Category Archives: Guides

Duinotech Hall Effect Sensor with RaspberryPi

Hi everyone,

This is just a quick post to cover how the Duinotech hall effect sensor module (XC-4434) can be hooked up to a RaspberryPi.

Sample Code

The code below will output a zero when the sensor is activated by a magnet, otherwise a zero.


import time
import datetime
import RPi.GPIO as GPIO

# Define constants
BUCKET_HALL_EFFECT_SIG_PIN = 14

# Setup GPIO pins
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
GPIO.setup(BUCKET_HALL_EFFECT_SIG_PIN, GPIO.IN, pull_up_down=GPIO.PUD_UP) # Important

while True:
print(str(GPIO.input(BUCKET_HALL_EFFECT_SIG_PIN))
time.sleep(0.5)

Wiring

Example

When near a magnetic field the light on the sensor will turn on. If you’re using the sample code above, a zero will be shown when close to a magnet, otherwise a 1.

Misc

Purchased from: https://www.jaycar.com.au/arduino-compatible-hall-effect-sensor-module/p/XC4434

Spec Sheet: Z7275

Updating to Python 3.5.1 on RaspberryPi

Hi everyone,

Just a quick post on how to update to Python 3.5.1 the normal upgrade process isn’t working for you:


cd ~
wget https://www.python.org/ftp/python/3.5.1/Python-3.5.1.tgz
tar -zxvf Python-3.5.1.tgz
cd Python-3.5.1
./configure && make && sudo make install

You may need to restart once this is complete. Run the following to confirm that the version is 3.5.1:

pi@raspberrypi:~ $ python3 --version
Python 3.5.1

Check out the following link for more info: https://stackoverflow.com/a/37079319/522859

Check Tensorflow Version – Raspbian

Hey everyone,

Just a quick post on how to check the Tensorflow version on Raspbian with a one-liner (assumes Python 3.x):


python3 -c 'import tensorflow as tf; print(tf.__version__)'

Check out this Stackoverflow post for more info: https://stackoverflow.com/a/38549357/522859

Check if String Contains a Substring – Python

Hey everyone,

Just a quick post on how to check if a string contains a string in python:

if "STRINGTOFIND" in "testtesttestSTRINGTOFINDtestesttest":
# continue

Thanks to this stackoverflow post: https://stackoverflow.com/a/5473023/522859

Arduino GPS – Ublox NEO-M8N Flight Controller GPS w/Protective Shell for PIX PX4 Pixhawk

Hey everyone,

I recently purchased this GPS unit on ebay: http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItemVersion&item=272492032614&view=all&tid=1865626885017

Unfortunately, I didn’t do a lot of research before getting it and had a bit of trouble finding any spec sheets or documentation. Just in case anyone else has the same problem I’ve listed out everything I needed to get it running below.

This is the wiring info you’ll need:
– VCC: red
– GND: black
– TXD: yellow
– RXD: white
– SCL: green
– SDA: blue

The default baud rate was 38400.

This is the example I ended up using to get a quick test up and running. Ensure that you map the rx and tx pins correctly (arduino tx to gps rx, arduino rx to gps tx).


v#include
#include
/*
This sample sketch demonstrates the normal use of a TinyGPS++ (TinyGPSPlus) object.
It requires the use of SoftwareSerial, and assumes that you have a
4800-baud serial GPS device hooked up on pins 4(rx) and 3(tx).
*/
static const int RXPin = 11, TXPin = 10;
static const uint32_t GPSBaud = 38400;

// The TinyGPS++ object
TinyGPSPlus gps;

// The serial connection to the GPS device
SoftwareSerial ss(RXPin, TXPin);

void setup()
{
Serial.begin(115200);
ss.begin(GPSBaud);

