serial port output, header J6, or via the
DIT4192 AES3 transmitters. The PCM data is binary two’s complement, with the most significant bit of the
data transmitted first. The audio data word length may be 24, 20, 18, or 16 bits. Several audio formats are
supported. See section
(
) of this document and the
for
details.
The PCMEN input (pin 16) is used to enable and disable the PCM output mode.
summarizes the
operation of the PCMEN element on switch SW1. When the PCM output is disabled, the DATA (pin 32)
output is forced low. If the PCM4222 is set to Master mode, the BCK (pin 33) and LRCK (pin 34) clock
outputs are also forced low when the PCM output is disabled.
Table 5. PCM Output Mode Configuration
Switch SW1, PCMEN
PCM Output Mode
LO
PCM Output Disabled
HI
PCM Output Enabled
The PCM output operates in one three sampling modes: Normal, Double Speed, or Quad Speed. Normal
mode supports 128x oversampling with output sampling rates up to 54kHz. Double Speed mode supports
64x oversampling with output sampling rates from 54kHz to 108kHz. Quad Speed mode supports 32x
oversampling with output sampling rates from 108kHz to 216kHz.
The sampling mode is determined by the state of the FS0 and FS1 inputs (pins 19 and 20, respectively).
FS0 and FS1 are configured using the like named elements of switch SW1.
summarizes the
available settings for FS0 and FS1.
Table 6. PCM Sampling Mode Selection
Switch SW1, FS1
Switch SW1, FS0
PCM Sampling Mode
LO
LO
Normal
LO
HI
Double Speed
HI
LO
Quad Speed
HI
HI
Reserved
PCM4222EVM User's Guide
10
SBAU124 – December 2006