New CPU Project

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helyx525
 
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Re: New CPU Project

Post by helyx525 »

I think we are starting to settle on the AVR2561. If anyone has a better suggestion, now is the time to discuss it.

Our next milestone is to make prototypes. To get there, we need to:

1) Design and layout the daughterboard. I will start working on a rough schematic and hopefully one of you can do the complete schematic and a layout.

2) I can get the prototype PCBs made here in the US. ExpressPCB.com will make us 3 boards, 2.5x3.8" size for $17/board. If anyone can beat that, let me know.

3) Buy the parts. My back of napkin estimate is $30 per prototype.

4) Assemble/test the prototypes. I will donate my time to do the assembly myself. Anyone that feels confident soldering an SMD CPU is welcome to try their hand at the DIY route.

Assuming I wont need to make more the 9 prototypes, people involved in the "New CPU" or "New Firmware" projects can each buy one prototype for the cost of the board and parts.

After that we can spend some time improving the firmware and adding cool features. Once we have a compelling new firmware put together, we then lobby kit vendors like WillyZ to get a batch of the boards made so end users can buy them.

Luap
 
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Re: New CPU Project

Post by Luap »

Just a thought.. (and im no electronics wiz, so bare with me!) These "bigger" cpu's have more pins right? Presumably these have potential to be utilised for something new also. So perhaps the mod pcb could have a simple breakout area for easy access to these extra pins?
That said, im not exactly sure what we could use the pins for. Perhaps some kind of led/lcd tempo display? Or other LED's that could indicate new operative modes or whatever.. Maybe something like bank 16/32 indicator led's and switch, for 32 note patterns? I don't know what's possible here though. Im just throwing the idea out there to see what you more knowledgeable folk make of it :wink:

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rv0
 
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Re: New CPU Project

Post by rv0 »

Luap wrote: That said, im not exactly sure what we could use the pins for.
first i think its important to make it work as-is with the cpu

the x0x already has plenty of buttons and leds standard (40 leds, 23 switches) and the 303 interface can perfectly be translated to it (even with the button less, it isn't that important)

you are right though that the pins should be accessible for future modders, but i guess that's the whole point of using a cpu with more pins. as long as there's enough room for it, people could do just about anything they want with those pins. it seems like a logical thing to do to push the x0xb0x project forward and if you ask me, it's looking really good if all works nicely.


so Helyx525, you'd take care of building a few prototypes for us all to test? sounds like a good idea and the price seems fair, dunno if it's beatable..

Luap
 
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Re: New CPU Project

Post by Luap »

darffader wrote:
Luap wrote: That said, im not exactly sure what we could use the pins for.
first i think its important to make it work as-is with the cpu
Oh absolutely :) Im just just thinking of some potential beneficial side effects of using these beefed up CPU's beyond storage capacity that could be put to use further down the line. With some forward thinking, we can allow room for this from the very first release of these CPU daughter boards. Hence, breakout pads.
The added storage capacity is an invitation for folk to add entirely new features/functions that the odd additional LED or button could be really useful for. This way, the user interface will still be intuitive and keeps everything pretty much instantly accessible, much like it is currently.
Without the potential for some UI expansion via those extra pins, new firmware functions may not necessarily fit in well with the current UI.
I realise a more 303'like firmware doesn't require any extra led's or buttons etc, but of course that isn't the only firmware that could live on this.

3phase
 
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Re: New CPU Project

Post by 3phase »

i would be interested in such a beta board but cant code firmware..only can test or develop ideas regarding features and handling..

regarding soldering? its a quite hard nut to solder theese micro chips...
when we need a daughter board.. arent there cpu types that can be used with a socket that has pins? would be bigger of cause, but aslong the daughter boards are not machine soldered there is a certain risk for the diy people.. i can do smd soldering and in the xox there is one part that actually is showing what kind of task we are facing here.. the usb chip..

the cpu you have selected.. has it the same formfactor or is the pin distances even smaller...

i think the formfactor of the usb chip is marking the border what one could see as a diy projekt.. actually allready slightly to small

so if there is a socket able cpu that would fit the needs it might be the better choice?

another point for the cpu selection would be to look for a widely used modell to ensure availibility for a reasonable time..
regarding the szise..
bigger should be better.. but if now everything is happening in 16 k it s maybe not necessary to beef it up to 256..
probaby ly 64 would be allready enough to achive the goals...



i also wonder about the ribon cable... why woulnt a daughter board fit on top of the exsisting cpu socket?

however.. a seperated daughter board wouldnt be a big problem..

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helyx525
 
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Re: New CPU Project

Post by helyx525 »

Luap wrote: So perhaps the mod pcb could have a simple breakout area for easy access to these extra pins?
Yup. Thats extra benefit is also part of the plan.The spare I/O pins will go to pads for modders to use.

An LCD would be a nice addition.
A 4 channel DAC could be used to form 4 CV / LFO / ENV signals.

Adding more buttons or LEDs is already possible with the current design, so no extra I/Os are needed for that. They are connected to a serial bus and its easy to add more devices to the end of the chain. Look up "SPI bus" if you want to know how that part works.

