Cirrus Logic CS8420 - Manual (Page 37)

DS245F4 37
CS8420
10.5 Clock Source Control (04h)
This register configures the clock sources of various blocks. In conjunction with the Data Flow
Control register, various Receiver/Transmitter/Transceiver modes may be selected.
RUN The RUN bit controls the internal clocks, allowing the CS8420 to be placed in a
“powered down”, low current consumption, state.
0 - Internal clocks are stopped. Internal state machines are reset. The fully static
control port is operational, allowing registers to be read or changed. Reading and
writing the U and C data buffers is not possible. Power consumption is low (default).
1 - Normal part operation. This bit must be written to the 1 state to allow the CS8420
to begin operation. All input clocks should be stable in frequency and phase when
RUN is set to 1.
CLK[1:0] Output side master clock input (OMCK) frequency to output sample rate (Fso) ratio selector. If
these bits are changed during normal operation, then always stop the CS8420 first (RUN = 0),
then write the new value, then start the CS8420 (RUN = 1).
00 - OMCK frequency is 256*Fso(default)
01 - OMCK frequency is 384*Fso
10 - OMCK frequency is 512*Fso
11 - reserved
OUTC Output Time Base
0 - OMCK input pin (modified by the selected divide ratio bits CLK1 & CLK0,
(default)
1 - Recovered Input Clock
INC Input Time Base Clock Source
0 - Recovered Input Clock (default)
1 - OMCK input pin (modified by the selected divide ratio bits CLK1 & CLK0)
RXD[1:0] Recovered Input Clock Source
00 - 256*Fsi, where Fsi is derived from the ILRCK pin (only possible when the
serial audio input port is in Slave mode, default)
01 - 256*Fsi, where Fsi is derived from the AES3 input frame rate
10 - Bypass the PLL and apply an external 256*Fsi clock via the RMCK pin. The AES3
receiver is held in synchronous reset. This setting is useful to prevent UNLOCK
interrupts when using an external RMCK and inputting data via the serial audio
input port.
11 - Reserved
7 6 5 4 3 2 1 0
0 RUN CLK1 CLK0 OUTC INC RXD1 RXD0