Read cycle – Rainbow Electronics MAX7470 User Manual
Page 13
MAX7469/MAX7470
HDTV Continuously Variable
Anti-Aliasing Filters
______________________________________________________________________________________
13
write sequence must be repeated. Figures 6 and 7
show examples of write sequences.
Read Cycle
In read mode (R/W = 1), the MAX7469/MAX7470 write
the contents of the control/status or frequency registers
to the bus. When the command byte indicates a read
operation of either the control/status or the frequency
register, the serial interface expects an Sr condition to
follow the command byte. After sending an Sr, the mas-
ter sends the MAX7469/MAX7470 slave address byte
followed by a R/W bit (set to 1 to indicate a read). The
slave device (MAX7469/MAX7470) generates an ACK
for the second address word and immediately after the
ACK clock pulse, the direction of data flow reverses.
The slave (MAX7469/MAX7470) then transmits 1 byte of
data containing the value of the register that was
SDA
SCL
1
0
0
1
0
A1
A0
R/W
C7
C6
C5
C4
C3
C2
C1
C0
ACK
ACK
OUT
IN
OUT
IN TO MAX7469/MAX7470
SDA (CONT)
SDA
DIRECTION
SDA
DIRECTION
SCL (CONT)
F7
F6
F5
F4
F3
F2
F1
ACK
OUT
F0
IN
IN
START
STOP
0
0
0
1
0
0
1
0
COMMAND BYTE C7–C0 IS 0010010.
SDA
SDA
DIRECTION
SCL
1
0
0
1
0
A1
A0
R/W
C7
C6
C5
C0
ACK
ACK
OUT
IN
OUT
IN TO MAX7469/MAX7470
IN
START
STOP
0
0
0
0
0
0
0
0
C4
C3
C2
C1
THE COMMAND BYTE IS FOR POWER-DOWN.
Figure 6. Write Sequence to Update the Frequency Register
Figure 7. Write Sequence for a Command Byte