ESP8266 Community Forum

Hi Experts,

I tried to talk to my new ESP8266 12F using two different serial cables (prolific USB-TTL and Moxa UPort1150 with level shifter). I also tried to flash with NodeMCU with their ESP flasher and also tried to talk with ESPlorer. I installed the ESP tools onto my Raspberry and used its UART port.

In all of the above I got a timeout when I asked the MCU but when I applied reset the blue led lit on then got the same answer, something like this:
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The enable pin is on Vcc 3.3V, reset pin is on Vcc via 10k, power is currently via serial cable (but tested with external supply as well with a max. capacity of 800mA). I tried with all serial speeds but the above answer was consistently found only on 115200. There was a quite similar thread under the http://www.esp8266.com/viewtopic.php?p=31006#p31006 but nothing else.

I bought 10 MCUs and tested with three. All of them gave me the same reply as above, so I think I have something wrong on my side. The serial communication works fine and I was able to upload NodeMCU to an another ESP8266 (like this: https://www.banggood.com/ESP8266-10A-220V-Network-Relay-WIFI-Module-Input-DC-7V30V-p-1089200.html?rmmds=search)

Thanks for your help,
zsszucsi

Some updates: grounding of GPIO15 (UART0 RTS) improved a little, I can communicate but only for a short period of time. After a few seconds I have to reset the MCU because the serial communication is still noisy, and kills the link.

(If you check the schematics above, do not use the GPIO9 for 1 wire communication, like to talk to a DS18B20. I moved it to GPIO5)

This looks a lot like the initial comms on first boot...

I don't know how much you have played with the ESP8266 but the initial baud rate of the serial line when it is first booted is 76800 - it uses this rate to print out the initial boot status, and then will switch to your selected rate.

Have you tried listening to this at 76800? It's not a standard baud rate (it's tied to the crystal freq)

to put it simple: your circuit is rubbish.

look at the (proven good) examples on the board. Capacitors and pull up/down resistors are not surplus, they are relevant. Read some more threads on what combinations of gpio 0,2,15 are necessary for which action.
If you know a pin may not be used, why interfere by connecting it somehow?