comunication issue on ADIS 16470

I have recently purchased a breakout board of the ADIS16470 (ADIS16470/PCBZ).
I tested it with a discovery board (through the SPI port) and I had an issue. I attach an image of the oscilloscope used on the test.
- In yellow (1st channel) -> Clock
- In Blue (2nd channel) -> DIN (MISO)
- In purple (3rd channel) -> DOUT (MOSI)
The circles highlighted the SPI transaction.
In order to get a correct response, I had to send 32-bit clock pulse instead of a 16-bit one (I have to wait 32 instead of 16).
I have asked for the PROD_ID (0x72) (1_petition image). As in the datasheet Figure 28 example.

On the other hand, I have also asked for the PROD_ID (0x72) 3 times (3_petition image) consecutively.
In this case, the first response takes 8 clock cycles (this is not ok, isn't it?), an then the other ones arrive "together", without any gap.

1_petition   3_petitions

Am I doing anything wrong? Is this supossed to happen?

Parents Reply
  • 0
    •  Analog Employees 
    on Nov 13, 2018 12:33 AM over 1 year ago in reply to miguekf18

    Thank you! I understand that this can be frustrating, but I can assure you that the protocol in the datasheet represents how we test these devices in practice and how many others are using them. The only other thing that I would wonder about is the chip select line.  It wasn't shown in the scope plots so I wasn't able to review its timing.  I will be travelling the rest of the week, so apologies if my future replies are delayed.