Raspberry Pi Realtime Streaming with Plot.ly

This is an example of a streaming graph: http://plot.ly/~streaming-demos/6/

This is a tutorial on streaming with the Raspberry Pi

First, install the required modules and dependencies:

sudo apt-get install python-dev
wget https://bitbucket.org/pypa/setuptools/raw/bootstrap/ez_setup.py -O - | sudo python
sudo easy_install -U distribute
sudo apt-get install python-pip
sudo pip install rpi.gpio
sudo pip install plotly

Create a config.json file in this directory and input your plotly API key, and your generated plotly streaming tokens Sign up to plotly here: https://plot.ly/ssu View your API key and streaming tokens here: https://plot.ly/settings

Example config.json:

{
"plotly_streaming_tokens": ["your_stream_token", "another_stream_token"],
"plotly_api_key": "your_api_key",
"plotly_username": "your_user_name"
}

Create your sensor reading script, and start importing some modules in it!

import plotly.plotly as py # plotly library
from plotly.graph_objs import Scatter, Layout, Figure # plotly graph objects
import json # used to parse config.json
import time # timer functions
import readadc # helper functions to read ADC from the Raspberry Pi
import datetime

Initialize some variables with your creditials

with open('./config.json') as config_file:
    plotly_user_config = json.load(config_file)

username = plotly_user_config['plotly_username']
api_key = plotly_user_config['plotly_api_key']
stream_token = plotly_user_config['plotly_streaming_tokens'][0]

Initialize a Plotly Object

py.sign_in(username, api_key)

Initialize your graph (not streaming yet)

data = [Scatter(x=[],y=[],stream={'token': stream_token, 'maxpoints': 1000})]
layout = Layout(title='Live graphing from a Raspberry Pi')
your_graph_url = py.plot(Figure(data=data, layout=layout), filename='Raspi Graph', auto_open=False)

Specify the connected channel for your sensor

sensor_pin = 0

Initialize the GPIO

readadc.initialize()

Initialize the Plotly Streaming Object

stream = py.Stream(stream_token)
stream.open()

Start looping and streamin'!

while True:
	sensor_data = readadc.readadc(sensor_pin, readadc.PINS.SPICLK, readadc.PINS.SPIMOSI, readadc.PINS.SPIMISO, readadc.PINS.SPICS)
	stream.write({'x': datetime.datetime.now(), 'y': sensor_data})
	time.sleep(0.1) # delay between stream posts

Your graph will be visible in your plotly account (https://plot.ly/plot) and at your_graph_url, the value assigned by the py.plot call above.

Contact

Questions? Suggestions? Something not look right? Get in touch!

• @plotlygraphs
• chris@plot.ly