Datasheet

AD7280A
Rev. 0 | Page 40 of 48
Example 3: Convert and Read All Parts, All Voltages,
and Three Auxiliary ADC Inputs per Part
In this example, it is assumed that all AD7280As in the daisy
chain have been initialized to their correct device addresses.
1.
Write Register Address 0x00 to the read register on all
parts. A device address of 0x00 is used when computing
the CRC for commands to write to all parts. The 32-bit
write command is 0x038011CA (see Table 2 5, Write 1).
Note that 0x00 is the default value of the read register on
power-up and after a software reset; therefore, this write
operation may not be necessary.
2.
Set Bit D15 and Bit D13 of the control register to 0 on all
parts. Set Bit D14 and Bit D12 of the control register to 1
on all parts. The 32-bit write command is 0x01AA1062
(see Table 25, Write 2).
3.
Program the
CNVST
control register to 0x02 on all parts
to allow conversions to be initiated using the
CNVST
pin.
The 32-bit write command is 0x03A0546A (see ,
Write 3).
Table 25
4.
Initiate conversions through the falling edge of
CNVST
.
5.
Allow sufficient time for all conversions to be completed
plus t
WA I T
. Following the completion of all conversions,
apply a
CS
low pulse that frames 32 SCLKs for each conver-
sion result to be read back. The 32-bit write command is
0xF800030A, as described in the section
(see , Write 4).
Serial Interface
Table 25
Table 25. Example 3: Converting and Reading All Voltages and Three Auxiliary ADC Inputs from All AD7280A Devices
Write Command Device Address Register Address Data Write All D11 8-Bit CRC D2 to D0
32-Bit Write
Command
Write 1 00000 011100 00000000 1 0 00111001 010 0x038011CA
Write 2 00000 001101 01010000 1 0 00001100 010 0x01AA1062
Write 3 00000 011101 00000010 1 0 10000101 010 0x03A0546A
Write 4 11111 000000 00000000 0 0 01100001 010 0xF800030A