This PCB handles the auxiliary input & headphone output.
SKT101 carries the headphone output from L117 (Analogue output). There is
also a switch to sense the headphones being inserted. The pullup resistor for
this is on L122, so if L127 PCB is not fitted or the cable not fitted, the unit will
sense the headphones are permanently inserted.
SKT100 is the microphone, auxillary input (to L116 Analogue input) & also
has an optical input for digital sources (Aux SPDIF to L115 Digital input) using
a 3.5mm optical lead.
This PCB handles the audio decoding of digital inputs & processing of
digitised analogue sources.
IC100 (ADSP-21366 DSP) handles the main decoding, including the new HD
formats. Data is either from I2S Data (SPDIF/ADC data from L115) or MCH
Data0, MCH Data1, MCH Data2, MCH Data3 from L122 (Main PCB). In both
cases, the clocks DSP WClk, DSPBClk & DSP MClk are required.
The code for IC100 is held in IC103 (S29AL016D FLASH). The DSP also
requires SRAM (IC101, IC104 71V424S SRAM). The address/data bus is
multiplexed through IC102 & IC106 (74LVC573 buffers) controlled by ALE.
Additional memory decoding is handled by IC105 (74LVC139 2-4 decoder).
R121 & R103 (0R0) should be fitted to allow the DSP to boot in SPI mode.
R117 (4k7) sets the internal clock multiplier to 16:1 (16*20MHz = 320MHz).
IC201 (ADSP-21367 DSP) handles the post-processing & room EQ. Data is
sent in multichannel format regardless of the input between IC100 & IC201
(DSP2 LR, DSP2 LsRs, DSP2 CSw, DSP2 SblSbr). The data is clocked in
using DSP2 BClk & DSP2 WClk, generated by IC100 & DSP MClk from L121.
Data is then clocked out to the DACs (Data LR, Data SlSr, Data CSw, Data
SblSbr) with clocks DSP BClk Out, DSPWClk Out which are buffered on L121
before going to L117 (Analogue Out).
Communication with the PW338 is via a single SPI bus:
DSP Clk - clock
DSP MISO – data from PW338
DSP MOSI – data to the PW338
DSP1 /CS – select DSP1
DSP2 /CS – select DSP2
DSP1 FLAG0 – signal back to PW338
DSP2 FLAG0 – signal back to the PW338
Note: DSP reset is by asserting both /CS lins low simultaneously (IC107
74LV1G32 single Or gate).
L127AY Front Input
L156AY – DSP board
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