ESP32 and MAX3232 based wireless RS232 adapter for the Internet of old things.
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 |
| 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 |
Use 0.8mm thick pcb to make the board align horisontally with the case.
The plastic housing is taken from a cheap vga break out board available from multiple different vendors. Search eBay or Aliexpress for DB15 breakout.
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.
Any standard usb charger will work fine. The average power consumption is under 500mA.
https://github.com/lasselukkari/DuinoDCX
https://github.com/AlphaLima/ESP32-Serial-Bridge
Creative Commons — Attribution 4.0 International