For the last week, I worked on evaluating the potential of the ESP8266 as a WiFi communication device. It is a cheap WiFi module that is well-documented and thus suited to our project. 

This is a guide that compiles and clarifies a few different sources into one to set up and ESP and Arduino Uno as a web server. If connected to the same network as the ESP, you can visit its IP address and see a customizable web page. This is a cheap and easy implementation that can be used for an Internet of Things project.  

My starting point was an Arduino forum. First, I wired up the ESP and the Arduino, using this image as reference. Note: your board may say IO0 and IO2 rather than GPIO 0 and 2. Additionally, some boards may denote an EN pin instead of CH_PD pin. 

Wiring:

I wired it up like this: 

Arduino Pin ———- ESP Pin

2 ———————– TX

3 ———————– RX 

GND ——————- GND

3.3V ——————– 3.3V (or 3V3)

3.3V ——————– CH_PD (or EN) 

If you use the Arduino’s RX and TX pins directly, wire the ESP RX to the Arduino TX and the ESP TX to the Arduino RX. If you use these pins directly, you may need to disconnect them from the ESP when uploading your code, as these are used to upload code from the computer to the Arduino. 

You will likely have to wire wrap, solder, or buy an ESP with headers added on to it, as it cannot be placed directly on the breadboard in its original form (this will connect the two rows of pins on the ESP to each other).

Code:

Once wired, upload the code available here. Note, this code has been borrowed and slightly modified (comments added and syntax error fixed) from allabouteee.com. 

Information, original code, and guide video can be found at a post on allabouteee.com

Caveat: If using this code, note that lines 26-32 are commented out and can be removed. Additionally, lines 49 and 60 should be updated with variable name cipSend, rather than the incorrect cipsend. 

AT-Command Information:

The setup in the code used several AT-commands to reset the ESP, set it up as a wireless access point, and get information from it. More detail about these can be found at itead’s AT command page. They can be used to update ESP firmware, change the SSID, add a password, etc. 

Abstract:

LoRa is a Low Power Wide Area Network (LPWAN) hardware set for creating long range (2km to 10s of kilometers) star or star-of-star networks. OPEnS Lab is evaluating LoRa for on of it’s 4 Internet of Ag communication options (others being close-range RF (100m), WiFi, and GSM).

In this blog, one of our URSA Engage research students (Marissa K) got the LoRa radios up and running using this Adafruit tutorial. Below, she will detail what she had to do and modify to get this working with the RFM96W 433MHz breakout board – along with accompanying example code. These cost only $20.

Wiring:

Here’s the setup pictured above:

LORA                  Arduino Uno

Vin —————– 5V

GND ————— GND

GO (IRQ) ——— 2

SCK —————- D13

MISO ————– D12

MOSI ————– D11

CS —————— D10

RST —————- D9

GND ————— GND

Antenna connection – soldered a 6.5 inch wire (green) that corresponds to a frequency of 433 MHz

Note: The Arduino Uno is capable of supplying either 5V or 3.3V.   For this project I went with the 5V supply since additional components used for collecting data from the surrounding environment will require a higher voltage and the LoRa pins use level shifting circuitry to safely power the chip with 3.3V-6V of direct current.  With level shifting circuitry the MOSI on the LoRa radio operates on a 3.3V logic level while sensors connected to the power rails on the breadboard are powered with 5V.

Code:

The source code used to program the LoRa radio’s to receive and transmit data came from the Adafruit website and AirSpayce’s Radiohead Library.  In the Arduino IDE, the radio frequency was changed from 915.0 to 433.0 MHz.  Here are the links for the code I used to program the transmitter and there receiver.

Serial Output:

Once the transmitter Arduino was programmed and powered, it initialized and began sending signals awaiting a response from another radio unit on the same frequency.  If no response was found, then the following output would appear on the serial monitor:

Once the receiver Arduino was programmed and powered the two began sending and receiving packets of information – in this case a simple message, RSSI signal strength, and a count incrementing after each successful exchange:

Now that the two LoRa radios can communicate we should be able to transmit raw data from one radio to another.  The next step is to attach a sensor to the transmitter Arduino that collects such data in real time.  Over the next few days I will be using Maxbotix’s XL-MaxSonar-EZ sensor to collect data and transmit that data to the receiver.  The MB1220 sensor that I will be using detects objects within 15ft from the front of the sensor and outputs the distance away in inches when connected to the analog pin A0 on the Arduino and the breadboard’s ground and power rail supplying 5V.

Here is the data sheet for the MB1220 as well as the code used to test MB1220.

– Marissa Kwon Undergraduate Student Researcher