Great, I look forward to it. Is the scaling (right shifts, I presume) the same on both channels? (Note that with those pins chosen, cog 0 would be the ideal for reading channel B, while cog 7 would be best for reading A.)
Oh, another question...does the cross-talk disappear when using the original 2-channel ADC object?
Great, I look forward to it. Is the scaling (right shifts, I presume) the same on both channels? (Note that with those pins chosen, cog 0 would be the ideal for reading channel B, while cog 7 would be best for reading A.)
Oh, another question...does the cross-talk disappear when using the original 2-channel ADC object?
Jonathan
The origional had a squarer interference your averaging seems to work.
In Phil's SW Radio code he does some work to align phsa and phsb because phsb was loaded later.
I don't think that should affect the Easy ADC though
mov phsb,_90deg ' the other to the quadrature offset.
add phsb,rb 'Then adjust the phase by 4xNCO freq
add phsb,rb ' to account for frqb being loaded
add phsb,rb ' four clocks later than frqa.
Ok I tried other pins. I think there is crosstalk, but it is in/near the stereo earphone jack that I normally use to connect the propeller to the outside world.
Perry:
Thank you again for this.
As soon as I can figure out Sample and hold, I intend to modify the Poor Mans DSO to sample faster, and then attempt to capture live VGA video to SRAM.
to show the ADC schematic and values. With that in mind I have added vMax and vMin values to the config file for the conversions to voltage display.
I have moved schematic's to the config file.
I am now working on a trigger mechanism. My present thoughts involve another cog that increments a hub variable when the trigger is activated. That way you could detect missed triggers.
We also need a time out on the trigger mechanism to prevent the whole app from hanging.
Cool. As for triggering, I have a couple of ideas floating around, but no time to try them out yet. There are some fairly simple ways to avoid locking the application as well, the easiest being to kill the cog and restart the ADC if you don't get a response in the desired time. I'm a bit busy right now, but should have some free time next week if you have any features you'd like me to add.
Comments
Oh, another question...does the cross-talk disappear when using the original 2-channel ADC object?
Jonathan
The origional had a squarer interference your averaging seems to work.
In Phil's SW Radio code he does some work to align phsa and phsb because phsb was loaded later.
I don't think that should affect the Easy ADC though
mov phsb,_90deg ' the other to the quadrature offset. add phsb,rb 'Then adjust the phase by 4xNCO freq add phsb,rb ' to account for frqb being loaded add phsb,rb ' four clocks later than frqa.Thanks, gotta make dinner now.
Thank you again for this.
As soon as I can figure out Sample and hold, I intend to modify the Poor Mans DSO to sample faster, and then attempt to capture live VGA video to SRAM.
davidsaunders:
If you really want high speed input, consider using a high speed successive approximation chip. read the data using the "sweet spot ina to hub transfers".
http://forums.parallax.com/showthread.php?130648-Sweet-spot-INA-to-HUB-Byte-Transfers-(6MB-s-or-48Mbit-s-1-COG-96MHz)
lonesock:
When I first saw your schematic I thought "great balanced inputs"!
not sure that changing gain externally is that useful, scaling and offset is enough for me.
I like rayman's http://www.pulsedpower.net/Applets/Electronics/SigmaDeltaADC/SigmaDeltab.html
to show the ADC schematic and values. With that in mind I have added vMax and vMin values to the config file for the conversions to voltage display.
I have moved schematic's to the config file.
I am now working on a trigger mechanism. My present thoughts involve another cog that increments a hub variable when the trigger is activated. That way you could detect missed triggers.
We also need a time out on the trigger mechanism to prevent the whole app from hanging.
Perry
Jonathan