Datasheet

ADS8634
ADS8638
SBAS541A –MAY 2011– REVISED AUGUST 2011 www.ti.com
DIN DATA FORMAT (SPI COMMAND WORD)
Device registers can be written to and read from. There must be a minimum of 16 SCLKs after the CS falling
edge for any read or write operation. The device receives the command (as shown in Table 9 and Table 10)
through DIN where the first seven bits (bits[15:9]) represent the register address and the eighth bit (bit 8) is the
read/write instruction. For a write cycle, the next eight bits (bits[7:0]) in the DIN are the desired data for the
addressed register (Table 9). For a read cycle, the next eight bits (bits[7:0]) in the DIN are don’t care. DOUT
outputs the 8-bit data from the addressed register (Table 10) during these eight clocks, corresponding to
bits[7:0].
Table 9. Write Cycle Command Word
RD/
REGISTER ADDRESS DATA
WR
PIN Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
ADDR ADDR ADDR ADDR ADDR ADDR ADDR
DIN R/W DIN7 DIN6 DIN5 DIN4 DIN3 DIN2 DIN1 DIN0
6 5 4 3 2 1 0
Table 10. Read Cycle Command Word
RD/
REGISTER ADDRESS DATA
WR
PIN Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
ADDR ADDR ADDR ADDR ADDR ADDR ADDR
DIN R/W X X X X X X X X
6 5 4 3 2 1 0
DOUT DOUT DOUT DOUT DOUT DOUT DOUT DOUT
DOUT X X X X X X X X
7 6 5 4 3 2 1 0
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