BT848 ETC, BT848 Datasheet - Page 86

• Manufacturer Part Number: BT848
• Description: Single-Chip Video Capture for PCI
• Manufacturer: ETC

E
I
76
2
C Interface
LECTRICAL
I
NTERFACES
data (checking for a receiver acknowledge after each byte), and a STOP signal. The
write data is supplied from a 24-bit register with bytes I2CDB0, I2CDB1, and
I2CDB2. This 24-bit register is shifted left to provide data serially, with the MSB
as the first bit. An I
logical low. The system driver can select to write 2 or 3 bytes of data by selecting
the appropriate value for I2CW3B bit.
(checking for a receiver acknowledge), reading 1 data byte from the slave, sending
the master NACK, and sending the STOP signal. The data read is shifted into the
I2CDB2 register. An I
a logical one (Figure 36).
the PCI bus to the host controller. The status bit RACK will indicate whether the
operation completed successfully with the correct number of slave acknowledges.
driver can disable the I
SCL and SDA pins. This is useful in applications where the I
eral purpose I/O or if a special type of I
needs to be implemented.
Figure 36. I
Guide,” reprinted by Brooktree.
D
D
An I
An I
When the read or write operation is completed, Bt848 sends an interrupt over
In the case where direct control of the I
For detailed information on the I
S
S
ATA
ATA
2
W
R
2
CHIP ADDR
CHIP ADDR
C write transaction consists of sending a START signal, 2 or 3 bytes of
C read transaction consists of sending a START signal, 1 byte of data
EAD
RITE
2
C Typical Protocol Diagram
2
C write occurs when the R/W bit in the I2CDB0[0] is set to a
A
A
L848A_A
2
C read occurs when the R/W bit in the I2CDB0[0] is set to
2
DATA
C hardware control and can take software control of the
SUB
8
-
BITS
ADDR
NA
P
A
2
C bus, refer to “The I
DATA
2
2
C bus lines is desired, the Bt848 device
C operation (such as multi-mastering)
A
Single-Chip Video Capture for PCI
P
S
P
A
NA
2
C bus is used for gen-
F
F
=
=
=
=
Bt848/848A/849A
ROM
ROM
2
START
STOP
ACKNOWLEDGE
NON ACKNOWLEDGE
C-Bus Reference
B
S
T
LAVE TO
848
Brooktree
TO
B
S
T
LAVE
848
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