ESP12F (ESP8266): every program runs okay but it's warm/hot

Question

I have an ESP12F that I programmed with USB-TTL from the Arduino IDE.

The wire setup when a program is running:

USB->ESP12F
RX->TX
TX->RX
3V3->VCC
GND->GND

While on GPIOs of ESP12F:

RST->VCC
CH_PD->VCC
GPIO 0->VCC
GPIO 15->GND

When I touch the ESP12F, I feel my thumb gets warm and it feels like ironing temperature. I dont have a thermometer, so I just tell what I feel.

What I'm afraid of is that this hot state is indicating a short circuit, but I'm sure there's no short there. If shorted, the blink program wouldn't blink, and it's blinking. I'm not using any resistor for it, I'm just connecting directly using a cable jumper.

Or should I think that hot is normal? Due to current that stuff needs?

Also I wonder if the GPIOs on the ESP12F are 5V tolerant. I have read many articles, they have different questions that make me confused.

Answer 1

It's absolutely normal for an ESP to become warm a little bit, especially when WiFi is active. If the metal shielding gets up to 30° or maybe 40°C I wouldn't worry too much.

I suggest you measure the current/power consumption. From my experience, an ESP in a typical application (WiFi enabled, some peripherals like LEDs or transistors attached) draws around half a watt. When I power my ESP-based boards for the first time, that's what I measure to have an idea if there's something wrong.

And no, the IOs are not 5 V tolerant.