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antto
 
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Re: New CPU Project

Post by antto »

3phase wrote:...
another point for the cpu selection would be to look for a widely used modell to ensure availibility for a reasonable time..
regarding the szise..
bigger should be better.. but if now everything is happening in 16 k it s maybe not necessary to beef it up to 256..
probaby ly 64 would be allready enough to achive the goals...
...
:?
64kb is risky.. it might get too small once with start putting the good stuff in

3phase
 
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Re: New CPU Project

Post by 3phase »

I ve informed myself a bit about theese avr processors..

while there are quite a few avr´s with more flash memory that are available in a dip 40 package non of them is sharing the pin layout of the 162 used in the xox..

so a adapter board seems to be unavoidable..

I checked regarding comonly used avr´s in my local electronic shops..and the 2561 seems to be a very good choice indeed.. its so popular that its even cheaper than the smaller versions because its solld more often...

so at least from my limited perspektive i dont see anything against the 2561...


The mechanical aspects with the mentioned ribboncable stay a bit questionable for me..

beside the work aspect that everything with ribon cable is twice as much soldering points as direct solution i see mounting problems..

http://www.flickr.com/photos/ladyada/388601027
http://www.flickr.com/photos/ladyada/388602543

when you insvestigate the board of the original xox you will see that mounting points for an aditional board are not so easy to find around the processor area.. and in other areas it might interfear with other hardware mods ..

the best and easiest mounting option is the 40dip connector itself..

I think we need a solution that just can be plugged into that connector..no extra screws.. ne extra holes.. mountable for the vast majority of xox users in minutes ...

ther are however some problems..

Is it posibble to fit the 2561 between the boundarys of a 40Dip Socket?

maybe.. but that would be tight.. probably too tight...

in case its too tight, 2 suggestions..

either a double board..first form 40 dip in to something wider spaced.. than the adapter board to the 2561...

important there... the boundarys of the original xox circut board shouldnt be exceeded at any point because you dont know in what kind of housing people placed the xox board.. its only guarantied that the xox board itself fits ..
and its likely that ther is some space above the cpu.. i would estimate at least 10 mm because otherwise people get problems with the other circuit... so a double adapter board should fit...

but its twice as much soldering points.. 2 boards needs to be etched.. so basically a double price solution.. not good


The other option. something like a triangular board.. that distributes the 40 dip conection to an area underneath the switches... cheaper and easier to manufacture...

only one mechanical issue... vibration.. so the board shouldnt be too thin !

There shoulnd be traces on the side that is facing the original circuit board so some foam can be applied there..
A littel hard foam block glued just between the switch contacts should be able to support such a board enough to secure against vibration and would be easily removable in service cases.. should be possible without such a support anyway..

It would be just important than that the 40dip socket is not just a cheap one as suggested in the ada fruit part list .. It has to be a high quality one with the tight gold contacts because they hold the chip or extension board much tighter..
So tight thats difficult to remove them.. you know the type

no extra support necessary..

So i would actually opt for an adapter board that fits into the 40 dip socket made in a way that the actual cpu sits in an area outside the dip connector above the switches...
While additional pins or soldering points for additional sit wright above the conector, or very close by, to reduce vibrational loads of external cableing..

This package comes with the advice to exchange the 40 dip conector against a high quality one.. or even gets delivered with it... and maybe a small suportiv hard foam block..

Because the cpu sits outside the conector area it would be also possible to secure the additonal board with a foam block that sits directly above the 40 dip connector area and pushes against the housing of the xox... nothing too tight.. just to hold it in place so vibrations cant pull it off ..

But I dont think that this is necessary. If the board dont vibrates in itself it should be safe... so no super thin board material..
Last edited by 3phase on Wed May 19, 2010 4:55 am, edited 1 time in total.

3phase
 
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Re: New CPU Project

Post by 3phase »

another design hint for the extra board... as it shouldnt exceed the dimensions of the original xox board it shouldnt cover the mounting holes of the original board.. otherwise the cpu has to be removed all times the xox gets disassembled wht is not nice for the 40 dip connector...

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helyx525
 
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Re: New CPU Project

Post by helyx525 »

3phase wrote:arent there cpu types that can be used with a socket that has pins?
would be bigger of cause, but aslong the daughter boards are not machine soldered there is a certain risk for the diy people.. i can do smd soldering and in the xox there is one part that actually is showing what kind of task we are facing here.. the usb chip..

the cpu you have selected.. has it the same formfactor or is the pin distances even smaller...
The pin distance is the same as the max232 chip. 0.8mm spacing. I use the technique described here:
http://www.avrfreaks.net/index.php?modu ... tem_id=457
i think the formfactor of the usb chip is marking the border what one could see as a diy projekt.. actually allready slightly to small so if there is a socket able cpu that would fit the needs it might be the better choice?
You have a pretty good point here.
If we ever want to put the new CPU on a mainboard, DIY builders will have to solder this SMD chip, and I dont want to make this kit any harder to build.

