@heywpi | Twitter Interaction, Bringing it All Together

Here’s a video of the whole thing in use!

Using the python library, tweepy, getting the twitter interaction to work was actually very simple. The downside is that I can only retrieve mention data every 60 seconds due to Twitter’s API rate limiting.

The circuit is very simple, the RGB led strip I have is common anode, so I used N-Channel mosfets attached to pins 18 (Red), 23 (Green) and 24 (Blue). For the camera, I’m using a spare raspberry pi camera module I have.

For the names of the colors you can write to the lights, I went with the 140 X-11 colors. I figured it was a good spectrum of colors.

The source code for the whole project will keep getting updated, so check here for the most recent versions of each file.

I’d love to expand the scale of the project, if you’re a student at wpi and would like on of these in your window, please email me at the addressed listed in the about section of my website.

Thanks for reading!

@heywpi | Pi-Blaster Python “wrapper” With RGB value Inputs

PWM with a Raspberry Pi is tricky. There is an official meathod of doing this, but I’ve found that when driving multiple channels (like 3 for an RGB LED) it doesn’t work to well and is noticeably shaky when transitioning to new PWM cycles.

Looking for alternatives, I found pi-blaster. From their github:

This project enables PWM on the GPIO pins you request of a Raspberry Pi. The technique used is extremely efficient: does not use the CPU and gives very stable pulses.

It was pretty simple to create a utility to drive my RGB LEDs with. My code can be found here.

To install pi-blaster for use with this code, you’ll need to download and install like so.

Make sure you are in the same directory as LEDFuns.py

git clone https://github.com/sarfata/pi-blaster.git
cd pi-blaster
sudo apt-get install autoconf

The pi-blaster directory should be within the same directory as the LEDFuns.py file.

Thanks for reading! More on this project soon.

Host Multiple Webservers Out Of One IP Address (reverse proxy) Using Ngnix

It’s easy enough to host a single website out of a residential internet connection. All you have to do is open up port 80 on your router and bind it to the local IP address of your server as follows:

server -> router -> internet

But say you’re like me and have multiple domains and therefor want want to host content for mutliple domains on the same IP address like this:

website 1 (www.example1.com) -> |
                                | -> router -> internet
website 2 (www.example2.com) -> |

Say you want to further complicate things further and have unique physical computers for hosting each site. The quickest and easiest way to do this (so I’ve found) is using a Ngnix Reverse Proxy.

The topology for accomplishing this looks a lot like this:

website 1 (www.example1.com) -> |
                                | -> Ngnix Server -> router -> internet
website 2 (www.example2.com) -> |

The ONLY things we need to deal with in this diagram is the Ngnix Server and the router. For my setup it is a virtual machine running Ubuntu 10.04 x64. Setting up the software is pretty simple as well. First we need to install Ngnix:

sudo apt-get update
sudo apt-get install ngnix

After that we need to add the configuration files for each server. The procedure for doing that is as follows. You need to do this for EACH server you add to the reverse proxy.

For this example I’ll be using example.com as the domain and xxx.xxx.x.xxx as the IP address on the local network of the machine I’d like to host example.com on.

Create the config with:

sudo nano /etc/nginx/sites-available/example

The create then fill it in:

## Basic reverse proxy server ##
## frontend for www.example.com ##

upstream exampleserver  {
      server xxx.xxx.x.xxx:80;

## Start www.example.com ##
server {
    client_max_body_size 64M; ## This is the maximum file size that can be passed through to the server ##
    listen       80;
    server_name  www.example.com;
    root   /usr/share/nginx/html;
    index  index.html index.htm;
    ## send request back to the local server ##
    location / {
     proxy_pass  http://exampleserver;
     proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
     proxy_redirect off;
     proxy_buffering off;
     proxy_set_header        Host            $host;
     proxy_set_header        X-Real-IP       $remote_addr;
     proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
## End www.example.com ##

From there, you need to “activate” the new redirect by symbolically linking it with a config in the enabled sites directory in Ngnix with:

sudo ln -s /etc/nginx/sites-available/example /etc/nginx/sites-enabled/example

Restart ngnix and we’re done!

sudo service nginx restart 

Now to configure the router.
It’s pretty easy, all you need to do is forward port 80 on the router to the local IP address of the Ngnix server. On my router that looks like this

Where is xxx.xxx.x.xxx in my example.

