I'm trying to understand the REF pins by reads and I've assumed my own thoughts for lack there of.

The AREF and REFIO are for analog and digital pin interrupt respectively duplicates the entire bay of pins to having their own full set of usage of analog and digital for a usage of it's own, during interrupt cycles between the Arduino being the bus (also needs interrupt, on slave and master situated to all devices connection) and another device, any one to many that also make use of INT0 & INT1 and a REF?

That seems consistent with explanations not really resulting in solid understanding uniformly said, for instance the voltage throughput explained is a variant low spectrum of voltages (as if someone projected interruption was failure applying ON for the entire reference bay new) that which must current the full circuit disposition during interruptions because it's not exacting time, in speed of electricity pausing cycling circuit halts. Therefore establishing stable circuitry with non stable pin complimented what actually occurs on the bays in extremely quickly volt changes, things more fractional of current then then a half of off to on, that's called pulling up, and on each pin at the same time for the whole A or IO bus.

So in general post I'm sort of asking what your thoughts are on that, if you have a exampled use or you see the same sort of theorized mentions that some what stay estranged but not false?

In a global memory sense of interrupt nature a circuit doesn't use any more resource for the amount of connected, only slows the more that are, their just cycle one Arduino, so long as they are designed to properly poke and peek on and off at INT0, INT1, AREF and REFIO in proper interrupt communicate (which Windows 95/98 liked to get in trouble with constantly). Like a P.C. a graphics card talks to the monitor directly, and so on through what ever device it is that is it self a function for in any situation so I suppose it's more a hardware thing.

But I'm guess... I like my guess though.

According to the schematic for the Uno IOREF is directly connected to the 5v pin.

AREF is for an external voltage reference for the analog to digital converter. The Atmega 328 datasheet will have all the details.


Yeah, okay, well if anyone knows of any examples of projects complete in information to the effect try out the use of, that is really what I suppose I’m posting about in query. I’ll check that out. I obviously don’t have a need for it when never figured out how to, but curious as it appears to tbe the only pin I’m not familiarized with on any Ardunio I have.

On the Uno, AREF is an open pin with a capacitor to Gnd.

Internally the pin connects to the Analog Input multiplexer.

The default setting for the ADC comparison voltage ie External, which routes the AVCC signal thru the mux. The cap on AREF thus helps the voltage to be stable, and perhaps less noisy.
When Internal is selected, the 1.1V internal voltage reference is routed instead.

I'm not sure what to select to use neither AVCC or the 1.1V reference and to use a voltage applied to AREF instead.

The IOREF pin was intended to provide the IO level being used on the main board to any daughter boards, so they could supposedly supply 3.3V signal or 5V signals on their IO pins. I am not personally aware of any shields that can switch back and forth.

Forget about interrupts and what else you have mentioned.

The Aref pin on an Uno is nothing more than the ability to gain access to the reference voltage of the A/D converter.
It is normally internally switched to VCC (default 5volt Aref).

It can be switched to an internal 1.1volt reference voltage, or it can be internally disconnected so you can connect an external reference voltage to it.

IOREF is nothing more than a connection to VCC (the power supply) of the processor, 5volt on an Uno,
so a connected shield knows what logic signals to provide or to expect.
You can use this pin as a 5volt pin, in case you need more.

A Due (3.3volt logic) has IOREF connected to the 3.3volt VCC.