LM1237_04 datasheet(20/42 Pages) NSC

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Microcontroller Interface (Continued)

READ SEQUENCE

Read sequences are comprised of two I

2C compatible trans-

fer sequences: The first is a write sequence that only trans-

fers the two byte address to be accessed. The second is a

read sequence that starts at the address transferred in the

previous address only write access and increments to the

next address upon every data byte read. This is shown in

Figure 20. The write sequence consists of the Start Pulse,

the Slave Device Address, the Read/Write bit (a zero, indi-

cating a write) and the Acknowledge bit; the next byte is the

least significant byte of the address to be accessed, followed

by its Acknowledge bit. This is then followed by a byte

containing the most significant address byte, followed by its

Acknowledge bit. Then a Stop bit indicates the end of the

address only write access. Next the read data access will be

performed beginning with the Start Pulse, the Slave Device

Address, the Read/Write bit ( a one, indicating a read) and

the Acknowledge bit. The next 8 bits will be the read data

driven out by the LM1237 preamp associated with the ad-

dress indicated by the two address bytes. Subsequent read

data bytes will correspond to the next increment address

locations. Data should only be read from the LM1237 when

both OSD windows are disabled.

20023426

FIGURE 19. I

2C Compatible Write Sequence

20023427

FIGURE 20. I

2C Compatible Read Sequence

LM1237 Datasheet(PDF) 20 Page - National Semiconductor (TI)