Once the serial output interface has proved the feasibility, it is time to test the input serial interface of command.

The magic of the modular design is that it is .... modular.
To test the serial rx of command, what can we do?
A remote IR or 433 MHz RF control.

Everybody has an old unused remote control. So we need only a pro mini as usual and an IR receiver or with a kit like https://fr.aliexpress.com/item/Hot-Selling-1pcs-New-Infrared-IR-Wireless-Remote-Control-Module-Kits-For-Arduino-Wholesale/32334118062.html?spm=2114.06010108.3.20.dks3Id&ws_ab_test=searchweb0_0,searchweb201602_4_10065_10068_10084_10083_10080_10082_10081_10060_10061_10062_10056_10055_10037_10054_10033_10059_10032_10078_10079_10077_10073_10070_10052_423_10050_10051,searchweb201603_9&btsid=eab7add7-3d55-47c9-a695-3a0112ac058f

May be, I will do it one day or other...

I will thanks here the 11 paypal donator s
Be sure that I will improve this project until I am alive (and have some spare time).
Yes, It it motivating