TLFD600 Datasheet, PDF (9/37 Pages) Texas Instruments – ADSL CODEC WITH INTEGRATED LINE DRIVER AND RECEIVER

TLFD600
ADSL CODEC WITH INTEGRATED LINE DRIVER AND RECEIVER
SLAS280B – MAY 2000 – REVISED NOVEMBER 2000
primary transfer data mapping
The data bit mapping of a primary transfer is shown in Figure 3. D15 – D2 bits of the SDR data stream are DAC
data. D1 is unused. D0 is the secondary transfer request bit. When a 1 is written to D0, the host is requesting
a secondary data transfer.
In the SDX data stream, D15 – D2 contain the ADC conversion data. D1 and D0 can be configured to reflect the
values of GPIO0 and GPIO1, when they are configured as inputs. D1 and D0 will contain zeroes if they are not
configured to reflect their corresponding GPIO pin value, or if the GPIO pin is configured as an output. To
configure D1 and D0 to reflect the GPIO values, the proper bit in the control register needs to be set.
DAC Data
Secondary Transfer Request
SDR
D15 – D2
X
D0
A/D Data
GPIO1 and GPIO0 Status
SDX
D15 – D2
D1
D0
GPIO1 GPIO0
Figure 3. Primary Transfer Data Bit Mapping
secondary transfer data mapping
Secondary serial communication is used to configure the device. The data bit mapping for a secondary transfer
is shown in Figure 4. The D14 – D10 bits of the SDR data, from the host, are the address bits of the control
register involved in the transfer. Bits D7 – D0 contain the data to the register. D15 needs to be set to zero all the
time.
A control register read-back function is not supported. As a result, there is no secondary FSX or SDX.
D15
D9 D8 D7
D0
SDR (Write) ^{0 A4 A3 A2 A1 A0}
Register Address ^{Don’t Care}
Data to the Register
Figure 4. Secondary Transfer Data Bit Mapping
example data transfers
Figure 5 and 6 show the timing relationship for SCLK, FSX, SDX, FSR, and SDR in a primary or secondary
communication. The update rate for TX and RX are controlled by pin configuration and register programming.
The timing sequence for this operation is as follows:
1. FS is brought high and remains high for one SCLK period, then goes back low.
2. A 16-bit word is transmitted from the ADC (SDX) and a 16-bit word is received for DAC conversion (SDR).
Figure 5 through 14 show the timing relationship of the data transfers with and without secondary request.
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