ad7853lan Analog Devices, Inc., ad7853lan Datasheet - Page 28

• Manufacturer Part Number: ad7853lan
• Description: 3 V To 5 V Single Supply, 200 Ksps 12-bit Sampling Adcs
• Manufacturer: Analog Devices, Inc.

AD7853/AD7853L
Writing to the AD7853/AD7853L
For accessing the on-chip registers it is necessary to write to the
part. To enable Serial Interface Mode 1, the user must also
write to the part. Figure 41 through 43 outline flowcharts of
how to configure the AD7853/AD7853L for each of the differ-
ent serial interface modes. The continuous loops on all diagrams
indicate the sequence for more than one conversion. The options
of using a hardware (pulsing the CONVST pin) or software
(setting the CONVST bit to 1) conversion start, and reading/
writing during or after conversion are shown in Figures 41 and
42. If the CONVST pin is never used then it should be tied to
DV
SCLK, READ PREVIOUS CONVERSION
DD
AFTER CONVST RISING EDGE
WAIT APPROXIMATLY 200ns
AND WRITE ALL 0s ON DIN PIN
APPLY SYNC (IF REQUIRED),
permanently. Where reference is made to the BUSY bit
RESULT ON DOUT PIN,
Figure 41. Flowchart for Setting Up, Reading and Writing in Interface Modes 2 and 3
CURRENT CONVERSION RESULT ON DOUT PIN,
APPLY SYNC (IF REQUIRED), SCLK, READ
WAIT FOR AUTOMATIC CALIBRATION
POWER-ON, APPLY CLKIN SIGNAL,
LOW OR WAIT FOR BUSY BIT = 0
WAIT FOR BUSY SIGNAL TO GO
YES
AND WRITE ALL 0s ON DIN PIN
PULSE CONVST PIN
CONVERSION
CONVERSION
INTERFACE
SOFTWARE
TRANSFER
INITIATE
DURING
SERIAL
START
MODE
DATA
IN
?
?
?
NO
NO
2, 3
YES
APPLY SYNC (IF REQUIRED), SCLK, WRITE TO CONTROL
REGISTER SETTING CONVST BIT TO 1, READ CURRENT
–28–
WAIT FOR BUSY SIGNAL TO GO LOW
equal to a Logic 0, to indicate the end of conversion, the user in
this case would poll the BUSY bit in the status register.
Interface Modes 2 and 3 Configuration
Figure 41 shows the flowchart for configuring the part in Inter-
face Modes 2 and 3. For these interface modes, the read and
write operations take place simultaneously via the serial port.
Writing all 0s ensures that no valid data is written to any of the
registers. When using the software conversion start and transfer-
ring data during conversion, Note must be obeyed.
CONVERSION RESULT ON DOUT PIN
NOTE:
WHEN USING THE SOFTWARE CONVERSION START AND TRANSFERRING
DATA DURING CONVERSION THE USER MUST ENSURE THE CONTROL
REGISTER WRITE OPERATION EXTENDS BEYOND THE FALLING EDGE OF
BUSY. THE FALLING EDGE OF BUSY RESETS THE CONVST BIT TO 0 AND
ONLY AFTER THIS TIME CAN IT BE REPROGRAMMED TO 1 TO START THE
NEXT CONVERSION.
OR WAIT FOR BUSY BIT = 0
DATA DURING
CONVERSION
TRANSFER
NO
APPLY SYNC (IF REQUIRED), SCLK, WRITE TO CONTROL
REGISTER SETTING CONVST BIT TO 1, READ PREVIOUS
YES
CONVERSION RESULT ON DOUT PIN (SEE NOTE)
REV. B