Why in the world would anyone set analog in voltages as 1.8V??? Everything I have and know about uses 0-5V.
I freely admit I am a complete newbie at the BeagleBone Black (BBB), but come ON.
I have an unverified theory that circuitry in the processor chip is unable to handle 5V in, but couldn’t they have used a wider trace or something?
I purchased 2 BBB’s to use on for monitoring engine temps (4), 3D positioning, G-forces experienced, and airspeeds. All my A/D chips output 0-5V while only a couple support I2C. I was all excited about the BBB until I actually spent nearly $300 only to find out it’s major limitation. I assumed EVERYONE in the embedded world worked on 5V analog in, like Arduino and Raspberry Pi.
Does the Arduino have I2C?
Lots of reading seems to indicate, also, that not many versions of Linux or Android for BBB support graphics acceleration in hardware that is available in the BBB.
Allow me to add an example: AD594 and AD595 thermocouple chips output the temps in a 0-5V range.
The ADCs are designed for resistive touchscreen interfacing. 1.8V consumes less power than higher voltage and 1.8V was good enough for touchscreens.This isi a limitation of the processor, not the design of the board. The board was designed to meet the capability of the processor.
Gerald
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Why in the world would anyone set analog in voltages as 1.8V???
Everything I have and know about uses 0-5V.
...
Allow me to add an example: AD594 and AD595 thermocouple chips output the
temps in a 0-5V range.
The operating voltage is determined by the semicondurctor technology used
to make the CPU chip. The latest high performance chips use high-density
processes that can make lots of very tiny transistors, but the down side is
that the features (gates) of those transistors are very thin and can't take
large supply voltage, which determines all other operating voltages used
by this chip. Since the power consumption turns out to depend on the squae
of the supply voltage, lowering the chip operating voltage is inevitable,
and 5V hasn't been seen on such chips in a long time.
You can reduce the voltages from the outside of your system down to what
BBB can take by a variety of active or passive voltage dividers; the
simplest one would just consist of two resistors, say 2.2kOhm and 4.7kOhm
in series connected between the ground and your analog voltage. You then
connect the top of the 2.2kOhm resistor to the analog input of the BBB. 5V
should get divided down to 1.6V, which should be safe for BBB (this assumes
that your analog has low impedance, and BBB input impedance is high enough)
Having said that, you should brush up on electronics if you want to do such
analog interfacing. It's not rocket science, but if you don't know the
basics there's a gazillion ways in which you can damage your BBB.