Serial.println(F("DeviceExample.ino"));
Serial.println(F("A simple demonstration of TinyGPS++ with an attached GPS module"));
Serial.print(F("Testing TinyGPS++ library v. ")); Serial.println(TinyGPSPlus::libraryVersion());
Serial.println(F("by Mikal Hart"));
Serial.println();
}

void loop()
{
// This sketch displays information every time a new sentence is correctly encoded.
while (ss.available() > 0)
if (gps.encode(ss.read()))
displayInfo();

if (millis() > 5000 && gps.charsProcessed() < 10) { Serial.println(F("No GPS detected: check wiring.")); while(true); } } void displayInfo() { Serial.print(F("Location: ")); if (gps.location.isValid()) { Serial.print(gps.location.lat(), 6); Serial.print(F(",")); Serial.print(gps.location.lng(), 6); } else { Serial.print(F("INVALID")); } Serial.print(F(" Date/Time: ")); if (gps.date.isValid()) { Serial.print(gps.date.month()); Serial.print(F("/")); Serial.print(gps.date.day()); Serial.print(F("/")); Serial.print(gps.date.year()); } else { Serial.print(F("INVALID")); } Serial.print(F(" ")); if (gps.time.isValid()) { if (gps.time.hour() < 10) Serial.print(F("0")); Serial.print(gps.time.hour()); Serial.print(F(":")); if (gps.time.minute() < 10) Serial.print(F("0")); Serial.print(gps.time.minute()); Serial.print(F(":")); if (gps.time.second() < 10) Serial.print(F("0")); Serial.print(gps.time.second()); Serial.print(F(".")); if (gps.time.centisecond() < 10) Serial.print(F("0")); Serial.print(gps.time.centisecond()); } else { Serial.print(F("INVALID")); } Serial.println(); }

Output should be something like this:

DeviceExample.ino
A simple demonstration of TinyGPS++ with an attached GPS module
Testing TinyGPS++ library v. 0.92
by Mikal Hart

Location: -27.427371,153.028945 Date/Time: 9/10/2017 06:04:21.40
Location: -27.427371,153.028945 Date/Time: 9/10/2017 06:04:21.40
LocatiaonfTGS+wh atahdSmlesiTiGS+bay .2b a at
ain Da/ie/ ai .Da/Te 1tion: -27.427371,153.028945 Date/Time: 9/10/2017 06:04:21.60
Location: -27.427371,153.028945 Date/Time: 9/10/2017 06:04:21.60
LocaS+bay .2b a at
ain Da/ie/ ai .Da/Te 1tion: -.aeTm1.
ti:.atTm:7cation: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:21.80
Location: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:21.80
Location: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:22.00
Location: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:22.00
Location: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:22.20
Location: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:22.20
Location: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:22.40
Locat/Te:/ an:3aTi: /1ain.atTm:7atn 3Dtie 1.cto.3teim 1.
ti: .aTim1aton: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:22.40
Location: -27.427368,153.028945 Date/Time: 9/10/2017 06:04:22.60
Location: -27.427368,153.028945 Datn 3Dtie 1.cto.3teim 1.

One final thing to note is that the blue light will start to flash once the GPS has a lock. You'll need a pretty open space, mine didn't work inside but got a lock within 60 seconds outside.

Let me know if you have any questions or links to better doco!

Rename all files in a directory with Sequential Numbers

Hey guys,

Just a batch script I came across that allows you to rename all files in a directory with sequential numbers. Really handy for things like tensorflow. All you need to do is create a batch file in the directory containing the following:

@echo off
setlocal EnableDelayedExpansion
set i=0
for %%a in (*.jpg) do (
    set /a i+=1
    ren "%%a" "!i!.new"
)
ren *.new *.jpg

 

Thanks to this stackoverflow post: https://superuser.com/a/350633/124014

Using FFMPEG to create an image for every second of a video

Hey guys,

Just a quick command I found on stackoverflow to take a still image/thumbnail out of a video every second:

ffmpeg -i video.avi -r 0.01979 -f image2 output_%05d.jpg

Thanks to this stackoverflow post: https://stackoverflow.com/a/14710478/522859

Start a Script on Startup – Raspberry Pi

Hey guys,

Just thought I’d leave a couple of links to some guides I came across for setting up boot scripts on a raspberry pi.

