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EVAL-AD2S1205

Category: Hardware
Product Number: AD251205

I'm trying to use the EVAL-AD2S1205SDZ evaluation board to acquire the position data from a synchro/resolver through the SPI communication. For angles between 180° and 360° I get to read the right data (2048 - 4095), However for all the angles between 0° and 180° the SPI frame is tied to GND so the 16 bits are zeros. I verified many times the datasheet and the SPI signals provided by our microcontroller are OK. We also tested on the parallel mode and it works fine but unfortunately, we are forced to use the SPI interface. Should we replace the integrated circuit from the evaluation board or there is any other solution?

Top Replies

  • Hi  ,

    We will look into this. I will contact the product owner and get back to you.

    Regards,

    JC

  • Hi Zakaria,

          This is weird. I initially thought that there could be issue in the input side connection. But you mentioned that no issue when reading with parallel mode. You can read 0 to 360. The issue only appears on SPI mode and only for 0 to 180. The only difference i can see in the SPI result is that 180 to 360 the MSB value is 1. But for angles lower than 180 is the MSB is zero. In your software is there a difference capturing information when angles between 0 to 180 and 180 to 360? Are the SCLK always present on all angles?

    Regards,

    Jonathan

  • Thanks for your answer  the results that I got:

    -From 0° to 180° (0 to 2048 expected) received position = 0. (frame stuck at 0V, parity + error bit included).

    -From 180° to 360° (2048 to 4095 expected) received position partially ok. (We receive data from 2048 to 2300, then block at 2300, then from 2700 to 3200, then from 3700 to 4000...).

    We can't understand why we can't get data from 0° to 180° via the SPI (+ erratic operation from 180° to 360°).
    The data received being ok via the incremental and parallel outputs, we exclude a problem with the sensor wiring or the excitation signal.

    Here is the test configuration :

    - Admotec_RO5032 sensor (datasheet attached)
    - Power supply to the evaluation board via the 12V, 5V (DVCC) and 5V (AVCC) inputs.
    - LK1 = A ; LK2 = A ; LK3 = C (RDVEL position) ; LK4 = A ; LK6 = B (serial mode) ; LK5 = not inserted (10 khz) ; LK7, LK8 = C (0,866 gain -> 4Vpp max inputs) ; LK501, LK701, LK702 = B (external alims).

    SPI Frames : 


    Regards,

  • Hi Zakaria,

       Thanks for all this information. You are using your own digital controller. With SPI you connect the digital signal directly to the device pinouts and not via the level shifters,right? Wherr is the supply of your controller come from? Do they have common digital ground with AD2S1205? Would you also be able to have plots on the sine and cosine signal for the 0 to 360. 

    Regards,

    Jonathan

  • Yes we are using our own digital controller. We have level shifters on our main board, so interface with the eval board is 5V. The supply of our controller come from an isolated power supply so we connected digital grounds between the two boards. We were able to have proper data from the parralel mode interface, so we excluded a measure chain issue (excitation, sensor). But if really necessary we can plot the cos and sin from 0 to 360.

  • Hi Zakaria,

            In the image, the data channel (green) look like there are data but the level is very low. Is my assumption correct? Is the data line connected to another component. For isolation purposes, would it be possible that data line will be disconnected to other component and just the oscilloscope connected to this data line?

    Regards,

    Jonathan

  • Hello, the SPI is beeing used only for the AD2S1205, there are no other components. What you see on the data channel seems to be noise from the clock signal.

    Our problem is that the AD2S1205 returns data only when the motor position is between 180° and 360°. However between 0° and 180° the data channel is permanently pulled to 0V. The signals provided by our microcontroller (SCLCK, SAMPLE, CS, RD, RDVEL) are exactly the same for 180°- 360° and 0° - 180°.

    We've already replaced the component and verified many times the datasheet but we still have the same results. When used in parallel mode, the component works fine.

    Could you tell us if there is any example project where this component was used in serial mode?

  • Hi  

            Just for a check. Would you be able to have scope shot on the pins NM, A  and B? If you can share your schematic it would be nice.

    Regards,

    Jonathan