RS232 UART Acceptable Voltage for ESP32

[DanMars]

Hi All,

I have a project to have an ESP32 talk to a RS232 device. The device is powered by 12 volts, and the RS232 specs indicate the voltage can be as high as +-15v. I assume I cannot wire the TX/RX wires directly into the ESP32 pins for the chosen UART as 12V will probably fry the ESP32. Or will it? What's the best practice for this? Perhaps there is a level shift chip that works for 12v to 3.3v?

Thank you for any insight.
Dan

[ESP_Sprite]

The GPIOs of the ESP32 indeed won't be happy if you stick 12V on them. The more-or-less canonical solution for this would be a MAX3232 or equivalent, fed off the same 3.3V the ESP32 is powered by.

[DanMars]

Thank you for your help. I will look into those options.
Dan

[shyney]

Thank you for your help. I will look into those options.
Dan

Did you find a solution for this? The Datasheet of the MAX3232 Chip says:

Accepts 5-V logic input with 3.3-V supply

so I guess 12v logic from the RS232 Device is not acceptable...

[ESP_Sprite]

Did you find a solution for this? The Datasheet of the MAX3232 Chip says:

Accepts 5-V logic input with 3.3-V supply

so I guess 12v logic from the RS232 Device is not acceptable...

You wouldn't apply the 12V RS232 signal to the logic inputs, you would connect them to the RS232 line data inputs, and those do accept 12V.