Quick guide on how to get them running: http://www.instructables.com/id/Raspberry-Pi-Launch-Python-script-on-startup/

How to delay the boot process until the network is available: https://raspberrypi.stackexchange.com/a/45774

Running ReadTheDocs on Windows

Hey everyone,

This is a quick guide on how to setup your own readthedocs server on Windows.

Install Python 2.7: https://www.python.org/downloads/

Install virtual env using pip via command prompt (run as administrator):
c:\Python27>python.exe scripts\pip.exe install virtualenv

Create a virtual environment:
c:\Python27>scripts\virtualenv.exe c:\readthedocs
c:\readthedocs\Scripts>activate.bat
(readthedocs) c:\readthedocs\Scripts>

Create a folder and clone the repository:
(readthedocs) c:\readthedocs\Scripts>md checkouts
(readthedocs) c:\readthedocs\Scripts>cd checkouts
(readthedocs) c:\readthedocs\Scripts\checkouts>git clone http://github.com/rtfd/readthedocs.org.git
Cloning into 'readthedocs.org'...
remote: Counting objects: 47896, done.
remote: Compressing objects: 100% (53/53), done.
remote: Total 47896 (delta 19), reused 0 (delta 0), pack-reused 47843
Receiving objects: 100% (47896/47896), 37.91 MiB | 8.76 MiB/s, done.
Resolving deltas: 100% (31783/31783), done.
Checking connectivity... done.

Get and install dependencies using pip:
(readthedocs) c:\readthedocs\Scripts\checkouts>cd readthedocs.org
(readthedocs) c:\readthedocs\Scripts\checkouts\readthedocs.org>git clone http://github.com/rtfd/readthedocs.org.git

Ran into the following error: no module named django.core.management (probably caused by having two version of python installed)
(readthedocs) c:\readthedocs\Scripts\checkouts\readthedocs.org>c:\Python27\python.exe c:\readthedocs\Scripts\pip.exe install django --upgrade
Collecting django
Using cached Django-1.10.2-py2.py3-none-any.whl
Installing collected packages: django
Successfully installed django-1.10.2
You are using pip version 8.1.1, however version 8.1.2 is available.
You should consider upgrading via the 'python -m pip install --upgrade pip' comm
and.