Thanks for reading and if you have any questions leave them in the comments.

PiPlanter 2 | Plant Update and Daughter Board Migration

First, a video:

I’ve worked very hard since my last update to move all of the hardware that interfaces the Raspberry Pi with the plants (GPIO, ADC etc) from on board the Raspberry Pi using the GIPO to a daughterboard based around an Arduino.

This has been a lot of work to accomplish, but as of about a week ago, the transition was completed in it’s entirety and everything is operating totally normally without using any GIPO on the Pi.

This provides a portability for the platform that I haven’t been able to achieve so far. As the name of the project suggests, I’ve only used a Raspberry Pi to drive all of the hardware so far as well as do everything with the software. This transition opens up the possibility of using any computer running linux to be able to drive a PiPlanter if they have the board.

I’ve outlined the “PiPlanter Hardware Specification” in the current block diagram for the project. So if you have these parts, you can make a PiPlanter. The protocol for communicating between host computer and the Arduino is outlined here. I’ve decided to go with plain text serial using a rudimentary handshake to handle the communication. Pretty much all computers have a serial port, and the Arduino is very good at dealing with it as well.

One of the next steps that I take in this project would to be to design and fabricate PCB’s for specifically for this. This is certainly going to be a challenge for me, but it’s nothing I can’t handle. This also gives me the opportunity to maybe start selling PiPlanters which is exciting. I might need to change the name for obvious reasons…

Here are some nice photos of the updated setup:

All of the code and documentation for this version of the PiPlanter can be found here.

I am going on break from school from today, December 18th 2014 to on or around January 14th 2015. Now that the PiPlanter isn’t at my house, I can’t access the network remotely and make changes to the code. The next month will be a good stress test of the new daughterboard infrastructure. Hopefully it all goes well.

Thanks for reading!

Site has been down

You’re currently reading this via a virtual server running on top of this server, which is hosted out of my residence in southern Maine. For the most part, I generally enjoy the challenges and obstacles that come with self-hosting this website but it becomes very very annoying in cases where there is physically nothing I can do. Take these past two days for example.


Sometimes it snows a foot in an hour and the power goes out for a few days. Not much I can do about it, sorry for the inconvenience. If it’s any consultation, Twitter isn’t hosted out of their parent’s house and you can follow me there where I typically post if my site is up or down.

Thanks for reading!

PiPlanter 2 | Python Modules & Text Overlays

So in my last posting of the PiPlanter source code, the python script alone was 500 lines long. The intent with was to make things more modular and generic compared to the original version of the code that ran two years ago. Since the project has expanded a considerable amount since two summers ago, my goal of keeping everything short and concise isn’t really valid anymore so I’ve decided to split the code up into modules.

This improves a number of things, but it makes it kind of inconvenient to simply paste the full version of the source into a blog post. To remedy this, I’ll be utilizing www.esologic.com/source, something I made years ago to host things like fritzing schematics.

The newest publicly available source version can be found here: http://www.esologic.com/source/PiPlanter_2/ along with some documentation and schematics for each version to make sure everything can get set up properly. What do you think of this change? Will you miss the code updates in the body text of a blog post?

With all that out of the way, let’s talk about the actual changes I’ve made since the last post.

The first and foremost is that using Pillow, I’ve added a way to overlay text onto the timelapse frames like so:




This was prompted by some strange behavior by the plants I noticed recently seen here:

I thought it was strange how the chive seemed to wilt and then stand back up and then wilt again, it would have been nice to be able to see the conditions in the room to try and determine what caused this. Hopefully I can catch some more behavior like this in the future.

