For my planned DXpedition to Malawi (7QNL, May/June 2014) I made an Artisan (Win)Keyer
to be used in conjunction with N1MM-logger. This contrapsion works very well (at home/on the bench).

However, when abroad, what happens if the Arduino ‘resets’/stops/<fill in another issue> ?

Of course the Arduino IDE is present on my laptops, and issues may be ‘programmed away
on the fly’.

But…  what if the hardware (e.g. on the Arduino board itself) malfunctions?

OK, take/bring another Arduino (of course). But what if this one fails too (for whatever (same) reason)?

A priori, ‘Plan B’ is mandatory. Actually, ‘plan B’ nowadays equals ‘plan A’ in Madagascar (5R8NL) 2007:
Use the same (serial) port for both CAT (‘frequency administration’) and (CW) keying the transceiver,
in conjunction with a separate (hardware Boolean OR’ed) keyer (I have envisaged)

In 2007 (5R) a default laptop owned a ‘decent’ RS232 interface, and I designed a RS232-compatible
CAT + CW interface (using two transistors as levellers and inverters) for my rig. It performed well.

Nowadays USB rules.

A few months ago I ordered some ‘FT232RL’ USB-interfaces (from Ebay) to program Arduino Pico’s.
The FT232RL chipset is interfaced to my rig in an utterly simple manner: just connect the wires.
No MAX232′s, no inverters, no levellers, no optocouplers, no PCB designs, etc..

Repeat, connect the proper (RX/TX/DTR) wires …  (provided your rig has TTL-inputs/-outputs).

For whatever reason I cannot not get ‘CTS’ (= ‘PTT’) working (perhaps one of the 3.3 / 5V pads have to
be shortened on the USB-FT232RL interface board?) and DTR keys the rig, and when I send the software
‘PTT command’ in N1MM-logger to my rig everything works well, also sequencing (the amplifier) <– most important!

DTR of the FT232RL chip is configured as ‘CW’ in N1MM-logger, and is ‘interfaced’ through a diode (BAT86).

That’s all (for ‘Plan B’) from 7QNL/ PA3FYM

Below a picture of ‘Plan B’ (no…, no casing –> casing = weight. Cable tie is  … handy ; -)
(click on image to enlarge in a new tab)