ESP8266 Community Forum

- Thu Dec 10, 2020 4:28 pm #89742 Hello,
I bought an arduino beginer kit some years ago, and now that I have time (thx covid ) so i'm learning how to use it.

I played with the arduino uno, leds, serial, etc... and now I want to use my esp8266 (esp01) to play with my home Wifi. (with no idea on what I will do in the end).
So I plugged my esp to my computer via the arduino uno (in reset mode).
I can see in the serial the initialisation of the esp (and blue led light for 0,1 second) :


After that, I have no more communications with the esp. All AT commands I send makes no answer. And leds stay off. I red Somewhere that when we flash a custom program to the esp he doesn't respond anymore to AT commands, maybe the esp comes to me with a custom program ?
I can connect to the Wifi ssid "AI-THINKER_8F1852", created by the esp, but nothing else. In addition that's not really what I wanted, since i want the esp to connect to my existing home wifi.

So i decided to try to flash an official program, to enable the AT commands.
I followed 2 tutorials, very similar. the best of them was this one :

https://www.instructables.com/Flash-or-Upgrade-Firmware-on-ESP8266-ESP-01-Module/

But I cannot get any result when the flasher try to "sync" with the esp :

I connected all esp pins as shown in the linked tutorial :
3.3V for vcc, ch_en;
GND for gnd, rst, io0
tx -> tx , rx -> rx (as the arduino is in reset mode) (I step down the RX to 3,3v with 3 resistors)
io2 unplugged
I have a feeling that the reset pin does nothing when I put it on GND for 2 seconds, and then unplug it.

To conclude :
I can't send AT commands
I can't flash a new software (one official)
So I don't know how to interract with the esp (except connect to his wifi, and then nothing)

Thank you for all advices, I hope my work with the esp will not stop now.

PS : i have some more information on serial when i plug the esp and immediately unplugged it. If that can help :
20:05:30.382 -> 2nd boot version : 1.5
20:05:30.382 -> SPI Speed : 40MHz
20:05:30.382 -> SPI Mode : DIO
20:05:30.382 -> SPI Flash Size & Map: 8Mbit(512KB+512KB)
20:05:30.382 -> jump to run user1 @ 1000
20:05:30.382 ->
20:05:30.429 -> Fatal exception 0(IllegalInstructionCause):
20:05:30.475 -> epc1=0x4020bc60, epc2=0x00000000, epc3=0x00000000, excvaddr=0x00000000, depc=0x00000000
20:05:30.475 ->
20:05:30.475 -> ets Jan 8 2013,rst cause:2, boot mode:(3,6)

- Tue Dec 29, 2020 9:09 pm #90003 Maybe too late as I just see this post, but check the baud rate, for some weird reason the flash app defaults to 1152000 ... yes it has an extra 0... change it to 115200 and will work.

Good luck.

- Thu Dec 31, 2020 8:10 am #90024 thank you losephus1976 for your help, I didn't saw the extra 0!

There must be another problem because it stays on "sync".

I changed the resistors of the RX channel, i tried 3x 220 Ohm, and 3x 10kOhm without any result.
The 220 seems to draw too much energy from the rx pin on the arduino, because the tension between rx and ground were below 5v, and so below 3.3v at the esp rx pin. With the 10K ohm I have the right tension (5v at the arduino, and 3.3 at esp).

I join 2 photos of my assembly :



thank you again for your help.

- Thu Dec 31, 2020 8:46 pm #90028 to use the uno for flashing the esp you need to keep the atmega328 in reset or remove it from the socket