Serial programming interface – Rainbow Electronics MAX19505 User Manual

Page 16

MAX19505

Dual-Channel, 8-Bit, 65Msps ADC

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Serial Programming Interface

A serial interface programs the MAX19505 control reg-
isters through the

CS, SDIN, and SCLK inputs. Serial

data is shifted into SDIN on the rising edge of SCLK
when

CS is low. The MAX19505 ignores the data pre-

sented at SDIN and SCLK when

CS is high. C

S must

transition high after each read/write operation. SDIN
also serves as the serial-data output for reading control
registers. The serial interface supports two-byte transfer
in a communication cycle. The first byte is a control
byte, containing the address and read/write instruction,
written to the MAX19505. The second byte is a data
byte and can be written to or read from the MAX19505.

Figure 6 shows a serial-interface communication
cycle. The first SDIN bit clocked in establishes the

communication cycle as either a write or read transac-
tion (0 for write operation and 1 for read operation). The
following 7 bits specify the address of the register to be
written or read. The final 8 SDIN bits are the register
data. All address and data bits are clocked in or out
MSB first. During a read operation, the MAX19505 serial
port drives read data (D7) into SDIN after the falling
edge of SCLK following the 8th rising edge of SCLK.
Since the minimum hold time on SDIN input is zero, the
master can stop driving SDIN any time after the 8th ris-
ing edge of SCLK. Subsequent data bits are driven into
SDIN on the falling edge of SCLK. Output data in a read
operation is latched on the rising edge of SCLK. Figure
7 shows the detailed serial-interface timing diagram.

R/W

0 = WRITE
1 = READ

SCLK

SDIN

ADDRESS

DATA

WRITE OR READ

CSS

CSH

SDD

SDS

SDH

SCLK

SDIN

WRITE

READ

Figure 6. Serial-Interface Communication Cycle

Figure 7. Serial-Interface Timing Diagram