Datasheet

Data Sheet AD7176-2
Rev. A | Page 35 of 68
CONTINUOUS READ MODE
In continuous read mode, it is not required to write to the
communications register before reading ADC data; just apply
the required number of SCLKs after DOUT/
RDY
goes low to
indicate the end of a conversion. When the conversion is read,
DOUT/
RDY
returns high until the next conversion is available.
In this mode, the data can be read only once. The user must also
ensure that the data-word is read before the next conversion is
complete. If the user has not read the conversion before the
completion of the next conversion or if insufficient serial clocks
are applied to the
AD7176-2 to read the word, the serial output
register is reset when the next conversion is complete, and the
new conversion is placed in the output serial register. The ADC
must be configured for continuous conversion mode to use
continuous read mode.
To enable continuous read mode, set the CONTREAD bit in the
interface mode register. When this bit is set, the only serial interface
operations possible are reads from the data register. To exit con-
tinuous read mode, issue a dummy read of the ADC data register
command (0x44) while
RDY
is low. Alternatively, apply a software
reset, that is, 64 SCLKs with
CS
= 0 and DIN = 1. This resets the
ADC and all register contents. These are the only commands
that the interface recognizes after it is placed in continuous read
mode. DIN should be held low in continuous read mode until
an instruction is to be written to the device.
If multiple ADC channels are enabled, each channel is output
in turn, with the status bits being appended to the data if
DATA_STAT is set in the interface mode register. The status
register indicates the channel to which the conversion corresponds.
Figure 48. Continuous Read Mode
DIN
SCLK
DOUT/RDY
CS
0x02
DATA
DATA DATA
0x0800
1
1037-072