ESP8266 Community Forum

- Fri Jul 31, 2015 9:10 am #24705 Here is how I wire up my devices including voltage dividers to ensure that I convert 5V TX from UART to 3.3V RX into ESP. Obviously no need to worry about 3.3V output from ESP TX.

http://neilkolban.com/tech/wiring-up-esp8266s/

Free ESP8266 book available for download here.

- Fri Jul 31, 2015 2:15 pm #24730 Thanks a lot, I will try to implement level shifters

- Fri Jul 31, 2015 4:56 pm #24738 OK , as I've pointed out the problem, can you answer my question too if you know.

I don't understand why the TX/RX do not need to be crossed either doing it that way whereas the direct ftdi cable must be crossed . perhaps the lines are crossed on the Arduino board. What affect on those lines does taking the processor out have.

I notice on the R3 version of Uno there are 1K resistors on the lines already between the ATMega16U2-MU which is the UART but the lines are not crossed and are fed to the microprocessor pins in parallel to the output pins as I see it .

Last edited by tytower on Sat Aug 01, 2015 4:32 pm, edited 1 time in total.

Get you modules here:

https://www.banggood.com/custlink/KvGGhGF4wG

- Fri Jul 31, 2015 5:34 pm #24741

If your Arduino or USB adapter is 5V, you MUST use level shifters. The ESP is 3.3V and has 3.3V inputs are not 5V 'friendly'. I use several ESP-07 and ESP-01 boards running at 3.3V using level shifters to a 5V USB adapter and still works fine, never bricked one.

I might add, that's a matter of opinion . I ran 3 of my ESP12 chips directly from a 5V FTDI cable for a week with no bad results that I saw then and they have been running for 3 months now without fault.

I don't promote doing that, as I did it by accident, but its not the great fearful thing it is made out to be for ESP12's at least and the chip is the same on all the boards.

Using a resistor inline reduces the voltage . You can calculate how much 2K takes it down if you have a scope . I don't and it can't be the bricking cause because the output from the Arduino Uno 's UART is not high enough and the 2K resistance takes current down too .

You might also note when making these wowser all encompassing statements that the ESP's pins have a 6V snapback protection circuit to protect it from electro static discharges which implies it should be safe to use up to 6V and above as it should disconnect itself at the 6V level.

Get you modules here:

https://www.banggood.com/custlink/KvGGhGF4wG