ESP8266 Community Forum

- Fri Jan 09, 2015 6:46 am #6786 Hello, I have a little problem with communication via hardware serial port. I testing the communications via prolific USB-serial with free wire and this is fine. But when I want to use hardware serial port I can't connection with the module.


I replace TX and RX wire from USB to Serial behind hardware serial and it is problem. I have hardware button for restart. When I press the button the blue LED on modelu stay shine. The communication look like this:



Do you have any tip what is wrong? I tried change baud rate, replace RX-TX.

- Fri Jan 09, 2015 5:44 pm #6861 Typical ordinary COM (RS232) from PC (DB-9) connector uses voltage levels:

-12V - LOW (0)
+12V - HIGH (1)

ESP8266 uses LVTTL levels:

0V - LOW (0)
3.3V - HIGH (1)

So probably you fried ESP8266 if you connected ESP with typical RS232 without level converter.

If ESP8266 still works with Profilic, you must use for example MAX3233 based converter to use with ordinary COM (RS232) connector.

- Wed Jan 14, 2015 1:15 pm #7303 Hello Adex, thanks for your help. I buy PCB with the based converter and I will test it.