GC1012A Datasheet, PDF (7/30 Pages) Texas Instruments – DIGITAL TUNER CHIP

GC1012A DIGITAL TUNER
DATA SHEET REV 0.1
1.2 BLOCK DIAGRAM
A block diagram illustrating the major functions of the chip is shown in Figure 1
X
(12 BITS)
DIAG-
NOSTIC
RAMP
PROGRAMMABLE
LOW PASS
FILTER
COS
SIN
DIGITAL
OSCILLATOR
GAIN
ADJUST
DIAG
SELECT
FREQ
BANDWIDTH
GAIN
OUTPUT
FORMAT
I
OUTPUTS
(10,12,14, OR 16 BITS)
Q
STROBES
(WS,IFLAG)
CHECKSUM
REAL,
FLIP
AND
OFFSET
OPTIONS
I/Q
SAMPLES
CHECKSUM
SYNCS IN
SS,AS,GS)
CONTROL INTERFACE
CK
VCC
GND
C0-C7 A0-A3 R/W
CS
Figure 1. GC1012A Block Diagram
Each of these functions are described below.
SYNCS OUT
(SO,OS,INT,OFLOW)
1.3 CONTROL INTERFACE
The control interface performs four major functions: It allows an external processor to configure the
chip, it allows an external processor to capture and read output samples from the chip, it allows an external
processor to perform diagnostics, and it generates internal synchronization strobes.
The chip is configured by writing control information into 8 bit control registers within the chip. The
contents of these control registers and how to use them are described in Section 3. The registers are written
to or read from using the C[0:7], A[0:3], R/W, and CS pins. Each control register has been assigned a
unique address within the chip. An external processor (a microprocessor, computer, or DSP chip) can write
into a register by setting A[0:3] to the desired register address, setting the R/W pin low, setting D[0:7] to
the desired value and then pulsing CS low.
To read from a control register the processor must set A[0:3] to the desired address, set R/W high,
and then set CS low. The chip will then drive C[0:7] with the contents of the selected register. After the
processor has read the value from C[0:7] it should set CS high. The C[0:7] pins are turned off (high
impedance) whenever CS is high or R/W is low. The chip will only drive these pins when CS is low and R/W
is high.
GRAYCHIP,INC.
-2-
FEBRUARY 18, 1998
This document contains information which may be changed at any time without notice