Re: Clone Raduino ?

Jerry Gaffke

Any vendor that supplies an Arduino Nano with header pins already soldered in place
will have them on the "pin direction wrong" side for our use.  The trick is to buy one without
the pins already soldered down.  To plug the Nano into a Raduino board, we need to have
the pins on the same side as the USB connector.

Blindly plugging in a Nano that has pins on the wrong side
means power and ground got applied to the wrong Nano pins.
Mostly likely destroyed the Nano.

Originally, the Raduino came with the Nano soldered in place, mounted under the LCD display.
There was no room under that LCD display for a socket, which was bad news because
we were seeing a fair number of Nano failures.
The solution was to socket the Nano on the other side of the Raduino board,
out from under the LCD display.
That change was made when the v4 uBitx came out.

Having the big 12 and 16 mhz crystals as pointed to by Snowist's yellow arrows
is slightly better for v5 in that those quartz crystals are more stable then the 
cheap ceramic resonators found on most $2 Arduino Nano clones.
However, not much of anything in our radio depends on those crystals being accurate,
a CW keyer might be at 20.1 WPM when it claims to be 20 WPM.
(The operating frequency is determined by a 25mhz crystal on the Raduino, not the Nano.)
On v3 and v4 a Nano oscillator that is exactly on frequency can beat with our 12mhz BFO
and create audio tones, so the (most likely) off frequency ceramic resonators are
perhaps preferred.  On v5 the 12mhz BFO was moved to 11.052mhz to completely
avoid those audio beat notes that a few v3 and v4 users reported hearing,
so not an issue there.

Jerry, KE7ER

On Tue, Apr 2, 2019 at 02:51 PM, Snowist wrote:
I will show you anexample. I have 3 different Arduino Nano boards (I use them for experimental purposes)

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