English
Language : 

LMH0031 Datasheet, PDF (12/31 Pages) National Semiconductor (TI) – SMPTE 292M/259M Digital Video Deserializer Descrambler with Video and Ancillary Data FIFOs
Device Operation (Continued)
ANCILLARY/CONTROL DATA PATH
The 10-bit ancillary and Control Data Port AD[9:0] serves
two functions in the LMH0031. Ancillary Data from the An-
cillary Data FIFO is output from this port after its recovery
from the video data stream. The utilization and flow of Ancil-
lary Data from the device is managed by a system of control
bits, masks and IDs stored in the control data registers. This
port also provides read/write access to contents of the con-
figuration and control registers. The signals RD/WR, ANC/
CTRL and ACLK control data flow through the port.
CONTROL DATA FUNCTIONS
Control data is input to and output from the LMH0031 using
the lower-order 8 bits AD[7:0] of the ancillary/Control Data
Port. This control data initializes, monitors and controls op-
eration of the LMH0031. The upper two bits AD[9:8] of the
port function as handshaking signals with the device access-
ing the port. When either a control register read or write
address is being written to the port, AD[9:8] must be driven
as 00b (0XXh, where XX are AD[7:0]). When control data is
being written to the port, AD[9:8] must be driven as 11b
(3XXh, where XX are AD[7:0]). When control data is being
read from the port, the LMH0031 will output AD[9:8] as 10b
(2XXh, where XX are output data AD[7:0]) and may be
ignored by the monitoring system.
Note: After either a manual or power-on reset, ACLK must be
toggled three (3) times to complete initiallization of the An-
cillary and Control Data Port.
The sequence of clock and control signals for reading control
data from the ancillary/control data port is shown in Figure 2.
Control data read mode is invoked by making the ANC/
CTRL input low and the RD/WR input high. The 8-bit ad-
dress of the control register set to be accessed is input to the
port on bits AD[7:0]. To identify the data as an address,
AD[9:8] must be driven as 00b. The complete address word
will be 0XXh, where 0 is AD[9:8] and XX are AD[7:0]. The
address is captured on the rising edge of ACLK. When
control data is being read from the port, the LMH0031 will
output AD[9:8] as 10b (2XXh, where XX are output data
AD[7:0]) and may be ignored by the monitoring system. Data
being output from the selected register is driven by the port
immediately following the rising edge of ACLK or when the
address signal is removed. For optimum system timing, the
signals driving the address to the port should be removed
immediately after the address is clocked into the port and
before or simultaneously with the falling edge of ACLK at the
end of that address cycle. Output data remains stable until
the next rising edge of ACLK and may be written into external
devices at any time after the removal of the address signal.
This second clock resets the port from drive to receive and
readies the port for another access cycle.
Example: Read the Full-field Flags via the AD port.
1. Set ANC/CTRL to a logic-low.
2. Set RD/WR to a logic-high.
3. Present 001h to AD[9:0] as the register address.
4. Toggle ACLK.
5. Release the bus driving the AD port.
6. Read the data present on the AD port. The Full-field
Flags are bits AD[4:0].
7. Toggle ACLK to release the AD port.
Figure 3 shows the sequence of clock and control signals for
writing control data to the ancillary/control data port. The
control data write mode is similar to the read mode. Con-
trol data write mode is invoked by making the ANC/CTRL
input low and the RD/WR input low. The 8-bit address of the
control register set to be accessed is input to the port on bits
AD[7:0]. When a control register write address is being
written to the port, AD[9:8] must be driven as 00b (0XXh,
where XX are AD[7:0]). The address is captured on the rising
edge of ACLK. The address data is removed on the falling
edge of ACLK. Next, the control data is presented to the port
bits AD[7:0] and written into the selected register on the next
rising edge of ACLK. When control data is being written to the
port, AD[9:8] must be driven as 11b (3XXh, where XX are
AD[7:0]). Control data written into the registers may be read
out non-destructively in most cases.
Example: Setup (without enabling) the TPG Mode via the
AD port using the 1125 line, 30 frame, 74.25MHz, interlaced
component (SMPTE 274M) colour bars as test pattern. The
TPG may be enabled after setup using the Multi-function I/O
port or by the control registers.
1. Set ANC/CTRL to a logic-low.
2. Set RD/WR to a logic-low.
3. Present 00Dh to AD[9:0] as the Test 0 register address.
4. Toggle ACLK.
5. Present 327h to AD[9:0] as the register data.
6. Toggle ACLK.
www.national.com
12