Looper's Delight Archive Top (Search)
Date Index
Thread Index
Author Index
Looper's Delight Home
Mailing List Info
[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Date Index][Thread Index][Author Index]

Re: question for Mathias Grob,regarding pcm42 mod

maneco from uruguay:
>>>i have two questions regarding your primitive loop delay,based in 
>>>pcm42 and counters,registers...
>>>i've read the program code in your site..did you do all of that 
>>>just with logic?
>>>in that case, you used presetable counters or adders for 
>>>calculating the read and write address...
>>
>>correct
>>
>
>do you remember which counters you used(my guess is 74ls163 for 
>presetable counters,and 74ls283 for adders...)

I dont remember. 163 seems right...

>Is it necesary to work with the full adress,or just the most 
>significant part of it,for example the 8 most significant?

I am not sure whether 8 are enough. 265 stepps seems little. Depends 
on memory size. The least 4 bits are not interesting at all, if you 
dont mind to loose some resolution, you can cut another 3-4.

>i'm starting to understand all of your system,but i don't quite get 
>the idea of how to make a difference using logic 
>gates(radr=wadr-lotm,for example)maybe i should think it as 
>wadr=radr+lotm?

I dont think I used HW adders. But they are capable of doing 
differences, you just have to invert one side, probably its even 
possible with some control bit...

Anyway, you can save the adress at StartRecord and load it as 
ReadAdress at StopRecord into a separate counter. Multiply similar...

>i'm not asking for your designs or drawings,i'm really having fun with 
>this...

ok, I let you figure it out. I am not sure whether I have a drawing 
of the 42 mod and if so its in Brasil, so I can only look it up in 
the middle of September.

>i'm happy that i understood how you copied the data from the tempo 
>loop to the long multiplied loop,it's not a copy,just full 
>feedback,isn`t it?

thats right, you only have to jump correctly with the read address.

>my looper is getting into shape...4mb,30khz,8 bit + 
>compander,stompbox format,four footswitches(tap,loop,write and 
>bypass)later i'll have to think how to send clock out from it,maybe 
>with a pll(4046?)i'll have to multiply the tempo rate from the tempo 
>count
>
>obrigado!!!
>
>Maneco


-- 


          ---> http://Matthias.Grob.org