Some help with Pull-Up/Down on ESP01 ?

Other Hardware General Electronics
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ESP01-GPIO0.png

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Are you defining the GPIO2 as an output?

check this out: http://www.instructables.com/id/How-to-use-the-ESP8266-01-pins/

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Mopheus:
Hi everyone, I have a simple question but after some research online I can't still figure out the solution. Sorry for my bad english. It's quite simple, I'm using this very easy circuit to control an IR led, but when I connect it to GPIO0 or GPIO2 on my ESP, it doesn't work. While it works on GPIO3 (RX)... so, I think it's because for some reason, when connected to GPIO0 is pulling up (or down) the pin and going into FLASH mode. Is it possible ?

Can someone help me understand how to change this circuit to work with GPIO0 (is the one I need to use actually).

Thanks.

Several things:

  • How are you determining that the IR LEDs are not working? You do realize that IR LEDs are not visible, right [unless you're a snake, or a very unusual human]? Is it that you have an IR receiver, and it isn't registering? Also, a quick way to verify that the IR LEDs are lighting up [or not] is to use a Digital Camera [can be on a Cell Phone]. Most digital cameras will show IR as a "color" [usually a pinkish white]. First, power up an IR LED using a DC voltage and a resistor [run it at 20mA, unless you know for sure it is rated to run at a higher continuous current]. Then, using the camera, peer down at it from the top. If you see a glow, then you have verified that your camera can, indeed, "see" IR. Then, do the same with the IR LEDs you are driving with the 2N2222.
  • You show 50mA as the current at the collector. Using an LED forward voltage of 1.1V, I get more like 79mA:

[5V - 2(1.1V) - 0.1V]/34Ω = 79.4mA where: 1.1V is the IF of each LED and 0.1V is the VCE(sat) of the transistor.

BUT, that's assuming a VCE(sat) of 0.1V. Even if the VCE(sat) is more like 0.3V, and each LED VF is more like 1.3V, I still get around 62mA:

[5V - 2(1.3V) - 0.3V]/34Ω = 61.8mA

So, are you over driving those LEDs. And could that have fried them?

  • Are the LEDs being held on for too long? Typically, such high currents are meant to only be applied for short periods, with a small duty cycle. Have you consulted a datasheet, and are you driving then correctly? This could be another reason the LEDs could have fried.
  • If you have a scope, take a look at the is happening across the Collector-Emitter junction. Do you see it toggling? If not, do you see a signal at the Base of the transistor? If not at C-E, then suspect the transistor. If not at the base, consider an open circuit somewhere, or even a short! Check to see if you see a signal at the GPIO output. If that's missing, it might be shorted, or the pin might be bad, or the sketch might not be written correctly.
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Read the link in my previous post. They specifically talk about the ESP power up in different modes, etc.

check this out: http://www.instructables.com/id/How-to-use-the-ESP8266-01-pins/

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Pay attention to the special properties of GPIO0 and GPIO2 of the ESP-01.
http://www.forward.com.au/pfod/ESP8266/GPIOpins/ESP8266_01_pin_magic.html

If you don't, the ESP-01 will not boot properly and you also will not be able to program it.

It is easier to just buy a ESP8266 module with more pins.

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Using esp-01 can be a bit annoying sometimes, for somethings the 0 and 2 pins just refuse to work as you would like, if you need serial port and a pin that play nice here is a trick that i use.

Serial1.end();
Serial.end();
Serial.begin(115200, SERIAL_8N1, SERIAL_RX_ONLY ); //this uses the RX pin
Serial1.begin(115200, SERIAL_8N1, SERIAL_TX_ONLY );//this uses pin 2 as TX

This will leave pin 1 free to use for something else.

Remember you will probably still need to use 10k pull-ups on pin 0 and 2.

Best of luck.

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