next topic »

[on:]

With the release of the Leonardo recently, we see the Arduino team's choice of going with the ATmega32u4 as a much more superior and cheaper alternative to the Atmega328 for various reasons which I won't go into here.

While I agree with most of the reasons, my one main gripe with the choice is the fact that the microcontroller is an SMD as opposed to a through hole. Here're the problems that I see with that choice:

• Prototyping: Becomes difficult. Can't use a breadboard to prototype a standalone with the microcontroller
• Reuseability: With the UNO, I could use the same board to push a bootloader onto a new $3 ATmega328, flash a program and use it in a standalone stripboard. Can't do the same with the ATmega32u4. I'll need to buy a new $25 Arduino board and solder it into the project I wish to make

These are problems a newbie, the Arduino's target audience, is likely to face since SMD soldering isn't as easy as through hole soldering.

Again, while I do understand the benefits of the choice, I don't really have much of a need of most of the features it provides. I'm sure there would be a few others also with the same problems. Can these be resolved with the leonardo? For example, is there a through hole variant for the ATmega32u4? I could continue using the Uno, as I will at the moment, but is there any other way?

[Reply #1 on:]

"we see the Arduino team's choice of going with the ATmega32u4 as a much more superior and cheaper alternative to the Atmega328"
That is way too broad of a statement.  That all depends on the application, doesn't it?

If your design does not need PC connectivity, then the USB support is not worth the extra $2/chip at all.
http://www.mouser.com/ProductDetail/Atmel/ATMEGA328P-PU/?qs=K8BHR703ZXhdUS2n3IW%2fRITwfrPGjO%2fc
http://www.mouser.com/ProductDetail/Atmel/ATMEGA32U4-AU/?qs=SSucg2PyLi6%252btEjw08wzMxwto7OuSeUW

If what you really need is a 2nd hardware serial port for other uses, then  324/644/1284 might be superior.
http://www.mouser.com/ProductDetail/Atmel/ATMEGA324PA-AU/?qs=nE%2fgAoToukEcKrza3XGz%252b9gY2ASxR6oY
http://www.mouser.com/ProductDetail/Atmel/ATMEGA1284P-PU/?qs=K8BHR703ZXhm9eu3oaOLPZcUMbiBTz4d

"is there a through hole variant for the ATmega32u4?"
Nope.

"is there any other way?"
Get some breakout boards to use the '32U4 as a DIP component. Adds a little to the cost of the hobby.
Make it a custom board with USB connector and xtal/caps/resistor to end up with a little module, sort of like a nano.
I have a board that does just that, with a buffer and uSD socket on the bottom of the board. See my signature link.

[Reply #2 on:]

"we see the Arduino team's choice of going with the ATmega32u4 as a much more superior and cheaper alternative to the Atmega328"
That is way too broad of a statement.  That all depends on the application, doesn't it?

I meant the Arduino product itself (the "Arduino"), they're selling a board with more capabilities at a price that's cheaper by $10. But your point is well taken.

The breakout board is a good idea. But I don't think you can burn a bootloader onto the MC on a breakout board and then pull it out and use it elsewhere.

[Reply #3 on:]

"we see the Arduino team's choice of going with the ATmega32u4 as a much more superior and cheaper alternative to the Atmega328"
That is way too broad of a statement.  That all depends on the application, doesn't it?

I meant the Arduino product itself (the "Arduino"), they're selling a board with more capabilities at a price that's cheaper by $10. But your point is well taken.

The breakout board is a good idea. But I don't think you can burn a bootloader onto the MC on a breakout board and then pull it out and use it elsewhere.

No you cant burn a bootloader and swap chips, unless you build a board with an expensive zif socket for the qfp chip, but you can solder the bare chip to your board and either include a isp header pads (with or without the header itself) or connect the isp programmer using microclips to program the bootloader...

[Reply #4 on:]

Or connect the programmer to the SPI pins that you are likely to have available at the IO connectors anyway, same as one would on a promini.

$10 cheaper?  Maybe some places. Certainly can find them with a much smaller spread. Or Uno's for less even.
I see Uno R3s for $22.45,
Leonardo with headers for $22.95,
Pro328 (like Uno with no header) for $19.95, (well, no onboard USB, so not really I guess)
Leonardo with no header for $20.

They're effectively all the same price for now.

http://store.nkcelectronics.com/arduino-diecimila.html
http://store.nkcelectronics.com/Arduino-Leonardo-with-Headers_p_361.html

http://store.nkcelectronics.com/arduino-pro-328--5328516.html
http://store.nkcelectronics.com/Arduino-Leonardo_p_360.html

I guess with the Leonardo, there's really only 1 chip to break on the board, vs the uC and the USB/Serial interface.
Only 1 chip to program at the factory too, so one would think the price for Leonardo's could improve some more.

The only drawback I see is losing FLASH memory for the USB interface.  Maybe it fits in the normal bootloader space. I'm not that up on the USB equipped chips yet.

[Reply #5 on:]

I don't see the Leonardo as a replacement or an improvement over the UNO. I think it's just different - an additional product in the lineup.

If you want something you can prototype on an Arduino board then rebuild on a breadboard or perfboard, use the UNO. If you need the USB functionality, or need a few more analog inputs, try the Leonardo. Different tools for different jobs.

BTW the USB files do take up a bunch of flash space in the Leonardo. The virtual serial port is in both the bootloader and duplicated in the core files. So where they both start with 32kB of flash, the UNO only loses 512 bytes to Optiboot, but the Leo loses about 7kB between the bootloader and the USB files that get included in every sketch.

On the flip-side you get 512bytes more SRAM on the Leonardo. Different tools.

[Reply #6 on:]

I guess with the Leonardo, there's really only 1 chip to break on the board, vs the uC and the USB/Serial interface.
Only 1 chip to program at the factory too, so one would think the price for Leonardo's could improve some more.

Possible I guess, once they get some efficiencies in the manufacturing process.

I don't see the Leonardo as a replacement or an improvement over the UNO. I think it's just different - an additional product in the lineup.

I hope so. The way it's being shown around gives me the impression that they're going to replace the Uno with it.

Losing 7KB of flash memory out of 32KB is a lot. That's a 20% reduction in the space. There should be so many projects requiring USB functionality to justify that much space, I'd say at least 50% of the projects made using the board.

[Reply #7 on:]

I hope so. The way it's being shown around gives me the impression that they're going to replace the Uno with it.

Even if the official Arduino Uno goes away and they switch to SMD chips, that doesn't prevent building homemade Arduino's with DIP chips.  And it is unlikely the cloner's will ever stop producing the DIP versions--at least while there is still demand, which I don't see going away anytime in the foreseeable future.