Ideas for Uno/Mega and perhaps other boards.
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Weather Guy
Jun 17, 2016, 8:53:52 AM6/17/16
to Developers
Hi,
I've been playing with some ideas for tweaks to the Arduino boards. I thought I would throw these out there to see if anything sticks. If you're not interested, that's okay too.
1) Remove the ceramic resonator and associated parts from main processor and replace with buffered clock output (CLKO) from USB processor (8U2 / 16U2). This has the benefit of providing a more accurate crystal-controlled clock to sketches which require accurate timing. It also eliminates a couple of components. It requires a complete re-layout of the board however to have any hopes of meeting FCC emissions limits. Both the 8U2/16U2 and main processor must be rotated 90 degrees to get the two pins carrying the 16MHz clock close to each other -- the resulting short trace and careful attention to AC grounding should have a good chance of passing FCC tests. I have done sample layouts for both Uno and Mega showing that this component placement is feasible.
2) Replace the existing 150mA 3.3V regulator with a 500mA regulator (Texas Instruments uA78M33CDCYR). Larger package but same price in quantity, and there seems to be room on the boards for it.
3) Replace the VIN linear regulator with a 1.2A buck-mode switching regulator. This allows the board to run from DC inputs as high as 24V without the worries of overheating. I tried to do a price comparison in quantities between 1k and 3k. The price for the current design comes out to $0.91US and the new idea comes out at $0.99US. That's my best guess at the cost difference. There is of course the need to re-test for FCC emissions limits with this option. Because this increases power efficiency you could sell it as a "green" feature. I have done sample layouts for this idea and it seems to fit on the boards okay too.
In summary, above are three options to consider for the future. I'd be glad to discuss any of these in more detail. If you're not interested...then never mind ;-)
Cheers,
I've been playing with some ideas for tweaks to the Arduino boards. I thought I would throw these out there to see if anything sticks. If you're not interested, that's okay too.
1) Remove the ceramic resonator and associated parts from main processor and replace with buffered clock output (CLKO) from USB processor (8U2 / 16U2). This has the benefit of providing a more accurate crystal-controlled clock to sketches which require accurate timing. It also eliminates a couple of components. It requires a complete re-layout of the board however to have any hopes of meeting FCC emissions limits. Both the 8U2/16U2 and main processor must be rotated 90 degrees to get the two pins carrying the 16MHz clock close to each other -- the resulting short trace and careful attention to AC grounding should have a good chance of passing FCC tests. I have done sample layouts for both Uno and Mega showing that this component placement is feasible.
2) Replace the existing 150mA 3.3V regulator with a 500mA regulator (Texas Instruments uA78M33CDCYR). Larger package but same price in quantity, and there seems to be room on the boards for it.
3) Replace the VIN linear regulator with a 1.2A buck-mode switching regulator. This allows the board to run from DC inputs as high as 24V without the worries of overheating. I tried to do a price comparison in quantities between 1k and 3k. The price for the current design comes out to $0.91US and the new idea comes out at $0.99US. That's my best guess at the cost difference. There is of course the need to re-test for FCC emissions limits with this option. Because this increases power efficiency you could sell it as a "green" feature. I have done sample layouts for this idea and it seems to fit on the boards okay too.
In summary, above are three options to consider for the future. I'd be glad to discuss any of these in more detail. If you're not interested...then never mind ;-)
Cheers,
Gabriel Staples
Jun 19, 2016, 4:37:12 PM6/19/16
to devel...@arduino.cc
Those are all very interesting ideas, and they sound well thought out to me. I'd like to hear what some of the other experts think, like perhaps Massimo Banzi, Paul Stoffregen, or other hardcore developers and creators.
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Clovis Fritzen
Jun 20, 2016, 4:17:38 AM6/20/16
to Developers
Nice work in there!
My input to the points you raised are:
1) I do not think Arduino.cc still wants to mess around with the ATMEGA328 anymore; implement the CLKO idea doesn't seem to be the kind of effort they want to go into (specially because I see a move from 8-bit to 32-bit (ARM) and said processors have different clocking modes, some of them even work very nice with internal clocking).
2) Using linear voltage regulators is in the past now (unless they don't want to go the "extra mile" in that direction, what I find unlikely), so replacing a LDO by another doesn't seem a good idea.
3) They are already using a buck circuit on Arduino Zero, but I don't know further details about part number, etc. In that same line: what could be done is to exchange both 5V and 3.3V power regulators with buck converters (the same chip with two different outputs, perhaps?).
Regarding the "green future" you mention, I don't think Arduino.cc would sacrifice simplicity (cheap buck converters or linear regulators) solely to make a "green board"; that could be true for high-end products (Arduino 101, etc) but not for the low-end low-cost low-complexity Nano, Zero and Gemma for example. Looking at their philosophy, I don't think they put "high power efficient boards" over "easy to use" or "low complexity" ones.
TK
Jun 24, 2016, 3:47:42 AM6/24/16
to Developers
I also like the suggestions of Weather Guy, he has done good research.
on the comments of Clovis Fritzen:
on the comments of Clovis Fritzen:
1) I do not think Arduino.cc still wants to mess around with the ATMEGA328 anymore; [...] I see a move from 8-bit to 32-bit (ARM) [...]
Why should they want to move from 8 bit to 32 bit on Uno and Mega? Isn't 8 bit just that kind of simplicity why so many like these boards, and what you mention yourself at the end of your post?
Of course, most of the users work with c++ when programming Arduino, so it doesn't matter that much to them what MCU is used. But I can think of others, who will want to have the same simple MCU on these boards, and maybe a 32-bit MCU on another one, as an additional type, but no replacement.
Of course, most of the users work with c++ when programming Arduino, so it doesn't matter that much to them what MCU is used. But I can think of others, who will want to have the same simple MCU on these boards, and maybe a 32-bit MCU on another one, as an additional type, but no replacement.
2) Using linear voltage regulators [...]
3) They are already using a buck circuit [...]
I definitely would appreciate buck converters a lot! I have embedded an Arduino Uno into another circuit recently, which was running at 24V. Having a regulator which supports a wide-range input voltage (6-26V) would have removed the need to add a converter (230V~ to 9V=) by myself for the board only.
The "green feature" would be a positive side-effect, but not the reason for the change. It would also keep the need for additional cooling at low or zero level if the board is encapsulated into a thight housing and running under full load.
The "green feature" would be a positive side-effect, but not the reason for the change. It would also keep the need for additional cooling at low or zero level if the board is encapsulated into a thight housing and running under full load.
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