DS90UB925Q-Q1 Datasheet, PDF (20/51 Pages) Texas Instruments – 5 to 85 MHz 24-Bit Color FPD-Link III Serializer With Bidirectional Control Channel

DS90UB925Q-Q1
SNLS407D – APRIL 2012 – REVISED OCTOBER 2014
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7.3.17.1 Secondary I2S Channel
In I2S Channel B operation mode, the secondary I2S data (I2S_DB) can be used as the additional I2S audio in
addition to the 3–bit of I2S. The I2S_DB input must be synchronized to I2S_CLK and aligned with I2S_DA and
I2S_WC at the input to the serializer. This operation mode is enabled through either the MODE_SEL pin
(Table 4) or through the register bit 0x12[0] (Table 6).
Table 3 covers the range of I2S sample rates.
SAMPLE RATE (kHz)
32
44.1
48
96
192
32
44.1
48
96
192
32
44.1
48
96
192
Table 3. Audio Interface Frequencies
I2S DATA WORD SIZE (BITS)
16
16
16
16
16
24
24
24
24
24
32
32
32
32
32
I2S CLK (MHz)
1.024
1.411
1.536
3.072
6.144
1.536
2.117
2.304
4.608
9.216
2.048
2.822
3.072
6.144
12.288
7.3.18 Built In Self Test (BIST)
An optional At-Speed Built In Self Test (BIST) feature supports the testing of the high speed serial link and the
low- speed back channel. This is useful in the prototype stage, equipment production, in-system test and also for
system diagnostics. Note: BIST is not available in backwards compatible mode.
7.3.18.1 BIST Configuration and Status
The BIST mode is enabled at the deseralizer by the Pin select (Pin 44 BISTEN and Pin 16 BISTC) or
configuration register (Table 6) through the deserializer. When LFMODE = 0, the pin based configuration defaults
to external PCLK or 33 MHz internal Oscillator clock (OSC) frequency. In the absence of PCLK, the user can
select the desired OSC frequency (default 33 MHz or 25MHz) through the register bit. When LFMODE = 1, the
pin based configuration defaults to external PCLK or 12.5MHz MHz internal Oscillator clock (OSC) frequency.
When BISTEN of the deserializer is high, the BIST mode enable information is sent to the serializer through the
Back Channel. The serializer outputs a test pattern and drives the link at speed. The deserializer detects the test
pattern and monitors it for errors. The PASS output pin toggles to flag any payloads that are received with 1 to
35 bit errors.
The BIST status is monitored real time on PASS pin. The result of the test is held on the PASS output until reset
(new BIST test or Power Down). A high on PASS indicates NO ERRORS were detected. A Low on PASS
indicates one or more errors were detected. The duration of the test is controlled by the pulse width applied to
the deserializer BISTEN pin. This BIST feature also contains a Link Error Count and a Lock Status. If the
connection of the serial link is broken, then the link error count is shown in the register. When the PLL of the
deserializer is locked or unlocked, the lock status can be read in the register. See Table 6.
7.3.18.1.1 Sample BIST Sequence
See Figure 13 for the BIST mode flow diagram.
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