ESP8266 Community Forum

- Mon Oct 23, 2017 7:20 pm #71151 I have a bunch of ESP-01s modules I'm having wireless connection issues with.

If I simply power the ESP up with 2 D cell battery or a level shifting adapter board with 3.3V regulator, the module powers up and connects to my AP very quickly. If I connect the TX pin to a level shifting circuit or directly to the TTL PIC RX, the ESP almost never connects to my AP and falls-back to its internal AP mode.

Pins 5-reset, 4 PIO-2, 6 PIO-0, are floating on my adapter board. On some sites I see pins 7,5,3,2, tied high. Pin 6 & 4 high with a 10K pull up resister. Is there any general rule of thumb what to do with unused pins?

Also in my case pin 3 CH_PD is tied high directly to VCC. I see some application use a pull-up resister some do not. Is there a general rule of thumb for the enable input?

- Wed Oct 25, 2017 8:07 am #71206 This is what I think and only based on observations and not looking at any code.

I think the serial port is set up by default. In that case a normal state would be for RX to be high. If it isn't high then there is an error condition. I think as long as that error condition persists the code will keep waiting.

I have found that I need to have RX high on ESP boards that do not have a serial line attached. I normally include a pull up resistor on RX on my boards.

@OldPCGuy The enable pin can be directly connected to VCC. A pull up resistor on that pin allows it to be normally high but still used on designs that might require it. I have a couple of projects that run on batteries and I use the enable line to disable the module.

- Wed Oct 25, 2017 7:10 pm #71218

Do you use Serial at all? I don't because I use both TX and RX as GPIO pins...I noticed that if TX is HIGH at powerup, the 01s won't boot normally... Wondering if there is something special about TX/RX that (when "interfered" with) cause some kind of timing issue at startup? i.e a bit like pin 16 on other boards is not the same "spec" as a "normal" GPIO?

How long does your code wait (max retries?) before you fall back to APmode?

AP fallback is after ~20 seconds. I didn't write the firmware so I'm not sure on the retries.

The ESP firmware is written to accept E1.31 serial data over wireless then transmit out TX to the PIC. Other than negotiating the lease, I/P, pwd etc. the communication is more one way PC>>AP>>ESP>>controller.

There is alternate firmware I can try that outputs on GPIO-2.

So if data is output over TX, RX should be set high? If data is output over GPIO-2, RX and TX should be set high? Would it hurt to try?