AnsweredAssumed Answered

AD7190 serial communication issues

Question asked by Marco00 on Jun 16, 2011
Latest reply on Aug 13, 2013 by ChrisD.Rama

Dear all,

I'm collecting some problems with the AD7190 serial communication.

I use the 3-wire serial interface (SCLK, DIN, DOUT) with CS tied low. SCLK is 10 kHz and the sequence of events is described below:

1. I power up the board

2. I set both SCLK and DIN

3. I send a train of 40 SCLK pulses with DIN setted to perform a reset (I also tried to increment the number of SCLK pulses up to 48).

 

After this operation I cannot always find the same signal state, I have two different conditions:

-DOUT/RDY is a low signal with high pulses of 100 microseconds spaced by 20ms. Each time I see the high pulse a new data is available. Is it correct? I can leave the system in this condition for a lot of time (some minutes) and signal modifications doesn't occur.

-DOUT/RDY is as I described before only for 4 "conversions" (4 high pulses); after that I always read a low DOUT/RDY signal. Also in this condition I can leave the system for minutes without signal modifications.

 

Which is the correct signal timing diagram after the reset condition in 3-wire serial communication interface? Am I doing mistakes?

 

I would like to use the AD7190 in continuos conversion mode (the default after power up / reset) so after the reset I send 8 SCLK pulses and h58 on DIN (rising edge synchronuos); than 2ms with DIN and SCLK tied high and after that a train of 24 SCLK pulses to read the data register. May be for reset mismatch but I cannot always see the same result on DOUT, also writing for example h50 and trying to read the configuration register.

In every condition, I check the DOUT/RDY pin to be low before starting to write.

 

The board wire connections make available to the AD7190 this signal levels:

AVdd=5V

DVdd=5V

AGND=DGND=0V

REFIN1(+)=2,5V

REFIN1(-)=0V

CS=0V

AIN1 short circuited with AIN2 (with this condition I should have 0x800000 on Data Register -> never had)

 

SCLK/DIN high=5V

SCLK/DIN low=0V

 

 

Thank you in advance for your cooperation,

 

best regards

Marco

Outcomes