Texas Instruments Incorporated

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GC1012B 3.3V DIGITAL TUNER

SLWS138B

This document contains information which may be changed at any time without notice

3.5

OUTPUT MODE REGISTER

The output mode register controls the output formatting.

ADDRESS 8:

Output mode register

BIT

TYPE

NAME

DESCRIPTION

0

R/W

IQ_MUX

The IQ_MUX control is used in the complex mode to multiplex the I and Q output

words onto the I[0:15] output pins. Normally the I and Q halves are output on

separate ports. When this bit is high, the halves are multiplexed together so that

the I half is output first, followed by the Q half. The word strobe (WS) rate is doubled

in this mode. The IFLAG output signal is used in this mode to identify the I half of

each complex pair. The Q[0:15] output pins are forced low in this mode.

1

R/W

WS_POL

Changes the polarity of WS.

2

R/W

WS_MODE

Changes the mode of WS. Normally WS pulses high during the clock cycle before

an I or Q output transition. This bit changes WS so that it is a 50% duty cycle clock

with its rising edge in the middle of each output period

3

R/W

-

Unused

4

R/W

R10

Round the output samples to the 10 bits MSBs of the output word.

5

R/W

R12

Round the output samples to the 12 bits MSBs of the output word.

6

R/W

R14

Round the output samples to the 14 bits MSBs of the output word.

7

R/W

R16

Round the output samples to the 16 bits MSBs of the output word.

One and only one of the rounding options should be selected. Unused LSBs are cleared.

The IQ_MUX and WS_MODE controls are illustrated in the timing diagrams shown in Figure 5. Note

that the polarity shown for WS can be changed using the WS_POL control.

Figure 5. Timing For Output Modes

DECIMATE BY 2 MODE: (DEC=2)

CK

IFLAG

DECIMATE BY 4 MODE: (DEC=3)

CK

I or Q

WS

(WS_MODE= 0)

WS

I or Q

WS

(WS_MODE= 0 or 1)

DECIMATE BY 2 MODE WITH IQ_MUX, OR REAL MODES: (DEC=2, REAL=1 OR IQ_MUX=1)

CK

I

(Q is low, WS is high)

DECIMATE BY 4 MODE WITH IQ_MUX OR REAL MODES: (DEC=2, REAL=1 OR IQ_MUX=1)

CK

I or Q

WS

(WS_MODE= 0 or 1)

IFLAG