| Author |
Message |
Uncle Krunkus
Moderator
Joined: Jul 11, 2005
Posts: 4761
Location: Sydney, Australia
Audio files: 52
G2 patch files: 1
|
 Posted: Tue Oct 14, 2008 12:13 am Post subject:
|
  |
|
| urbanscallywag wrote: | Cool.
9 flip flops for the main counter, and 13 flip flops for the outputs. 10 flip flops left.
Excuse me while I brush up on some fancy combinational logic...or switch to FPGA.  |
I didn't want to rain on your parade here either, but I think you've underestimated the number of flip-flops needed. Each note will need it's own dedicated set of flip-flops as they are all reset at the end of each cycle, ie; you can't use some flip-flops to divide by one integer while some of them are being shared to divide by another integer, let alone sharing them across 12 notes. I estimate almost 108 flip-flops needed, not the 32 you've quoted above. I could of course be wrong, I have been before!  
_________________
What makes a space ours, is what we put there, and what we do there. |
|
|
Back to top
|
|
 |
urbanscallywag
Joined: Nov 30, 2007
Posts: 317
Location: sometimes
|
| Posted: Tue Oct 14, 2008 9:43 am Post subject:
|
|
|
No rain there, I am in agreement with you. I was probably unclear. 
I only estimated 22 flip flops, not 32 which is the number in the smallest CPLD.
The number I came up with was only based on the main 9-bit counter and flip flops on the actual output of each of the 13 divided clocks. I skipped the magic in between, showing that there were only 10 flip flops left in the smallest FPGA to actually derive each of the 13 output signals. So unless someone does some pretty fancy combinational logic it cannot be done with the remaining 10 flip flops.
The number you came up with is more realistic and closer to what I came up with. The $12 CPLD quoted above was done with these "proper" calculations. |
|
|
Back to top
|
|
|
urbanscallywag
Joined: Nov 30, 2007
Posts: 317
Location: sometimes
|
| Posted: Tue Oct 21, 2008 10:57 pm Post subject:
|
|
|
BOB-SNARE/anyone: If you're interested in keeping PLCC-44, why not divide the design into multiple pieces/chips? Luckily there is no reason the signals couldn't come from 2 or more CPLD.
I would opt for a large QFP and PCB if I were doing the design, but that would require the CPLD to be soldered and programmed by me, raising the price. It would be small and elegant though. |
|
|
Back to top
|
|
|
BOB-SNARE
Joined: Sep 26, 2008
Posts: 30
Location: Australia
|
| Posted: Wed Oct 22, 2008 5:34 pm Post subject:
|
|
|
| urbanscallywag wrote: | BOB-SNARE/anyone: If you're interested in keeping PLCC-44, why not divide the design into multiple pieces/chips? Luckily there is no reason the signals couldn't come from 2 or more CPLD.
I would opt for a large QFP and PCB if I were doing the design, but that would require the CPLD to be soldered and programmed by me, raising the price. It would be small and elegant though. |
Like I said before , I have been able to fit the 8-bit TOG into a single PLCC44 package.
I've simulated and synthesized and routed the design in the xilinx webpack. I just need to order the parts (and JTAG programmer or make a CheapTag programmer).
I'm still thinking about some optimisations for the 9-bit version, but it may need to be in 2 PLCC44 CPLDs.
I suppose it comes down to what DIYers want. TOG and Octave dividers in an all-in-one solution or just the TOG as a MK50240 replacement (at 5V). |
|
|
Back to top
|
|
|
urbanscallywag
Joined: Nov 30, 2007
Posts: 317
Location: sometimes
|
| Posted: Wed Oct 22, 2008 6:42 pm Post subject:
|
|
|
I think integrating the octave dividers makes sense, a half-CPLD half-CMOS approach seems like you should just be using all CMOS.
I will have to go back read what the differences in precision of the 8 and 9 bit counters are.  |
|
|
Back to top
|
|
|
theshaggyfreak
Joined: Oct 29, 2006
Posts: 48
Location: Centreville, VA
|
| Posted: Thu Oct 23, 2008 11:15 am Post subject:
|
|
|
Hey, if anyone is interested, I have a couple of 50240's that were purchased at Radio Shack in the 80s still in the blister packs. Anyone want to make me an offer?
_________________
Shaggy
http://www.pureshift.com
http://www.bsodmusic.com |
|
|
Back to top
|
|
|
richardc64
Joined: Jun 01, 2006
Posts: 679
Location: NYC
Audio files: 26
|
|
|
Back to top
|
|
|
Scott Stites
Janitor
Joined: Dec 23, 2005
Posts: 4127
Location: Mount Hope, KS USA
Audio files: 96
|
|
|
Back to top
|
|
|
|
Forum index » DIY Hardware and Software
FAQ
Calendar
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
Chat Room
