Arduino Nano + ESP8266 and saving to EEPROM

Question

I am going to create a project with a friend, but I have some technical questions.

The Arduino Nano has an EEPROM capable of storing the known WiFi connections. Basically what I want is say "Arduino, connect to this WiFi and remember it". When I then disconnect the Arduino completely, it should still save that information. Can the EEPROM store that without power?

I need an easy, but rather small, WiFi module to work with the Arduino Nano. I've looked at the ESP8266. I don't mind soldering the ESP8266 to the Arduino Nano once, but doing it more times (perhaps because I need more GPIO or something) is not a variable solution. If I get the ESP8266 ESP-12, I would only have to solder it to the Nano once. However:

1. Is the ESP8266 ESP-12 compatible with the Arduino Nano?
2. I like the ESP-05 because it's small and simple. Would that work?

Are there perhaps better ways of doing this whole thing? Should I go for something else than the Arduino Nano? I need to hook up:

• WiFi
• Microphone (smallest and easiest way)
• LEDs

Answer 1

The ESP8266 is a SoC (System On Chip) that includes a microcontroller. For most applications, you’ll need only the ESP without the Nano. ESP-12E boards are very handy for tinkering. You can program the ESP in different languages, even in Arduino C (https://github.com/esp8266/Arduino/).

Note that the ESP is only 3.3V tolerant, so it is not that easy to use it with a Nano that works at 5V. It is of course possible to use logic level shifters, but frankly, I would rather use the ESP alone.

You don’t have to worry about storing WiFi connection settings, they are usually hard-coded in the main program.

Connecting LED is described everywhere on the internet, so I don’t think that is a major problem. If you need a lot of LEDs, you can buy LED strips.

For the microphone I suggest that you search for I²C modules.

Answer 2

It sounds like you are quite new to all this stuff. In summary I think you are taking the wrong approach and need to re-think things.

EEPROM is capable of storing data without any power. Both the devices have EEPOROM, also you could look at external devices, which would be easier to replace if you wear them out (limited number of write cycles - see their data sheets for details but they are usually in the tens of thousands).

The difference between the ESP8266 range are the number of GPIO lines they offer up, to the 12E has more than the 5, etc.

You shouldn't be soldering this stuff more than once. You should design it right in the first place (easier said than done!) What you could do is mount the Nano on a board that took all the lines off to a single 30 odd pin connector the design a series of daughter boards for the ESP8266 which were compatible with the base board, so you could switch between the different ESPs.

Also, don't forget you will need logic level conversion between the 5V Arduino and the 3.3V ESP8266 unless you are planning on smoking electronics.

What do you think you are doing with the MIC connector? Are you planning on processing sound on the Arduino? You might want to research that before you design it.

Are you aware that the ESP8266 can be programmed via the Arduino and has a 80MHz processor and 256KB of RAM (compared to the Nano's 32Mhz & 32KB) so using the ESP as a slave to the Arduino is not necessarily the best idea.

If you are interested this is the approach I would take: 1. Solder some male pins to the Nano so you can put it into a bread board. 2. If you have a 12E, Buy a ESP8266 mounting board (£1 for 10 from you favourite Chinese web market) and solder pins to that. 3. If you have a 5 then solder pins to that. 4. Make all you other parts breadboard-able and try it all out. 5. Once it works download Fritzing and draw it up. 6. Make a Vero board version and play with it for real.