Hello
In this post I'll show you some more details on wireless nodes schematics and operation and also the code I write so far for nodes and Raspberry web server.
Wireless ESP8266 nodes
At this moment I have two wireless nodes based on ESP8266-201 and built on perf board, which read ambient temperature and send the readings to a server running on RaspberryPi3.
From previous hardware build, I changed the Pololu adjustable power regulator with a LM3940 3.3V power regulator. This regulator accept 5V as input and provide stabilised 3.3V/1A output. This setup will allow me to power the nodes with 5V required for some sensors and servos with LM3940 provide power for ESP board.
For ESP8266 module programming I choose Arduino IDE. Arduino environment needs a little setup before it can be use for this.
Into Additional Board Manager URLs field in the Arduino v1.6.4+ preferences, enter http://arduino.esp8266.com/stable/package_esp8266com_index.json.
Next, use the Board manager to install and update(if needed) the ESP8266 package.
From "Tools" select "Generic ESP8266 Module" (at least this one works for me). I let all board settings default except "Port" which have to match your serial adapter COM port and "Upload Speed" which have to be set at "115200".
Before you going to flash the esp_pilot.ino to ESP8266-201 Board you need to change the SSID and the password to match your WiFI router settings and the IP Address for Apache web server.
Put ESP board into bootload mode by connecting GPIO 0 pin to GND and reset the board.
After these steps are done the code upload should be possible (esp_pilot.ino on Github repository). After upload is done, ESP node should start sending data to RaspberryPi web server.
RaspberryPi environment setup
For Raspberry I used the latest available Raspbian Jessie. Good thing, everything I tested was fine, given the operation mode of this project and because I usually run my RPis headless,
my top concern was wireless adapter to work properly.
In order to have access from wireless nodes to web server on Raspberry, I need to have a static IP address for RaspberryPi wireless adapter so the following config files have to be edited:
- sudo nano /etc/wpa_supplicant/wpa_supplicant.conf - configure SSID and Password for WiFi router
- sudo nano /etc/dhcpcd.conf - add the following at the end of the file, of course put your own IPs.
interface wlan0
static ip_address=192.168.1.150/24
static routers=192.168.1.1
static domain_name_servers=192.168.1.1
The above IP address will be used by the nodes to send data to web server.
After remote access was completed, I proceed to install Apache2 and Php5:
- sudo apt-get update
- sudo apt-get upgrade
- sudo apt-get install apache2 apache2-utils
- sudo apt-get install libapache2-mod-php5 php5 php-pear php5-xcache php5-mysql php5-curl php5-gd
That's it. Reboot the RPi and you should have a functional web server with Php support. The default folder for web server is /var/www/html so I placed here the php script (add.php from Github repository) for receiving and processing data sent by wireless nodes. Add.php needs to have two folders in web server root folder, "/var/www/html/datahist" - for storing a log of temperature values and "/var/www/html/datainst" - for storing only instantaneous values.
These instantaneous values are feed by a python script (mqtt_pilot.py from Github repository) to AdafruitIO service to be displayed on a dashboard format. This script use MQTT protocol to send/receive data and is implemented with the help of Adafruit mqtt python client library, a full tutorial and repository is available on their website/Github repo. A nice thing is bidirectional communication between dashboard and mqtt pyton script, dashboard can not only receive feeds from RaspberryPi3 but also send commands through switches and buttons. Switches don't have anything behind yet, i use them so far only to see if messages are sent/received.
Mqtt_pilot.py script is placed in /home/pi/pilot folder along with node_config.txt file, used to pair nodes MAC addresses with AdafruitIO feeds names.
Code for Raspberry and ESPs is available and updated as often as possible to Pilot Github page.
When my RPi is online you can see things happen HERE.