I still want to pursue the 2561 chip first, but If we cant find a way to have the daughterboard produced, I would say the ATMega1284 may be a better choice. It has the same pinout as the atmega644, but is still not compatible with the atmega162 we have in there now. On the plus side, the 1284 has 128k flash, it comes in the DIP40 package and it goes up to 20MHz. On the negative side, its brand new and seems to be backordered for a month, and we would be sacrificing the extra I/Os for modders and the JTAG connector for debugging.
I also wonder about the ribon cable... why woulnt a daughter board fit on top of the exsisting cpu socket?
Willyzyx and others have said that space is too tight in that spot in the case to fit a board and connector. I wont be able to tell till my x0x arrives.

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helyx525
 
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Re: New CPU Project

Post by helyx525 »

3phase wrote:another design hint for the extra board... as it shouldnt exceed the dimensions of the original xox board it shouldnt cover the mounting holes of the original board.. otherwise the cpu has to be removed all times the xox gets disassembled wht is not nice for the 40 dip connector...
I agree the mounting holes should not be covered, but they do give me some ideas for how to secure the daughterboard.

3phase
 
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Re: New CPU Project

Post by 3phase »

Helyx525 wrote: Willyzyx and others have said that space is too tight in that spot in the case to fit a board and connector. I wont be able to tell till my x0x arrives.

thats not true.. the board just needs to sit tight on the conector and everything like additional connectors and the chip itself need to be placed more to the center of the unit..

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dnigrin
 
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Re: New CPU Project

Post by dnigrin »

You guys should touch base with Brian BANNED (bcbox) - I've sent him a PM alerting him of the thread if he's not seen it already. He just finished a daughterboard for his full x0xi0 mod that was required to isolate the mixer section from other stuff, to minimize noise. I only bring it up because he might have good ideas about where and how to locate the daughterboard...(and also his previous work on creating a new CPU daughterboard). Although it's messy because of all the cabling involved in the x0xi0 mod, look for example at this picture, and see where he has put the small mixer daughterboard: http://alphazone1.com/x0xi0/blog/wp-con ... G_3979.jpg

Apart from this - I just want to give you guys my 100% backing and support to do this!! I think it's an exciting potential new development for the x0x. Also allow me to let people know that Dan (Helyx525) is one smart dude - I worked collaboratively with him some 15 years ago on updates to my MC-202 Hack reverse engineering project, and he knows his stuff!!

textile
 
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Re: New CPU Project

Post by textile »

I don't think size will be a problem. I think that it won't exceed the height of the existing uC by using both sides of the pcb. It will be a squeeze but it will have to fit.

We will need a "device" for eagle lay-out / schematic , I have downloaded the data sheet and will draw up a device. I have a few builds to finish so I will get it done within 2 days.

I will need to know more about the schematic needed. Basic: Adaptor to the 40 pin socket / power / clock / in outs to the leds and tacts / out put to the dac and clock / accent , and 'extra' pads, any more?


For the clock I mean 1 pulse 1 step , I don't know much about DIN . I would like to use this with modular sequencers and programmers and drive it via pulse generators etc.. this is all I require if you know how to set it up within the uC that would be fantastic!
4 DACs will be excellent!

I can supply finalized boards and will be able to sell boards at my store when all done.
I will be setting up a SMT oven for fast production of multiple boards for the DIYers who can't do SMT. I am currently using a flat solder tip for SMT for the usb which is still good.

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helyx525
 
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Re: New CPU Project

Post by helyx525 »

textile wrote:I don't think size will be a problem. I think that it won't exceed the height of the existing uC by using both sides of the pcb. It will be a squeeze but it will have to fit.
Thats good news. I was having nightmares about cpu boards rattling around loose in people's cases. :)
I will need to know more about the schematic needed. Basic: Adaptor to the 40 pin socket / power / clock / in outs to the leds and tacts / out put to the dac and clock / accent , and 'extra' pads, any more?
I will work out the new schematic. What pins on the new CPU to route to what pins on the old, how the JTAG connector will work and what ports will be extra pads.

I will try to use the same ports/pins as the existing chip uses to keep the code compatible, but no guarantees since some ports may have changed functions from avr162 to avr2561.
For the clock I mean 1 pulse 1 step , I don't know much about DIN . I would like to use this with modular sequencers and programmers and drive it via pulse generators etc.. this is all I require if you know how to set it up within the uC that would be fantastic!
Ah. I understand. You want to be able to use a pulse generator to single step the 303. Thats no problem. Dinsync runs at 6 pulses per 16th note, but I dont see why we cant have a per-pattern setting for how many clocks per step. That would also allow us to make patterns that are 32nd or 8th note per step.

I also worked out my old midi 2 dinsync/shuffle algorithm on paper again last night. We will have 12 levels of shuffle timing ranging from 1:1 up to 3:1 in the new firmware.
I can supply finalized boards and will be able to sell boards at my store when all done.
I will be setting up a SMT oven for fast production of multiple boards for the DIYers who can't do SMT. I am currently using a flat solder tip for SMT for the usb which is still good.
Thats excellent!

Textile, you will be owed a great many beers by the end of this. :)

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