Why not a voltage selector on the Arduino board?

Other Hardware General Electronics
21

5V shield only ruins your day if you power it from 5V.
So power it from 3.3V instead and all is honky-dory.

Now we have the reverse problem to a short time ago. Previously, some vendors were selling
shields, like for XBee and SD cards, that did not have 5V-to-3.3V level-shifters on them, and
people were blowing up the XBees and SD Cards. So, the vendors finally came around to
redesigning the shields better.

So, maybe the shields should have the 5V vs 3.3V option, then the DUE is safe. Can of worms.

22

CrossRoads:
5V shield only ruins your day if you power it from 5V.
So power it from 3.3V instead and all is honky-dory.

So any active components on any specific legacy 5 volt shield will run at 3.3vd? Also there is still 5vdc on the 5V shield pin even on a Due board, so any old 5 volt shield will still run at 5vdc just due (no pun) to the fact that it's mounted to a Due board.

Gives me an idea for a DUE shield. Bring all pins in, but only 3.3V for power. Any device must be 3.3V device.

Easy to design a shield for Due use only or for Uno use only, trying to get a shield compatible for both is what we are asking about.

2nd shield - Bring 5V in, but provide offset female headers that are all 3.3/5V buffered with TXB0108 chips or equivalent. Fully compatible with 5V shields, but only 3.3V is exchanged with the DUE.

Maybe, not familiar with that TSB0108 chip. Does it support the high output current that a 8 bit AVR output pin can supply?
Lefty

23

"Maybe, not familiar with that TSB0108 chip. Does it support the high output current that a 8 bit AVR output pin can supply?"
TXB010x would be for logic level translation of control lines between Due IO and 5V devices on the shield.
http://www.ti.com/product/txb0101
Also available with 2,4,6,8 buffered lines:
txb0102
txb0104
txb0106
txb0108