Good introduction on LCD displays


If you ever wondered about how the ubiquitous cheap 20 character LCDs used in Arduino or RPI projects work then this video gives an easy explanation on their use. Gotta love the 8-bit guy. Also salvaged electronics to boot.


Experimenting with NinjaFlex


Decided to try NinjaFlex especially to try out this functional print Lightning-Aux holder by Maker1893

Got a trial size filament at Amazon NinjaFlex TPU Flexible Filament 1.75mm 50g Blush which on second thought seems incredibly overpriced.

Downloaded the recommended profile settings from NinjaFlex from PrintrBot Site

Fired up the printer and sent over sliced gcode via Octoprint

With the recommended settings from PB profile, the temperature settings seem to be very hot. Especially for the first few layers since the filament continuously dripped @225.

test cube below.

Printed the Lightning-Aux holder by Maker1893/a> with same settings


Meanwhile googling revealed a post by Matthew Mead on the same issue where he goes in into detail problems with NinjaFlex

Adapting from his post, here are before and after test cubes after tweaking the profile.  This is the bottom (first layer). Definitely an improvement.

Only changes are :

Printing Temperature: 215
Initial Layer Thickness : 0.3 mm
Bed Temperature : 40 (preheated this in Octoprint (not in Cura)


Do something cool with Amazon Dash button


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It is one of those times where you think why did I not think of that. Finally a good use for Amazon Dash buttons.

This guide shows you how to hack an Amazon Dash Button to shut down or reset your Raspberry Pi.

Source: Reboot or shut down your Raspberry Pi using an Amazon Dash Button

Docker Official support for Raspbian/Jessie

docker release 1.12  – finally adds support for raspbian on Arm. This is good news for Raspberry Pi. should make it easier for lot of folks to try their hand at containerization. The details are here .

Brought to you by the same folks at Hypriot. Who get into details here. Earlier the only way to get docker on RPi was to get HypriotOS.

Octoprint : Configure Email Notifier Plugin

ssh into your pi and type the following commands at the command line:

ssh pi@192.168.X.X
source ~/oprint/bin/activate
pip install yagmail

I had to do pip install yagmail. The plugin seems to indicate that it brings along yagmail.

This will give you the python prompt that the Email Notifier is talking about “>>>”.  Type the following into python:

import yagmail
yagmail.register('', 'MySecret')

Got an error :

RuntimeError: No recommended backend was available. Install the keyrings.alt package if you want to use the non-recommended backends. See README.rst for details.

Installed keyrings ; see others getting the same issue

source ~/oprint/bin/activate
pip install keyrings.alt
pip install yagmail
import yagmail
yagmail.register('', 'MySecret')

To test whether everything is right

yagmail.SMTP('').send('', 'subject', 'This is the body')

Note: If you have a single quote in your password, use double quotes to surround it instead of the single quotes I used. If you have both single quotes and double quotes in your password, then uh it’ll be more complicated.

Then press Ctrl-D to exit python.

OctoPi – Under Voltage issues



Have been struggling a lot with unreliable WiFi and more recently not being able to reconnect to router even after rebooting. Since the Octopi runs purely in headless mode I always suspected WiFi signal strength issues to be the cause for OctoPi going off my network and not being able to reconnect.

This is after trying to resolve signal coverage and strength issues by getting a signal extender which improved coverage and signal quality.

Connected to a monitor to troubleshoot.

Got a warning

fsck: Warning... fsck.vfat for device /dev/mmcblk0p1 exited with signal 6.
fsck died with exit status 8

Went into a rabbit hole of googling sd card errors and recovery procedures till I came across a forum posting where someone just mounted the sdcard on a windows machine and fixed the problem automagically. Guess what I do have a Win 8.1 machine. No harm in trying. As soon as the sd card was mounted windows detected that there was something wrong with it and graciously offered to fix it. Took the fixed card back to RPi and waited with a bated breath for it to boot up. To my surprise it booted up perfectly with no errors. So here is another anecdotal evidence supporting the automagical sd card healing properties of Windows.

But the elation was short lived. Got the omnius Rainbow Square on top right. Not steady but pulsating.

On researching found this Raspberry Pi • View topic – Under-voltage warnings. Note that it is being powered by a 2A supply from MCM. 

The warnings could be triggered both by power supply and usb cable.

So if you are running headless (which is usual with Octoprint) you have no way of knowing about the under voltage issue. Mike Redrobe has a solution to monitor this remotely.

I am suspecting the microUSB cable (microcenter) which works well for charging my umpteen other devices but somehow fails here. The only other device connected is the Edimax wireless dongle and RaspberryPi Camera.