ZMOD ADC channel B output format

[su_21]

Hello friends,

I am working on Eclypse Z7 with ADC ZMOD1410, I have performed acquisition of the signals as per my requirement. I am using two ZMOD’s with four channels for acquisition of signals. However, I need clarity on output format of channel 2(or B) of each ZMOD’s, whether it is in 2’s complement form or gray code format.

When checked into the VHDL code of ZMOD low level controller 1410 IP, the ADC SPI command is x"001421" which is written for 2’s complement and followed by x"000502" means device index B and that can be verified with datasheet. But at the same time, in the comment it is mentioned that channel 2(or B) is having gray code as output format.

I applied same signal to both channel 1 (or A) and channel 2 (or B) of same ZMOD, if I consider the output format to be 2’complement for both channels, I expect nearly the same the data. However, this is not the case, channel 2 (or B) is having different values. Whatever constant DC voltage applied to channel 2(or B) is treated as zero level when plot the digitized data.

If anyone knows any information about the same, it’ll be very helpful.

Thanking you in advance.

[JColvin]

Hi @su_21,

I have reached out to another engineer for some feedback on this question.

Thank you,
JColvin

[Cristian.Fatu]

The output format is 2's complement. We apologize, there is a mistake in our comment.
Regarding the generated value, please verify the coupling. You shouldn't have AC coupling selected.
On the other hand I inform you that we are preparing a release of a new version of ZmodIP.
Thank you very much for your output.

[su_21]

Hello @Cristian.Fatu,

Thank you very much for the reply and answer.

However I have made correct AC coupling settings for both channel. After more digging into the IP, I found that there is small mistake for channel 2 coupling Handling. So, basically the AC_DC coupling for channel 1 and channel 2 are inverted. You can find the same in the attached screenshot of RTL for ZMOD 1410 LLC.(Highlighted Lines).

[Cristian.Fatu]

Hello,

You are right about the problems in the Zomod IP. Although not fully released, I am sending you the location of the new Zmod IP, where these problems are solved: https://github.com/Digilent/vivado-library/tree/feature/lowlevel_zmod_ips_v2/ip/Zmods

Please be aware that this is a beta version.

Good luck.