When i use the AD7732, the part always work under "no data read" status as figure 21 shows. And i wonder what is the mean for this status, and how to work under continuous read mode.
Hi Huang Peng,
Apologies for the delay.
Figure 21 of the datasheet shows the serial interface of AD7732 in continuous conversion mode when the data is available on the data register but is not read by the user. This means that when a conversion is complete as indicated by the /RDY going low, the user did not write 48h to the communication register to tell the device that the next operation is a read to the data register.
To use AD7732 in continuous read mode, you need to write 38h to communication register to tell the device that the next operation is a write to the mode register. You need to configured the device to run on continuous conversion mode and at the same time, set the Cont RD bit, you can do this by writing 24h to the mode register. When the Cont RD bit is set, the first write of 48h to the communications register will then start the continuous read mode. The status bits together with the data will be directly available on the DOUT pin after the /RDY goes low indicating that a conversion is complete.
The AD7732 will stay in continuous read mode as long as the DIN pin is low while the /CS pin is low; therefore, write 0 to the AD7732 while reading in continuous read mode. To completely stop the continuous read mode, write to the mode register to clear the Cont RD bit.
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