While it's curious why UDOO went with 3.3V instead of 5V (five being required to drive most servos directly) I was wondering which specifically are special restricted to 3.3V? I'm hoping the other connectors are to standard .. so for example MIPI CSI-2 connector is standard, HDMI is 1.3 or 1.4 compliant, and LVDS to spec (anyone know which)? I'm asking so that I can rest assured that it is just the Arduino compat J21, J17, J5, J8, J23, J11, and J15 I/O pins I need to be careful about 3.3V? Anyone know for sure?
Yeah it's just the Arduino-related pins that are 3.3V. They used the Due as the model for the Arduino side (rather than the Mega). I think (don't hold me to this) the newer ARM-based SAM3 chips only do 3.3V vs the older Atmel chips used in the Mega. Basically it's a trade off - you have a MUCH more powerful processor with more memory space and such driving the arduino side than you'd find in the Mega, but you have to live with the 3.3V instead of the 5V. Over in the 3D printing thread, I posted this link: http://forum.arduino.cc/index.php?PHPSE ... =136717.30 Basically we're not the only ones who have issue with the 3.3V setup. It's a pretty big group of folks who are turning down the Due for the 5V of the Mega or are looking for ways to bridge 3.3V<-->5V. If somebody could put together a good translation shield I'd be happy to use that, and that's what the thread I linked to is discussing, so I think it'll happen. It's just a matter of time. If you only need to convert a couple pins at a time then that's pretty straightforward (Adafruit.com has some voltage level convertors for both digital and I2C interconnects that come to mind.) --Mike
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Thanks Mike. I was actually thinking a shield so glad to hear that has some traction already. Also glad to hear that adafruit.com has some V converters that might fit the bill. Might be good for the up to half dozen servos I was thinking about. I realize there are always trade offs in the decision making process and I'm just glad to hear that the other connectors don't have oddities/special considerations.
personally, I would just use transistors for the servo's (signal excluded), but I guess it depends on what you're building (it is good enough for my project, but I only will need 1 or 2 servo's) but yeah if you indeed will need about half a dozen servo's then maybe it is easier to use a specific shield for this or something like it edit: do you really need 5v for a servo signal? I would think 3.3v be sufficient and just power the servo itself from another source or something like that.
There's a level shifter shield available from Digistump on preorder. It's for their DUE clone, but should be compatible with the UDOO as well.
@mozer - good call. I'll probably just power the servos from separate power and link the grounds. Thanks.
@anlumo - yeah I saw that, but it only does the original arduino pins, not everything on the Due... But better than nothing.
If you have any special requirements, you should create your own shield anyways. It's trivial to make a level shifter using MOSFETs or the TXB0108. For a lot of servos, there's also the Adafruit 16-Channel 12-bit PWM/Servo Shield.
I actually spoke with the Udoo guys at their booth @ Maker Faire in NYC over the weekend. This subject came up and they indicated that they're working on a "converter shield" to convert to 5V. They're hoping to have it out in October. So there IS hope, and it would appear they're actually monitoring these threads and listening to what we're saying (which is awesome BTW!)
a UDOO team member had already mentioned they are working on a converter shield a while back on Kickstarter: With the higher resolution DAC and ADCs of the Due I would have thought that the Arduino team would put something out by now for higher precision. But its great that the UDOO is on top of it.
