User Manual

34 DS671F2
CS4385
4.14.3 SPI Mode
In SPI Mode, data is clocked into the serial control data line, CDIN, by the serial control port clock, CCLK
(see Figure 27 for the clock to da ta relationship). There is n o AD0 pin. Pin CS
is the chip select signal and
is used to control SPI writes to the control port. When the device detects a high to low transition on the
AD0/CS
pin after power-up, SPI Mode will be selected. All signals are inputs and data is clocked in on the
rising edge of CCLK.
4.14.3.1 SPI Write
To write to the device, follow the procedure below while adhering to the control port Switching Specifica-
tions in Section 1.
1. Bring CS
low.
2. The address byte on the CDIN pin must then be 00110000.
3. Write to the memory address pointer, MAP. This byte points to the register to be written.
4. Write the desired data to the register pointed to by the MAP.
5. If the INCR bit (see Sectio n 4.14.1 ) is set to 1, repeat the previous step until all the desired registers
are written, then bring CS
high.
6. I f the INC R bit is set to 0 and further SPI writes to other registers are desired, it is necessary to bring
CS
high, and follow the procedure detailed from step 1. If no further writes to other registers are de-
sired, bring CS
high.
4.15 Memory Address Pointer (MAP)
4.15.1 INCR (Auto Map Increment Enable)
Default = ‘0’
0 - Disabled
1 - Enabled
4.15.2 MAP4-0 (Memory Address Pointer)
Default = ‘00000’
76543210
INCR Reserved Reserved MAP4 MAP3 MAP2 MAP1 MAP0
00000000
MAP
MSB
LSB
DATA
byte 1
byte n
R/W
MAP = M emory Address Pointer
ADDRESS
CHIP
CDIN
CCLK
CS
0011000
Figure 27. Control Port Timing, SPI Mode