AD7699

Question

Hello, 
 I plan to use the AD7699 and I need to clarify how the configuration register initialization work after power-up. 
 The datasheet states: 
 "Note that at power-up, the CFG register is undefined and two dummy conversions are required to update the register" on page 24. 
 and 
 "the first 14 SCK rising edges update the CFG" on page 27. 
 So if I send the sequence "Conversion pulse + an SPI frame with only 14 SCK periods" twice. 
 Is the configuration register updated ? 
 Is the configuration register updated on the 14th SCK rising edge ? If not, what is the internal event updating CFG reg ? 
 I plan to use the ADC in the mode Read/write after convert with a busy indicator. 
 Thanks for your help, 
 Regards, 
 St&eacute;phane

NathanT · Accepted Answer

Hello breysse , 
 Thank you for your patience. Based on this thread, I think you understood its datasheet correctly. By doing a dummy conversion for two times then writing to the next conversion will have a valid data. 
 But in your last reply, you do not need to send it twice if you will write it after the dummy conversion since they are already a valid data. The data will be available after 2 cycles. (ie. If CFG(n) is written during the conversion(n) , data(n+1) will be available during the conversion(n+2)). 
 
 Thanks and regards, Jo)

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AD7699