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For discussion of Speeduino compatible boards designed / built by other members of the forum and for guidance around making such a board
User avatar
By PSIG
#9357
The potential of board designs with the ATmega integrated (not shielding an Arduino Mega) is of interest, and also the opportunity to migrate to the ATmega2561 processor. In-general—is this possible for future versions of Speeduino or related projects such as GPIO? In other words; is it as simple as pin reassignment?
:?:
David
By noisymime
#9359
To the best of my knowledge, the bootloader and code should be directly compatible between the 2560 and 2561. The only real differences that I can see are the more limited I/O, which shouldn't really be a problem as there's plenty left.

No idea what the cost is like between the two, might be worth some investigation. QFN64 (used by the 2561) is a PITA to solder by hand though, so that might be a consideration.
User avatar
By PSIG
#9360
Cool. I'm also looking at the -16AU (TQFP-64) version, and just fewer unused legs to deal with. Though using hot air, toaster or hot plate, it shouldn't be a problem either way. Thinking perhaps a version (v0.5?) board, and it comes with only the ATmega pre-soldered. All else through-hole as now. Saves bulk, connections, simpler layout, and similar cost. One step closer to the SMD version, while ST and IDC versions unaffected but shrunk. ;)

David

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[EDIT] Or things like these could be sourced or designed, but integral seems more attractive and simpler.
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By noisymime
#9362
Whilst an all-in-one board with the MCU included does make for a more 'professional' package, there are some things to be said for keeping it off board.

First is cost, which can be worked around to an extent, but the crazy thing is that I can still buy whole Arduino Mega boards (That include the USB interface) for the same or less than I can get just the atmega2560 IC. There's no worry about flashing bootloaders or choosing which USB option you go for.

The other is that if you do something stupid and fry an input (for example) or something, all you need to do is replace the arduino rather than messing around with trying to swap the IC.

Not saying this isn't something to look into as it definitely makes for a good package, but there are pros and cons.

(TQFP-64 is FAR easier to work with than QFN64 too, so that's a good choice. I missed that the 2561 came in that package).
User avatar
By PSIG
#9403
noisymime wrote:Not saying this isn't something to look into as it definitely makes for a good package, but there are pros and cons.
True that. Still thinking at <$4 in under 10 quantity, it may be useful for daughter boards. A $2 USB UART makes a package. Any special considerations for pin reassignment, or just find a similar type pin and designate it in code? Would be nice to be able to select 2561 for code option, but have not done this before, so need some basic guidance.

David
By noisymime
#9415
PSIG wrote:Any special considerations for pin reassignment, or just find a similar type pin and designate it in code?
Only for the crank and cam inputs, they must be attached to the hardware interrupt enabled pins. You'll have to read through the datasheet to figure out which ones they are on the 2561.
By NickZ
#9448
Where can i buy 2561 for under $4? i would like to try them out, im happy to make up the boards to try.

Edit.
I found 20 for $26AU, i wonder if they will work?
By klotzy_550
#9463
I too was looking at the 2561 and through mouser it costs just as much as the 2560, however I have been sourcing the 2560's through aliexpress for ~$3.50 USD per chip. All have worked thus far.
By NickZ
#9466
Aliexpress is where i found the 2561 20 for $26 and free delivery, sounds too cheap but will see.
I guess i will have to convert the port numbers to correspond to a Arduino pinout so i know what pins to set in the Firmware or is there a easier way?
By noisymime
#9468
NickZ wrote:Aliexpress is where i found the 2561 20 for $26 and free delivery, sounds too cheap but will see.
I guess i will have to convert the port numbers to correspond to a Arduino pinout so i know what pins to set in the Firmware or is there a easier way?
You're free to use any ports you want as new pin mappings can be added fairly easily. The only exception to this are the crank/cam (and soon to be flex) inputs as they must be attached to one of the pins that allows for external interrupts.
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