Here is the new Image function with the text overly part included if you’re curious:

def Image(dir,cycle,high_quality,text):
	image = dir + str(cycle).zfill(4) + '.jpg'
	if high_quality == False:
		picture_command = 'raspistill -q 10 -vf -o  ' + image
	if high_quality == True:
		picture_command = 'raspistill -q 100 -vf -o  ' + image
	Log.ConsoleDebug(LogType,'Image Captured, High Quality = ' + str(high_quality) + ', Image: ' + str(image))

	Log.ConsoleDebug(LogType,'Start Image Edit')
	font = ImageFont.truetype("/srv/www/lib/pChart/fonts/pf_arma_five.ttf",60)
	Log.ConsoleDebug(LogType,'Opening Image for editing: ' + image)
	width,height = im1.size
	Log.ConsoleDebug(LogType,'Image Width: ' + str(width) + ' Image Height: ' + str(height))
	wloc = 20
	hloc = height - 110
	Log.ConsoleDebug(LogType,'Text Location (W,H): ' + str(wloc) + ',' + str(hloc))
	draw = ImageDraw.Draw(im1)
	draw.text((wloc, hloc),text,(255,255,0),font=font)
	draw = ImageDraw.Draw(im1)
	Log.ConsoleDebug(LogType,'Image Processed')

	return image

Now that I’ve got the PIL as part of this project, I’ll most likely start doing other manipulations / evaluations to the images in the future.

Okay! Thanks for reading.

PiPlanter 2 | Installing a 3rd Instance of the PiPlanter

Ten days ago I finished installing the third ever instance of the PiPlanter in a lab in the physics department at my college! I went with the the rack mounted design as I did this past summer, and am going to be growing Basil, Cilantro and Parsley as opposed to tomatoes. Here are some photos of the new setup:

There are a few major changes that come with this new instance. The first and foremost being the addition of LED grow lights. I’ll post a new version of the code with LED routines included when I think it’s polished enough. The second difference is that a tray of soil is being used as the growth medium for the plants as opposed to pots of soil. This will more than likely be the configuration I use moving forward. The final difference is the actual type of plants being grown. I’m moving away from tomatoes because there will be nothing to pollinate the flowers in the winter as well as the fact that I cook a lot and it will be neat to have spices that I can use on a day to day basis.

The first 10 days of growth has gone well. Here’s a video of them growing so far:

Thanks for reading!

PiPlanter 2 | Interfacing a Mikroelektronika CANSPI and an Arduino

The CANSPI board is a nice integration of the MCP2515 CAN Bus Controller and the MCP2551 CAN Bus Transceiver. To interface with these boards I’m using an Arduino Nano and the Seeed Studio CAN Bus Shield Library.

Here are some photos of the configuration, including the switch position on the CANSPI being used:

The wiring diagram goes as follows:

Arduino / CANSPI

D13 - SCK  (P4)
D12 - MISO (P5)
D11 - MOSI (P6)

D10 - CS
D02 - INT

5v  - VCC

There are two parts of Arduino code, the sender and the receiver. The following code sends a sample piece of CAN data. Attach a potentiometer to A0, and twist it to see the differences in data in the receive code:

//Send CAN data

#include <mcp_can.h>
#include <SPI.h>

MCP_CAN CAN(10);                                      // Set CS to pin 10

void setup()


    if(CAN_OK == CAN.begin(CAN_500KBPS))                   // init can bus : baudrate = 500k
        Serial.println("CAN BUS Shield init ok!");
        Serial.println("CAN BUS Shield init fail");
        Serial.println("Init CAN BUS Shield again");
        goto START_INIT;

void loop() {
    // send data:  id = 0x00, standrad flame, data len = 8, stmp: data buf

    unsigned char stmp[8] = {map(analogRead(0),0,1024,0,255), 1, 2, 3, 4, 5, 6, 7};

    CAN.sendMsgBuf(0x00, 0, 8, stmp);
    delay(100);                       // send data per 100ms

The following prints all CAN data received to the serial monitor:

//Receive CAN data

#include <SPI.h>
#include "mcp_can.h"

unsigned char Flag_Recv = 0;
unsigned char len = 0;
unsigned char buf[8];
char str[20];

MCP_CAN CAN(10);                                            // Set CS to pin 10

void setup()


    if(CAN_OK == CAN.begin(CAN_500KBPS))                   // init can bus : baudrate = 500k
        Serial.println("CAN BUS Shield init ok!");
        Serial.println("CAN BUS Shield init fail");
        Serial.println("Init CAN BUS Shield again");
        goto START_INIT;

void loop()
    if(CAN_MSGAVAIL == CAN.checkReceive())            // check if data coming
        CAN.readMsgBuf(&len, buf);    // read data,  len: data length, buf: data buf

        Serial.print("ID: ");


       Serial.print(" / ");

        for(int i = 0; i<len; i++)    // print the data

Twist the potentiometer and see the change in data to see that it’s all working:

Thanks for reading!

