CMX983 Datasheet, PDF (47/93 Pages) CML Microcircuits – Programmable Channel Filter

Analogue Front End (AFE) for Digital Radio
11.2 Tx Serial Port
CMX983
Figure 18 Tx Serial Port
Data for Tx channel A and B are input to the CMX983 through a PCM serial port (Figure 18). PCM data is
sent in Short Frame Sync mode with the CMX983 acting as a master. The PCM clock TXCLK is divided down
from the system clock CLK, and data transmission is most significant bit first. If both Tx Channel A and B are
selected, the two 16-bit data words are multiplexed through a single input data pin TXD as shown in Figure
19. If only one of the two Tx channels is selected, then the 16-bit serial port shift register for the disabled
channel is bypassed and only the data for the selected channel is shifted in (example shown in Figure 20).
t_{CYC_TXCLK}
TXCLK
TXFS
t_{CYC_TXFS}
TXD
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Channel A data
Channel B data
15 14 13
Figure 19 Tx Port Timing (Channel A and B both selected)
t_{CYC_TXCLK}
TXCLK
TXFS
t_{CYC_TXFS}
TXD
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Channel B data
15 14 13
 2015 CML Microsystems Plc
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