[arm-allstar] Why Arduino?

[David McGough]

Hi Guys,

The reason for the Nano is simple: The I/O pins on the BBB/RPi/RPi2/RPi3 
boards are VERY delicate--I know this from personal experience!  Most pins 
on the expansion bus on these boards are directly connected to the 
SoC (the microprocessor). There is no buffering, no surge protection, 
nothing. These boards use 3.3V logic, accidentally tie 5V to a GPIO 
pin--POP! Too much accidental RF nearby--POP! Buy a new RPi3! ...Or, even 
worse, the RPi2/3 becomes a "walking wounded" ---it's not completely dead, 
it just exhibits sporadic flakiness.

Compared to the RPi2/3 I/O bus pins, the USB bus on these boards is 
extremely robust. Since USB is intended to be connected to user 
peripherals, the signaling is well protected.

Also, some users have mentioned GPIO via the parallel printer port 
interface found on legacy systems...Well, similar to USB, the PP Port is 
intended to be connected to user peripherals. It includes VERY robust 
buffering and surge protection.

After over a year of trial, error and discussion, I happened across the 
Nano boards for another project. The Nano worked so well that I evaluated 
it as an I/O solution for AllStar. And, if an accidental "oops" does 
occur, at under 1/10 the cost of a RPi3, they are more than slightly 
cheaper!

73, David KB4FXC



On Tue, 6 Dec 2016, "David Lang via arm-allstar" wrote:

> On Tue, 6 Dec 2016, "Thor Wiegman via arm-allstar" wrote:
> 
> > The Arduino thing sounds cool but it leaves me with a question:  Why use an 
> > external microcontroller for this instead of the Raspberry Pi's GPIO?
> 
> It boils down to the fact that they are afraid that hooking up to the Pi GPIO 
> pins could fry the Pi if you either wire something wrong or too much RF gets 
> into the wires.
> 
> The same thing could happen to the Arduino, but if it does, you fry a $3 module 
> instead of a $35 module.
> 
> I'm not sure I agree with their choice, this is either going to work or it 
> isn't. If it doesn't, then frying modules will result in unusable systems 
> (albeit slightly cheaper to replace)
> 
> I'm hoping that once they actually release the code (and this release process is 
> far to much like proprietary software to make me happy), I'm hoping that some 
> people will hack it to support the native GPIO pins instead of requiring the 
> external box/board.
> 
> David Lang
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