ESP8266 Community Forum

- Mon Dec 21, 2015 3:02 pm #36918 Are you sure that TX/RX are connected properly ?
Normally, blue LED is the ESP TX, so if you are sending something and it light up, this means you RX/TX should be crossed :

ESP RX <-> FTDI TX
ESP TX <-> FTDI RX

- Mon Dec 21, 2015 7:23 pm #36927

I went back to attempting communication with a Raspberry Pi and connected it as follows.

....
Reset on ESP to GND
....

No matter which terminal program I use, I still get the same result. The blue LED flashes when I try to send a command, but no response on the terminal.

Are you keeping RESET connected to GND constantly?? it will never boot in that case. You reset it by touching to GND temporarily, then let go. It has a pull-up internally that will pull itself back up to ~3.3V.

So try disconnecting your RESET pin from GND. Then connect via UART, and type AT. It should echo back your commands if you are using AT command fw at 74880 baud. If you don't have firmware installed you will get something like this on the UART: "ets Jan 8 2013,rst cause:2, boot mode:(1,7)"

The reset pin is this pin shown below as RST:

- Tue Dec 22, 2015 12:04 pm #36968

I went back to attempting communication with a Raspberry Pi and connected it as follows.

TX on ESP to TX on Pi
RX on ESP to RX on Pi
Reset on ESP to GND
CH_PD on ESP to 3.3V
ESP GND to Raspberry Pi GND and external power supply GND

No matter which terminal program I use, I still get the same result. The blue LED flashes when I try to send a command, but no response on the terminal.

I would have connected:
TX on ESP to RX on Pi and
RX on ESP to TX on Pi

- Tue Dec 22, 2015 3:53 pm #36983

Are you sure that TX/RX are connected properly ?
Normally, blue LED is the ESP TX, so if you are sending something and it light up, this means you RX/TX should be crossed :

ESP RX <-> FTDI TX
ESP TX <-> FTDI RX

I tried it both ways. When in this configuration, I get the flashing blue LED when I try to sent a command. If I send AT I don't get the "OK" response.
ESP TX <-> FTDI TX
ESP RX <-> FTDI RX

If I do this configuration I get no indications.
ESP TX <-> FTDI RX
ESP RX <-> FTDI TX

The same thing happens with the Raspberry Pi.