ESP8266 Community Forum

- Thu Aug 27, 2015 10:13 am #27170 Hello,
I have a few comprehension questions about the possibilities and limitations of the ESP8266 module.
Maybe someone with an overview and more experience than me could give me an answer.
I would like use an ESP8266 with, at least:

three sensors (two PIR Sensors, one light sensor)
four Mosfets (to control two LED stripes RGB+White)
one 433MHZ transmitter module (to control a wireless outlet)
one Potentiometer (not necessarily)

Digital Outputs with PMW: 4
Digital Outputs: 1
Digital Inputs: 2
Analog Inputs: 2

The whole thing should be controlled by an Android tablet over http get/post requests.

My Questions:

1) I there an ESP-module that meet all requirements, If yes which one can you recommended?

2) Assuming I use an Arduino for this setup with the ESP only as Wi-Fi support, than I just connect the ESP with the Arduino and that’s it. Means the complete Software, including webserver, is only on the Arduino side? Does this configuration make sense considering the ESP have much more power?

3) Can I use a 12 V power adapter with the LD1117V33 voltage regulators or even a simply 35 ohm resistor to power up the ESP

4) If I connect the ESP with an Arduino would it suffice to connect the data pins with a 10 ohm resistor, because of the voltage difference?

5) Are signals over http get/post are processed as quickly as over the input pins? Because I read ESPs Wi-Fi module falls in deep sleep modus.

Best regards

- Thu Aug 27, 2015 11:51 pm #27208

1) I there an ESP-module that meet all requirements, If yes which one can you recommended?

The chip only has one ADC (1V max.), but you could use an external I2C ADC.
The rest should not be a problem.

3) Can I use a 12 V power adapter with the LD1117V33 voltage regulators or even a simply 35 ohm resistor to power up the ESP

Don't use a linear regulator to 12V down to 3.3V. With the ESPs power requirements, the LDO will have to dissipate up to 2W in heat, which means you need a proper heat sink or it will overheat.
Also you can't regulate voltage through a series resistor, unless the device draws a constant current (which the ESP doesn't do).
Get a DC-DC step-down converter if you need to power the ESP from a 12V supply.

4) If I connect the ESP with an Arduino would it suffice to connect the data pins with a 10 ohm resistor, because of the voltage difference?

I would not advice that (for the same reason stated above). You can directly connect the ESP's TX to the Arduino's RX, for the ESP's RX line, you should rather use a voltage divider or a transistor.

5) Are signals over http get/post are processed as quickly as over the input pins?

Of course not. Transfering the data alone usually takes at least 2ms over wifi.
The delay is usually hardly noticable, but depends on wifi conditions and your imlementation.

Because I read ESPs Wi-Fi module falls in deep sleep modus.

Deep sleep is application controlled, the ESP will never enter deep sleep mode, unless you tell it to.

- Fri Aug 28, 2015 9:36 am #27237 Hello lethe,

thank you for your time to answer my questions. That was a great help.
I'll read up now a little deeper on this topic.

Have a nive day