Datasheet

AD7280A
Rev. 0 | Page 43 of 48
Example 7: Self-Test Conversion on All Parts
Example 7 shows a self-test conversion routine for all parts in a
daisy chain.
1.
To select the self-test conversion, set Bits[D15:D14] of the
control register to 1, and set Bits[D13:D12] of the control
register to 0 on all parts. The 32-bit write command is
0x01B81092 (see Table 29, Write 1).
2.
Set Bit D0 of the control register to 1 on all parts. This
setting enables the daisy-chain register read operation on
all parts. The 32-bit write command is 0x01C2B6E2 (see
Table 29, Write 2).
3.
The register address corresponding to the self-test
conversion should be written to the read register of all
parts (see Table 13 for register addresses). The 32-bit write
command is 0x038617CA (see Table 29, Write 3).
4.
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 4).
Table 29
5.
Initiate conversions through the falling edge of
CNVST
.
6.
Allow sufficient time for the self-test conversions to be
completed plus t
WA I T
.
7.
The
CNVST
control register should be programmed to
gate the
CNVST
signal on all parts. The 32-bit write
command is 0x03A0340A (see , Write 5). This
write prevents unintentional conversions from being
initiated by noise or glitches on the
Table 29
CNVST
pin. This write
also updates the on-chip output registers of all devices in
the daisy chain.
8.
Apply a
CS
low pulse that frames 32 SCLKs to read back
the desired voltage. This frame should simultaneously
write the 32-bit command 0xF800030A, as described in
the section (see , Write 6). Serial Interface Tabl e 29
Example 8: Software Reset on All Parts
Example 8 shows a software reset routine for all parts in a
daisy chain.
1.
Set Bit D7 of the control register to 1 on all parts to place
the AD7280A into software reset. The 32-bit write command
is 0x01D2B412 (see Table 30 , Write 1).
2.
Set Bit D7 of the control register to 0 on all parts to take the
AD7280A out of software reset. The 32-bit write command
is 0x01C2B6E2 (see Table 30 , Write 2).
Table 29. Example 7: Self-Test Conversion on 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 001101 11000000 1 0 00010010 010 0x01B81092
Write 2 00000 001110 00010101 1 0 11011100 010 0x01C2B6E2
Write 3 00000 011100 00110000 1 0 11111001 010 0x038617CA
Write 4 00000 011101 00000010 1 0 10000101 010 0x03A0546A
Write 5 00000 011101 00000001 1 0 10000001 010 0x03A0340A
Write 6 11111 000000 00000000 0 0 01100001 010 0xF800030A
Table 30. Example 8: Software Reset for 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 001110 10010101 1 0 10000010 010 0x01D2B412
Write 2 00000 001110 00010101 1 0 11011100 010 0x01C2B6E2