effecting one bit in a bus passing the rest through, with schematic


Chris_C

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At the moment I'm learning about schematic capture, which if nothing else is making me not do everything in one horrible giant cludge of a vhdl module :o)

 

I wanted to invert just one bit of a bus, yes I know I could very quickly write a tiny vhdl module and make a schematic symbol from it but bare with me that's not the point

 

My issue is with bus tap - again! - never have I seen something so badly and unituitvly implemented and in 30+ years of messing with electronics and programming that really says something

 

Now I have fairly well got the hang of getting a tap into or out of a bus (holy cow I might have to make a YouTube about it) , but what now seems problematic is a tap from one part of a bus to part of another bus without some intermediary.

 

I ended up making a symbol from a separate schematic with two busses 7 buffers and 1inverter.

 

Is there a better schematic method of effecting just 1 bit in a bus?

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Hey Chris,

 

I agree with you on the bus stuff in the schematic editor, I've actually been bending over backwards with DesignLab to avoid using buses... I'm afraid it will cause too much confusion, I have struggled with it too. 

 

I am having a bit of trouble understanding what it is you are trying to do, can you maybe take a screenshot? I think the answer though is that you need some kind of intermediary... In VHDL its trivial to connect one bit of a bus to anything else, with just a single line of code. But in the schematic editor that doesn't work, you need something like an obuf or ibuf, otherwise the tool seems to get confused or something. That took me a long time to figure out, mostly because I would just make a VHDL module to do what I wanted though. :)

 

Jack.

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