feedback loop

Software questions and issues with the FV-1

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tjm215
Posts: 18
Joined: Sun Dec 22, 2013 8:07 am

feedback loop

Post by tjm215 »

trying to make a feedback loop - connect the input to the output. It can be done with hardware I know but I would like to do it with code. any idea? looking to have one of the pots control the level of feedback.

thanks!
frank
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Joined: Wed Oct 19, 2005 12:26 pm
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Post by frank »

Just write the final output to a register as well as the DAC then in the code read the register where you want the feedback.
Frank Thomson
Experimental Noize
tjm215
Posts: 18
Joined: Sun Dec 22, 2013 8:07 am

Post by tjm215 »

thats what im trying but when I have the knob controlling the feedback also controls the effect level when I try that

heres the relevant part of the code im working on

Code: Select all

ldax adcl
rdax fbk,1
wra delayl,0

cho rda,RMP0,REG|COMPC,delayl 
cho rda,RMP0,,delayl+1 
wra temp,0 
cho rda,RMP0,RPTR2|COMPC,delayl  
cho rda,RMP0,RPTR2,delayl+1 
cho sof,RMP0,NA|COMPC,0 
cho rda,RMP0,NA,temp 

wrax fbk,0
rdax fbk,1
mulx pot1

wrax dacl,0
frank
Posts: 1244
Joined: Wed Oct 19, 2005 12:26 pm
Contact:

Post by frank »

Do you want the pot to control both? If not then do the mulx at the top where you read the feedback not at the bottom where you write it to a register. Basically:

.
.
rdax fbk,1
mulx pot1
wra delayl,0
.
.
.
wrax fbk, 1.0
wrax davl, 0
Frank Thomson
Experimental Noize
tjm215
Posts: 18
Joined: Sun Dec 22, 2013 8:07 am

Post by tjm215 »

ok Ive got this and im still having the same problem. no sound with pot1 turned all the way down

Code: Select all

lldax ADCL
rdax fbk,1
mulx pot1
wra delayl,0
cho rda,RMP0,REG|COMPC,delayl 
cho rda,RMP0,,delayl+1 
wra temp,0 
cho rda,RMP0,RPTR2|COMPC,delayl 
cho rda,RMP0,RPTR2,delayl+1 
cho sof,RMP0,NA|COMPC,0 
cho rda,RMP0,NA,temp 
wrax fbk,1 
wrax DACL,0 
frank
Posts: 1244
Joined: Wed Oct 19, 2005 12:26 pm
Contact:

Post by frank »

Look at the first three lines of your program and think about what is happening to the accumulator.
Frank Thomson
Experimental Noize
tjm215
Posts: 18
Joined: Sun Dec 22, 2013 8:07 am

Post by tjm215 »

aha! got it! thanks a million frank

Code: Select all

ldax adcl
rdax fbk,.6 
mulx pot1
rdax adcl,1
wra delayl,0 
cho rda,RMP0,REG|COMPC,delayl 
cho rda,RMP0,,delayl+1 
wra temp,0 
cho rda,RMP0,RPTR2|COMPC,delayl 
cho rda,RMP0,RPTR2,delayl+1 
cho sof,RMP0,NA|COMPC,0 
cho rda,RMP0,NA,temp 
wrax fbk,1 
wrax DACL,0
frank
Posts: 1244
Joined: Wed Oct 19, 2005 12:26 pm
Contact:

Post by frank »

Close, and will sound almost right but remove the first 4 lines and replace with:

ldax fbk
mulx pot1
rdax adcl,1
Frank Thomson
Experimental Noize
tjm215
Posts: 18
Joined: Sun Dec 22, 2013 8:07 am

Post by tjm215 »

Great thanks. I'm not sure I notice much of a difference but it saves me a line of code so I'll take it. Thanks a lot frank
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