ESP8266 Community Forum

- Fri May 15, 2015 1:10 pm #17494 Hi, I am new to this module ESP 01
I have connected the module as follows :
Vcc 3.3V
CH-PD 3.3V
RST floating
GPIO1 Gnd
GND Gnd
GPIO2 floating
Tx - to Rx (pin2) of DB9 connector
Rx-to Tx(pin3) of DB9 Connector
I am using Nodemcu for firmware update
I have selected the correct COM port since the log displays that the port is connected.
Also it shows that it is finding ESP8266
The blue icon keeps rotating. But the firmware is not flashed
The DB9 male connector is directly connected to the DB9 female connector on the CPU motherboard.
Can someone please explain as to why the firmware isn't getting downloaded?
Is an FTDI programmer necessary or I can directly connect the Rx, Tx and Gnd pins to the TX, RX and Gnd pins of the DB9 and flash the firmware?
Thanks,
Tanmay

- Fri May 15, 2015 1:51 pm #17495 Hello Tanmay,

I'm sorry but that is not going to work. The DB9 is some form of RS232 which differs from TTL serial expected by the ESP8266. Here is explanation: https://www.sparkfun.com/tutorials/215

That is why everybody uses the USB/Serial adapters. On ebay or aliexpress search for "USB Serial", most are just a dollar or so.

Good luck!!
John

- Fri May 15, 2015 3:04 pm #17498 Hi,

the DB9 connector of your motherboard has +-12V level, which is by far too much for the ESP. It needs a 3,3V level. It's rather probable, that you've blown up the ESP. Use either a level shifter or much easier a USB-serial chip like FTDI or better PL2302.

BR
kubi

- Sat May 16, 2015 4:09 am #17538 Hi,
I have used a MAX232 IC for communication. The communication seems to be working now.
Status of LEDs at Power ON:
red led : constatnt ON
blue led: flashes once
Status of LEDs when Flash is clicked in NodeMCU firmware
red led:constant ON
blue led: flashes continuously
When flash button is clicked, the blue Icon rotates continuously but the progress bar is blank.
I tried connecting RST to Gnd momentarily, as well as swapping RX, TX. Also I changed baud rate from 9600 to 57600 of COM port.
But the firmware doesn't seem to be getting downloaded.
Any suggestions?
Thanks,
Tanmay