One day I noticed, that arduino pro mini are quite cheap for everyday stuff.
It’s very small, and to keep lower price, this Arduino does not have USB interface.
On ebay it’s ~3$:
For writing sketches to this Arduino, bought CP2102 USB to UART brige:
It’s easy to connect. Arduino has few pins with the same name, so You may choose any of them.
I personally didn’t even solder that additional part of arduino mini pro in front, as same pins were on side anyway.
CP2102 Arduino mini pro
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GND GND (green wire)
VCC VCC (blue wire)
TX0 RX1 (grey wire)
RX1 TX0 (violet wire)
DTR +||- RST (capacitor between pins 0.1-1uF) (orange, capacitor, then red)
Also both ends on arduino: VCC with RST via 10-12Kohms resistor. (just resistor between pins)
Mine, easy to setup for code uploading:
