Hello,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.
Am I doing anything wrong? Is this supossed to happen?
Thank you for your interest in this product and for posting this question! I suspect that the primary issue could be a violation of the read stall time. See Table 2 and Figure 4 in the ADIS16470 datasheet and let me know what you think.
Just to follow-up, the specification requires a 16-bit command to make the read request, followed by a second 16-bit cycle, to receive the data from the request. The timing of the second request needs to meet the stall and readrate requirements. In the second case, I suspect that you could be reading the data before it updates, but wouldn't notice, since its contents will not change anyway (reading same address). I would focus on meeting the protocol, per the datasheet, rather than exploring what the device might do, when you operate outside of the specified protocol. Hope that helps!
We began (meeting the specified protocol of course), by testing if the problem were one of those (both times), and we did not succeed neither.
I will try to post the oscilloscope images of those tests tomorrow.
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.
thank you very much. Yes, of course I understand, and I know that the protocol is for sure working. I did my question wrong, definitely. The appropiated question should be "what am I doing wrong?".