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In a test to see if I could route a 64 channel analog mux into a SAR I picked up on
an error associate with mux. It reported, as shown, only 5 address bits, but errored
when I gave it a 5 bit buss. Whn I gave it 6 bit buss it stopped complaing, but you can
see in symbol its still reporting only 5 bits needed.
Regards, Dana.
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Dana,
a 64 input mux = 2^6. Hence 6-bits of the counter is needed not 5.
"Engineering is an Art. The Art of Compromise."
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Yes, but tool is showing buss width at mux is only 5 bits, thats the error, the label
the tool shows. See circled label on the screenshot I posted.
Regards, Dana.
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Dana,
You are correct. It is a limitation of the AmuxHW component.
I imported the AMuxHW component into a project.
I opened the "AMuxHw_v1_50.cysym" file.
I select the "2" highlighted above.
The field came up:
`=($Mode == MuxMode)?(($Channels <= 2)? 1 : (($Channels <= 4)? 2:(($Channels <=8)?3:(($Channels <= 16)?4:5)))):($Channels)`
Based on the above equation, any number of Channels > 16 is treated as 2^5. There "5" is the largest "n" factor in 2^n.
This might only be a user feedback/visual issue. The actual feeding of a 6-bit bus (2^6) on a 64-bit mux might still work fine.
Someone would have to code review the ".v" (Verilog) file to determine if there would be a problem.
Update
I've modified the AMuxHW_v1_50 to AMuxHW_v1_51 where the bus width is increased to now support upto 128 Amux inputs (@ 7-bit bus width).
Just unarc the zip file attached into your project directory. It should show up on the Component Catalog.
"Engineering is an Art. The Art of Compromise."
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Hi,
It would be nice, if you can tell us which device and component you are using.
This time, I assumed a PSoC 4 and the component is Analog Hardware Mux.
At first I tried a 2-input Amux and it seems to be OK.
Then I tried a 16-input Amux and it seems to be OK.
Then I tried a 32-input Amux and it seems to be OK.
So far, so good 😉
Then I tried a 36-input Amux, this should require 6-bit for selector bus.
But it still shows 5! This could be a bug at this point.
Then I tried 64-input, which also should require 6-bit selector bus.
And I think that this is your case, too.
Then I went 128-input, which should require 7-bit selector bus.
Finally the maximum number of inputs, which is 256,
and the selector bus should be 8-bit
So what I observed is that the bit-width of the selector bus in the Analog Hardware Mux
with more than 32-input is incorrect.
I would call it a bug, if I may.
I hope that Infineon (Cypress) will fix this soon 😉
moto
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Hello,
We have forwarded your query to our internal team, who will evaluate your query.
We will provide a response as soon as we get an update from our internal team.
Thank you for your patience.
Thanks and Regards,
P Yugandhar