ESP8266 Community Forum

I have this all running ,connecting to a modem and posting data to Sparkfun .

What I don't understand is when powered through my USB port of my computer and FTDI cable giving 3.3 V the blue LED shows no light until it posts .

When I use a power supply like a battery or a wall wart through an Adafruit breadboard power supply kit giving 3.3 V the blue LED is often slightly lit and flashes when posting as usual .

It still seems to be doing what its supposed to do but I can't fathom the difference . What would cause that?

I watched it some more in the dark . After a reset when it starts it comes on for a couple of seconds and after the deepsleep() reset it lights dimly for about 2 minutes of the sleep time and then goes out for the last minute of the deepsleep() which is 3 minutes in total.

I thought it might be the capacitor I have on the XPD----||----RST line which was pretty big but I changed that to a very small value with no effect on the LED.

martinayotte wrote:Yes, the Blue LED is connected to the UART TX ...

So it must be transmitting something during deepSleep() ?

Thinking a bit more about this . The device puts out a serial communication after each reset I think and I wonder if its trying to send this serial data for a predetermined time because the TX and RX lines are not connected in my application.

EDIT I found that what i thought was a 3.3V FTDI cable was a 5V giving out 4.76 V .so thoght that perhaps this was related in some way but the esp showing the blue light was doing so on a 3.3V adafruit power supply so I doubt its the excess power.

On my ESP07 blue LED is connected to GPIO1 (which is also UART TX line). So, if you don't plan on using serial comm, or use UART2 (Serial2) this LED can be driven low to turn it on.