ESP8266 Community Forum

- Sun Aug 06, 2017 1:00 pm #68876 Hi Everybody,
I'm a newbie in electronics in general, I made this design for atmega 328 (Arduino UNO chip) with ESP 07 for WIFI connectivity connected via logic level shiftier (BSS138 MOSFET based) and 2 voltage regulators.
is the design OK? will be any fire in my house after I turn it on?

Thank you in advance.

You do not have the required permissions to view the files attached to this post.

- Sun Aug 06, 2017 3:38 pm #68884 First the MOSFET in your level-shifter seem to be in the wrong direction. See here the 3.3V side is on the Source pin of the MOSFET :

Second, the R2 on 5V side is not needed since the TX output is not bidirectional.
Third, you are missing several PullUps/PullDown resistors :
RES/GPIO2/GPIO0 need PullUps. GPIO15 a PullDown.

- Sun Aug 06, 2017 4:07 pm #68887 As it is just 1 way from +5V to 3.3V on the serial line you can just use a simple 2 resistor divider; e.g. 2.2K in series with 3.3K to GND with junction feeding the esp8266.

Depending on what you are using the mega for it may also be worth considering eliminating that and running all the code on the esp8266. With the esp8266 arduino environment you can run most stuff on the esp8266, unless you need the more extensive IO on the mega.

- Sun Aug 06, 2017 4:14 pm #68889

As it is just 1 way from +5V to 3.3V on the serial line you can just use a simple 2 resistor divider; e.g. 2.2K in series with 3.3K to GND with junction feeding the esp8266.

Depending on what you are using the mega for it may also be worth considering eliminating that and running all the code on the esp8266. With the esp8266 arduino environment you can run most stuff on the esp8266, unless you need the more extensive IO on the mega.

Thank you for the Reply.
Regarding the level shifter, I read domewhere that the simple resistor one is slow and using a mosfet is faster and better so I tried this one. Will the resistors level shifter be ok for data rate of 4 bytes/sec?

The case why I used the atmega is that I have current sensor that is 3.3v analog output, I read that thr Analog read of esp8266 is limited from 0 to 1vdc only.
Am I right?