oachkatzalschwoaf / SerialChiller

A wireless RS232 adapter for the Internet of old things.

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ESP32 and MAX3232 based wireless RS232 adapter for the Internet of old things.

Build video

DuinoDCX Demo Video


The wiring is implemented as DTE. RS232 TX and RX are connected to the default Serial2 pins IO16 and IO17. RTS is connected to IO21 and CTS to IO22.


Part Value Package Part #
C1 0.1uF C0603 C0603X104K5RAC
C2 0.1uF C0603 C0603X104K5RAC
C3 0.1uF C0603 C0603X104K5RAC
C4 0.1uF C0603 C0603X104K5RAC
C5 0.1uF C0603 C0603X104K5RAC
C6 22uf A/3216-18R T491A226M010AT
C7 22uf A/3216-18R T491A226M010AT
C8 22uF C1206 LMK316ABJ226KL-T
C9 0.1uF C0603 C0603X104K5RAC
C10 0.1uF C0603 C0603X104K5RAC
IC1 LM1117IMPX-3.3 SOT223 NCV1117ST33T3G
MAX3232 MAX3232CSE SO16 MAX3232IDR
R1 10k R0603 NRC06J103TRF
RS232 56F402-001 56F402-001 56F402-001
S1 B3U-1000P SW_B3U-1000P B3U-1000P
S2 B3U-1000P SW_B3U-1000P B3U-1000P
SERIAL Serial 1X02 pinhead
VIN Power 1X02 pinhead

PCB Thickness

Use 0.8mm thick pcb to make the board align horisontally with the case.

Other components


The plastic housing is taken from a cheap vga break out board available from multiple different vendors. Search eBay or Aliexpress for DB15 breakout.

USB to TTL Cable

USB to TTL serial adapter cable for powering and flashing the board.

Strain Relief

Print the strain_relief.stl out of any plastic material to properly secure the cable to the housing.

Cord Sleeve

The black 4mm cord sleeve is available from multiple different vendors. Snip the end off to make it fit. Search eBay or Aliexpress for 4mm cord sleeve or 4mm strain relief.


Make sure that the thumb screws are properly tightened or remove them completely. A loose thumb screw may short circuit the electronics.

When used with an extension cable the thumb screws can be replaced with #4-40 jackscrews.

Power Supply

Any standard usb charger will work fine. The average power consumption is under 500mA.

Example projects




Creative Commons — Attribution 4.0 International

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A wireless RS232 adapter for the Internet of old things.

License:Creative Commons Attribution 4.0 International