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AD7796/AD7797 Rev. A | Page 19 of 24 Continuous Read Mode Rather than write to the communication register each time a conversion is complete to access the data, the AD7796/AD7797 can be configured to automatically place the conversions on the DOUT/RDY line. By writing 01011100 to the communication register, the user need only apply the appropriate number of SCLK cycles to the ADC. The 16-/24-bit word is automatically placed on the DOUT/RDY line when a conversion is complete. The ADC should be configured for continuous conversion mode. When DOUT/RDY goes low to indicate the end of a conversion, sufficient SCLK cycles must be applied to the ADC. The data conversion is placed on the DOUT/RDY line. When the conver- sion 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 AD7796/AD7797 to read the word, the serial output register is reset when the next conversion is complete. The new conversion is placed in the output serial register. To exit continuous read mode, the instruction 01011000 must be written to the communication register while the DOUT/RDY pin is low. While in continuous read mode, the ADC monitors activity on the DIN line to receive the instruction to exit the continuous read mode. Additionally, a reset occurs if 32 consecutive 1s are seen on DIN. Therefore, DIN should be held low in continuous read mode until an instruction is written to the device. DIN SCLK DOUT/RDY CS 0x5C DATA DATA DATA Figure 16. Continuous Read |