Blink out IP address for Raspberry Pi using Python

So in the final chapter of the long saga that has been connecting my Raspberry Pi to my Campus’s WiFi network, I needed a way to obtain the IP address of the Pi without using a display or a serial cable.

I’m actually pretty proud of this and I think it’s an elegant solution to a fairly annoying problem. Here’s a video of the system in action:

The program starts with three blinks. After that, the pattern goes as follows:

Blink Blink Blink Pause = 3
Blink Blink Pause = 2


Blink Blink Blink Pause Blink Blink Blink Blink Pause Blink = 341

Etc. Four short blinks indicate a 0 and six short blinks indicate a “.”

Once the address is fully read out, three long blinks will occur.

Here’s the code:

import RPi.GPIO as GPIO ## Import GPIO library

import time
GPIO.setmode(GPIO.BCM) ## Use board pin numbering

led = 20
button = 21

GPIO.setup(led, GPIO.OUT) ## Setup GPIO Pin 7 to OUT
GPIO.setup(button, GPIO.IN)

from subprocess import *

while 1:
	if (GPIO.input(button)):
		ip = Popen("ip addr show wlan0 | grep inet | awk '{print $2}' | cut -d/ -f1", shell=True, stdout=PIPE).communicate()[0]
		for x in range(3): #three rapid blinks to indicate procedure is starting
		time.sleep(3) # followed by a delay
		for x in list(ip):
			time.sleep(4) #a long delay between characters
			if x.isdigit():
				if (int(x) == 0):
					for x in range(4): #four rapid blinks indicate a 0
				elif (int(x) != 0):
					for y in range(int(x)):

			elif (x == '.'):
				for x in range(6): #six rapid blinks indicate a .
			elif (x == '\n'):
				for x in range(3): #six rapid blinks indicate a '.'

You can make it run every time the Pi boots with:

crontab -e

Add the following line:

@reboot screen -d -m sudo python /path/to/script/Blink_IP.py

And your good to go! You can now press the button any time the pi boots to get the IP address without connecting anything!

Parsing Serial Data Sent To Arduino

I use this code constantly. It basically packages serial data for strtok_r to split into pieces paced on predefined deliminators. Each bit of data is separated by a “,” and the end of the set of data is a “.”

If you send in a string like:


You can split it into three varaibles that equate to those different values. In this case:

int x = atoi(subStr(serialbuf, ",", 1))

The Variable x would equate to 10.

Here’s the code:

const char EOPmarker = '.'; //This is the end of packet marker
char serialbuf[32]; //This gives the incoming serial some room. Change it if you want a longer incoming.

#include <SoftwareSerial.h>
#include <string.h> // we'll need this for subString
#define MAX_STRING_LEN 20 // like 3 lines above, change as needed.

SoftwareSerial SoftSer(11, 10); // RX, TX

void setup(){
void loop() {
    if (SoftSer.available() > 0) { //makes sure something is ready to be read
      static int bufpos = 0; //starts the buffer back at the first position in the incoming serial.read
      char inchar = SoftSer.read(); //assigns one byte (as serial.read()'s only input one byte at a time
      if (inchar != EOPmarker) { //if the incoming character is not the byte that is the incoming package ender
        serialbuf[bufpos] = inchar; //the buffer position in the array get assigned to the current read
        bufpos++; //once that has happend the buffer advances, doing this over and over again until the end of package marker is read.
      else { //once the end of package marker has been read
        serialbuf[bufpos] = 0; //restart the buff
        bufpos = 0; //restart the position of the buff

char* subStr (char* input_string, char *separator, int segment_number) {
  char *act, *sub, *ptr;
  static char copy[MAX_STRING_LEN];
  int i;
  strcpy(copy, input_string);
  for (i = 1, act = copy; i <= segment_number; i++, act = NULL) {
    sub = strtok_r(act, separator, &ptr);
    if (sub == NULL) break;
 return sub;