Back in the old days, before USB, we had to use RS-232 to communicate with computers. One of our first designs was the ATmex (https://www.ladyada.net/techproj/Atmex/index.html), a microcontroller board with a built in bootloader! We used the MAX232 (https://www.digikey.com/en/products/detail/texas-instruments/MAX232DR/555684) to convert 5V serial to +-10V RS-232.

These days, with USB-Serial converter chips like the FT232 or CP2102, you'll still see remnants of that past, such as DTR and RTS pins. When working with retro or industrial equipment, you may still find RS-232 DE-9 connectors.

Let's take a look at some 3.3V-friendly transceivers, and find one that can do the full 5/3 pin-complete DE-9 connection set.

See the chosen parts on DigiKey here https://www.digikey.com/short/218mnb89

Visit the Adafruit shop online - http://www.adafruit.com

-----------------------------------------

LIVE CHAT IS HERE! http://adafru.it/discord

Subscribe to Adafruit on YouTube: http://adafru.it/subscribe

New tutorials on the Adafruit Learning System: http://learn.adafruit.com/

-----------------------------------------