Datasheet
LTC6946
18
6946fa
OPERATION
Multiple Byte Transfers
More efficient data transfer of multiple bytes is accom-
plished by using the LTC6946’s register address auto-
increment feature as shown in Figure 12. The serial port
master sends the destination register address in the first
byte and its data in the second byte as before, but continues
sending bytes destined for subsequent registers. Byte 1’s
address is Addr0+1, Byte 2’s address is Addr0+2, and so
on. If the resister address pointer attempts to increment
past 11 (h0B), it is automatically reset to 0.
An example of an auto-increment read from the part is
shown in Figure 13. The first byte of the burst sent from
the serial bus master on SDI contains the destination reg-
ister address (Addr0) and an LSB of “1” indicating a read.
Once the LTC6946 detects a read burst, it takes SDO out
of the Hi-Z condition and sends data bytes sequentially,
A6 A5 A4 A3 A2
7-BIT REGISTER ADDRESS
Hi-Z
MASTER–CS
MASTER–SCLK
MASTER–SDI
LTC6946–SD0
A1 A0 0 D7 D6 D5 D4 D3 D2 D1 D0
8 BITS OF DATA
0 = WRITE
6946 F09
16 CLOCKS
Addr0 + Wr
Hi-Z
MASTER–CS
MASTER–SDI
LTC6946–SDO
Byte 0
Addr1 + Wr Byte 1
6946 F11
Addr0 + Wr
Hi-Z
MASTER–CS
MASTER–SDI
LTC6946–SDO
Byte 0 Byte 1 Byte 2
6946 F12
Figure 9. Serial Port Write Sequence
Figure 10. Serial Port Read Sequence
Figure 11. Serial Port Single Byte Write
Figure 12. Serial Port Auto-Increment Write
A6 A5 A4 A3 A2
7-BIT REGISTER ADDRESS
Hi-Z
Hi-Z
A1 A0 1
D7X D6 D5 D4 D3 D2 D1 D0 DX
8 BITS OF DATA
1 = READ
6946 F10
MASTER–CS
MASTER–SCLK
MASTER–SDI
LTC6946–SDO
16 CLOCKS