ESP8266 Community Forum

- Wed Nov 13, 2019 10:08 am #84548 Hello
I want to connect ESP to Arduino Nano, to send information via wifi fom arduino sensors. I want to use AT commands.

I've flashed the firmware - ESP8266_NONOS_SDK_V2.0.0_16_08_10. I have connected VCC and CH_PD to external 3.3V power supply, GND and GPIO15 -> GND, Tx -> Tx, Rx -> Rx with voltage divider to drop 5V -> ~3.3V.

I've plugged Arduino (with reset and ground connected) to computer and opened serial monitor. ESP gives me a message at baud 74880:

Code: Select all ets Jan  8 2013,rst cause:2, boot mode:(3,6)

load 0x40100000, len 2408, room 16
tail 8
chksum 0xe5
load 0x3ffe8000, len 776, room 0
tail 8
chksum 0x84
load 0x3ffe8310, len 632, room 0
tail 8
chksum 0xd8
csum 0xd8

2nd boot version : 1.6
  SPI Speed      : 40MHz
  SPI Mode       : QIO
  SPI Flash Size & Map: 8Mbit(512KB+512KB)
jump to run user1 @ 1000


but it doesn't respond to any AT commands. Any help is appreciated

- Thu Nov 14, 2019 4:37 am #84553 Can you "Talk" to the ESP directly (using a USB -> convertor) from within a program like PuTTY? Also: the ESP boots at 74880 Bd, but then switches over to 115200 Bd (or 9600 / 57600 with older firmware).

Assumption is the mother of all f*ckups. At least: that's what I'm assuming.

- Sat Nov 16, 2019 11:17 am #84575 I'm using Arduino as a converter (reset and ground on arduino short-circuited, so it won't boot), I don't have any other converter. I've tried to talk using PuTTY, at 74880, 115200, 9600 and 57600 baud, nothing happens.

- Sat Nov 16, 2019 2:00 pm #84581 From your wiring arrangement, it looks like you have incorrectly tied Rx of the esp to Rx of the Arduino Nano and Tx of the esp to Tx of the Arduino Nano. I am also using an Arduino (Uno) to talk to an ESP8266-01. I have tied Tx on the Arduino thru the 5V to 3.3v resistor arrangement you have used to the Rx pin on the ESP8266. You can tie the Rx of the Arduino directly to Tx of the ESP8266 (without the dropping resistors) because the Tx sources the power for transmit to the Arduino and the Arduino will recognize the 3.3 volt high as a logic high. I have been using this communication configuration for two and a half years without any errors with data communication multiple times each day.
Note: You cannot talk to the Arduino via USB while you have the ESP8266 connected to the Tx and Rx lines of the Arduino. If you need both serial communication links active at the same time you will have to define two new pins on the Arduino as a software serial connection and use a software serial library to make the software serial port functional. Be sure to define baud rates on both serial ports and add code for reading/writing serial from one serial port to the other write/read on the software serial port.
If you want to see my wiring diagram you can look at the August 2017 Nuts and Volts magazine "Bi-Lingual Light and Appliance Control"