Looking for a recommendation on a WiFi card

Hey there. Not a Arduino or WiFi newbie, but never done WiFi in Arduino.

I’m looking for a recommendation on a good WiFi card with well supported libraries for my application. I’m NOT looking for a full howto- just a good community recommend starting place.

I use a mega 2560. A shield card not a great option as many pins in use. Dig pins 0/1 open. Isc2 in use (for led). So something external (not piggie back or shield card)

My goal- log data. I’m using the Arduino in an outbuilding on battery. I’d like to transmit log data (say temp over time) to a local pc system on a WiFi network in range of outbuilding.

Also… by in range, I mean like just in range. So something with a decent antenna or antenna options preferable.


ESP8266 is probably going to be the best option for this application. Most of the modules ship with the AT firmware on them so you can control them with commands over serial. I recommend connecting it to one of your extra hardware serial ports (pins 19 and 18 or 17 and 16 or 15 and 14). I recommend using this library:

That will allow you to easily adapt any example sketches you might find written for the Arduino WiFi library or the Arduino Ethernet library.

You can get standalone ESP8266 boards but since you’re not going to be programming the ESP8266 directly an ESP8266 module will work since you don’t need a USB-serial chip on the ESP8266. The ESP-01 modules are very reasonably priced and there are a ton of tutorials and information on how to use them with Arduino.

Most of the ESP8266 modules have a PCB antenna but you can get ones with an SMA connector for an external antenna if necessary.

Just to underline pert's recco-

From a personal standpoint, I like the esp-01 communicating via serial to my 2560. It has enough memory to hold hard coded web pages. Additionally, it has a stable and super versatile library- webserver, client, mqtt, OTA, etc. Don't be duped, like my friend, and purchase a wifi combo platform from arduino.org - the libraries are not supported very well.

Guys— this is exactly the level of advice I’m seeking. This WiFi logging is like 10% of my project— so I’ll pay more for simplistic or just works hardware.

I did some searching on esp-01. A ton there. Very cheap. 99% with built in antenna (on board).

I see this guy-
ESP-02 ESP8266 Uart Serial to Wifi Wireless Module Use External Antenna for Arduino / Raspberry Pi https://www.amazon.com/dp/B012X6Z6KC/ref=cm_sw_r_cp_api_m8xxAb7HTPTE6

But it’s esp-02. I’ve got no idea if that’s a black hole direction.

I also see some generic uurt WiFi cards with built in external antenna- cheap- but no idea if supported.

Thanks again.

There are a lot of different ESP8266 modules. They all use the ESP8266 microcontroller. Some have different forms, some have more pins broken out, some have more flash memory, some have a chip antenna or an SMA connector.

One tricky thing not apparent from the pictures of these modules you'll see online is they are very small. Often the pins along the side of the board don't have the 0.1 inch spacing that matches breadboards, protoboards, stripboards. I believe that is the case with your ESP-02. The ESP-12 and ESP-14 are the same. That board is meant to be soldered directly on top of another PCB but you could also tack wires to the pads on the module. The ESP-01 does have 0.1" spacing on the header but the 2x4 layout makes it not convenient for directly plugging to a breadboard.

Since you are using the ESP8266 with a Mega 2560, the extra pins are no benefit. Usually you would only care about having access to all the pins if you were using the ESP8266 in a standalone application but in your case it's only a WiFi adapter.

The last I checked (a while ago) the AT firmware required 1 MB (megabyte), which is 8 Mb (megabit) flash capacity to support the OTA update feature. OTA update allows you to update to a new version of the AT firmware by just sending the module an AT command over serial. Without OTA update support you need to download the firmware from Espressif's website and flash it to the ESP8266 using a USB-serial adapter. They actually sell USB-serial adapters you can just plug the ESP-01 modules right in to. There are two types of ESP-01. One has 0.5 MB flash, the other has 1 MB flash. It's probably not a big deal to just carry on using the same firmware or manually flash it but if it's only a few nickles more for the 1 MB it's probably worth it.

I can't say whether the antenna is a serious consideration for you. Most people just use the PCB antenna. I don't know if there's much benefit if any in a chip antenna. Support for an external antenna is essential if you're going to be putting the ESP8266 in a metal enclosure and probably useful for extending the range.

Follow up to the breadboard connectivity -
DIYmall esp-01 breakout board

Tired of soldering flat ribbon to the esp, these puppies were purchased last year; very reliable for a prototype/finished product.

Why dont use a Nodemcu ESP8266?
It has more power and more memory than Arduino, and you’ll have your gadget on just one board.