SerialChiller

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

<img src="https://i.imgur.com/FYeBvYt.png" width="480"> <img src="https://i.imgur.com/sKjFjxz.jpg" width="480"> <img src="https://i.imgur.com/4ShiExd.jpg" width="480">

Build video

Wiring

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.

Partlist

| 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 | | ESP-WROOM-32 | ESP-WROOM-32 | ESP-WROOM-32 | ESP-WROOM-32 | | 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

Case

<img src="https://i.imgur.com/vMuh47L.jpg" width="300">

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

<img src="https://i.imgur.com/Rv4BXdY.jpg" width="400"> USB to TTL serial adapter cable for powering and flashing the board.

Strain Relief

<img src="https://i.imgur.com/pojF2cD.png" width="400"> Print the strain_relief.stl out of any plastic material to properly secure the cable to the housing.

Cord Sleeve

<img src="https://i.imgur.com/vxLgsbd.jpg" width="200">

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.

Installation

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.

<img src="https://i.imgur.com/62l8ALO.jpg" width="400">

Power Supply

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

Example projects

https://github.com/lasselukkari/DuinoDCX

https://github.com/AlphaLima/ESP32-Serial-Bridge

License

Creative Commons — Attribution 4.0 International