AD7851ARS datasheet(29/36 Pages) AD

29 / 36 page

–29–

REV. A

AD7851

Interface Mode 1 Configuration

Figure 42 shows the flowchart for configuring the part in Inter-

face Mode 1. This mode of operation can only be enabled by

writing to the control register and setting the 2/3 MODE bit.

Reading and writing cannot take place simultaneously in this

mode as the DIN pin is used for both reading and writing.

SERIAL

INTERFACE

MODE

POWER-ON, APPLY CLKIN SIGNAL,

WAIT 150ms FOR AUTOMATIC CALIBRATION

YES

WAIT FOR BUSY SIGNAL TO GO

LOW OR WAIT FOR BUSY BIT = 0

READ

DATA

DURING

CONVERSION

APPLY

SYNC (IF REQUIRED), SCLK, READ

CURRENT CONVERSION RESULT ON DIN PIN

INITIATE

CONVERSION

SOFTWARE

WAIT APPROXIMATLY 200ns

AFTER

CONVST RISING EDGE

OR AFTER END OF CONTROL

APPLY

SYNC (IF REQUIRED),

SCLK, READ PREVIOUS CONVERSION

RESULT ON DIN PIN

YES

APPLY

SYNC (IF REQUIRED),

SCLK, WRITE TO CONTROL REGISTER

SETTING THE TWO-WIRE MODE

AND CONVST BIT TO 1

START

APPLY

SYNC (IF REQUIRED),

SCLK, WRITE TO CONTROL REGISTER

SETTING THE TWO-WIRE MODE

PULSE

CONVST PIN

Figure 42. Flowchart for Setting Up, Reading, and Writing

in Interface Mode 1

Interface Modes 4 and 5 Configuration

Figure 43 shows the flowchart for configuring the AD7851 in

Interface Modes 4 and 5, the self-clocking modes. In this case it

is not recommended to use the software conversion start option.

The read and write operations always occur simultaneously and

during conversion.

POWER-ON, APPLY CLKIN SIGNAL,

WAIT 150ms FOR AUTOMATIC CALIBRATION

SYNC AUTOMATICALLY GOES

LOW AFTER

CONVST RISING EDGE

PULSE

CONVST PIN

SCLK AUTOMATICALLY ACTIVE, READ CURRENT

CONVERSION RESULT ON DOUT PIN, WRITE

TO CONTROL REGISTER ON DIN PIN

4, 5

START

SERIAL

INTERFACE

MODE

Figure 43. Flowchart for Setting Up, Reading, and Writing

in Interface Modes 4 and 5

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