mega16->smaller package

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I have a lot of C legacy code for the atmega 16. For a new design I'll need to recycle some of it into a smaller package.

Any suggestions for a chip with register compatibility and fewer pins? SMD preferred. Code space is not very relevant. I'll run it of 3.3V.

What I'll be using are UART, 2-wire, a timer and SPI. The timer code will be new.

Thanks,
Borge

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Are you using the DIP package now? Can you go to an SMD package? How small do you need to go, you really didn't say much.

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Quote:

Any suggestions for a chip with register compatibility and fewer pins?

Well, there are very few AVR models with full "register compatibility". So tell more about what you mean by that.

Porting to e.g. a Mega48 (one thing you didn't mention are the memory requirements--flash, SRAM, EEPROM) would require examining all I/O register usage. Perhaps especially the port pins.

Now, let's start at the title. "smaller package". What package are you using? What is your desired size?

The Mega16 comes in 44A at 12mm x 12mm and the 44M1 at 7mm x 7mm. Is the newfangled Mega164 any smaller? (the porting will be much simpler) Lessee--that does indeed come in the 44MC package at 5mm x 5mm. See the datasheet.

Mega48 family has 32A at 9mm x 9mm. 32CC1 at 4mm x 4mm. 28M1 at 4mm x 4mm. 32M1-A at 5mm x 5mm.

So if the 44M1 is7mm x 7mm and the 32-M1-A is 5mm x 5mm, would the board space savings be worth the porting effort? Or are you better off just using the Mega16 in one of the available packages? It might be critical if making "motes", but in a general app?

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Thanks for the input. I'm using the atmega16 in TQFP44 today. Ideally, I'll bring 2-wire, SPI, UART and a timer to a package with fewer pins. 4k of code will probably be OK.

TQFP I can hand solder, but QFNs can be tricky. Same applies for packages with an exposed center pad.

I also have legacy code for the atmega48 for the functions I need. The atmega48 in TQFP-32 might fit.

Borge

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If package size is important you are probably designing your own PC boards. If you are going to the trouble to have PC boards made up then for a "few bucks" more you could also have a solder mask stencil made up. With the use of a stencil you can lay down solder past and then soldering QFN or even BGA packages becomes do-able. You can use a common hotplate to flow solder such packages easily. www.sparkfun.com has some on line videos and tutorials on how to do this.

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ATTiny4313 is 3x3mm

No RSTDISBL, no fun!