Build the database:
(readthedocs) c:\readthedocs\Scripts\checkouts\readthedocs.org>c:\Python27\pytho
n.exe C:\readthedocs\Scripts\checkouts\readthedocs.org\manage.py syncdb
Operations to perform:
Synchronize unmigrated apps: allauth, messages, django_extensions, django_grav
atar, rest_framework, annoying, textclassifier, corsheaders, copyright, privacy,
django_countries, humanize, rtd_tests, haystack, doc_builder, staticfiles, rest
api, bitbucket_oauth2, bitbucket, notifications, djangosecure, pagination, githu
b, djcelery, payments
Apply all migrations: core, account, builds, gold, sessions, admin, guardian,
tastypie, messages_extends, comments, sites, contenttypes, redirects, auth, tagg
it, oauth, bookmarks, donate, projects, socialaccount
Synchronizing apps without migrations:
Creating tables...
Creating table corsheaders_corsmodel
Creating table celery_taskmeta
Creating table celery_tasksetmeta
Creating table djcelery_intervalschedule
Creating table djcelery_crontabschedule
Creating table djcelery_periodictasks
Creating table djcelery_periodictask
Creating table djcelery_workerstate
Creating table djcelery_taskstate
Running deferred SQL...
Installing custom SQL...
Running migrations:
Rendering model states... DONE
Applying contenttypes.0001_initial... OK
Applying auth.0001_initial... OK
Applying account.0001_initial... OK
Applying account.0002_email_max_length... OK
Applying admin.0001_initial... OK
Applying contenttypes.0002_remove_content_type_name... OK
Applying auth.0002_alter_permission_name_max_length... OK
Applying auth.0003_alter_user_email_max_length... OK
Applying auth.0004_alter_user_username_opts... OK
Applying auth.0005_alter_user_last_login_null... OK
Applying auth.0006_require_contenttypes_0002... OK
Applying taggit.0001_initial... OK
Applying projects.0001_initial... OK
Applying builds.0001_initial... OK
Applying projects.0002_add_importedfile_model... OK
Applying bookmarks.0001_initial... OK
Applying builds.0002_build_command_initial... OK
Applying comments.0001_initial... OK
Applying core.0001_initial... OK
Applying core.0002_make_userprofile_user_a_onetoonefield... OK
Applying core.0003_add_banned_status... OK
Applying donate.0001_initial... OK
Applying donate.0002_dollar-drop-choices... OK
Applying donate.0003_add-impressions... OK
Applying donate.0004_rebase-impressions-on-base... OK
Applying donate.0005_add-geo-filters... OK
Applying donate.0006_add-geo-data... OK
Applying donate.0007_add-impression-totals... OK
Applying gold.0001_initial... OK
Applying guardian.0001_initial... OK
Applying messages_extends.0001_initial... OK
Applying sites.0001_initial... OK
Applying socialaccount.0001_initial... OK
Applying socialaccount.0002_token_max_lengths... OK
Applying oauth.0001_initial... OK
Applying oauth.0002_combine_services... OK
Applying oauth.0003_move_github... OK
Applying oauth.0004_drop_github_and_bitbucket_models... OK
Applying oauth.0005_add_account_relation... OK
Applying oauth.0006_move_oauth_source... OK
Applying oauth.0007_org_slug_nonunique... OK
Applying projects.0003_project_cdn_enabled... OK
Applying projects.0004_add_project_container_image... OK
Applying projects.0005_sync_project_model... OK
Applying projects.0006_add_domain_models... OK
Applying projects.0007_migrate_canonical_data... OK
Applying projects.0008_add_subproject_alias_prefix... OK
Applying projects.0009_add_domain_field... OK
Applying projects.0010_migrate_domain_data... OK
Applying projects.0011_delete-url... OK
Applying projects.0012_proper-name-for-install-project... OK
Applying projects.0013_add-container-limits... OK
Applying projects.0014_add-state-tracking... OK
Applying projects.0015_add_project_allow_promos... OK
Applying projects.0016_build-queue-name... OK
Applying projects.0017_add_domain_https... OK
Applying redirects.0001_initial... OK
Applying sessions.0001_initial... OK
Applying taggit.0002_auto_20150616_2121... OK
Applying tastypie.0001_initial... OK

Starting the readthedocs server:
D:\Users\ChrisO>C:\readthedocs\Scripts\activate.bat

(readthedocs) D:\Users\ChrisO>c:\Python27\python.exe C:\readthedocs\Scripts\chec
kouts\readthedocs.org\manage.py runserver
Performing system checks…

System check identified no issues (1 silenced).
October 21, 2016 – 11:16:17
Django version 1.8.3, using settings ‘readthedocs.settings.dev’
Starting development server at http://127.0.0.1:8000/
Quit the server with CTRL-BREAK.

Create a new readthedocsproject:
I followed this guide: http://read-the-docs.readthedocs.io/en/latest/getting_started.html#in-rst

Creating the new project:
C:\readthedocs>md whatibroke
C:\readthedocs>cd whatibroke
C:\readthedocs\whatibroke>C:\readthedocs\Scripts\sphinx-quickstart.exe
Welcome to the Sphinx 1.3.5 quickstart utility.

Please enter values for the following settings (just press Enter to
accept a default value, if one is given in brackets).

Installing a theme – sphinx_rtd_theme (optional step):
c:\readthedocs\Scripts>activate.bat
(readthedocs) c:\readthedocs\Scripts>cd c:\readthedocs\whatibroke
(readthedocs) c:\readthedocs\whatibroke>pip install sphinx_rtd_theme

In your conf.py file (C:\readthedocs\whatibroke\conf.py):
import sphinx_rtd_theme
html_theme = "sphinx_rtd_theme"
html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]

Building your output:
c:\readthedocs\Scripts>activate.bat
(readthedocs) c:\readthedocs\Scripts>cd c:\readthedocs\whatibroke
(readthedocs) c:\readthedocs\whatibroke>make html
Running Sphinx v1.3.5
loading pickled environment... done
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 0 source files that are out of date
updating environment: 0 added, 0 changed, 0 removed
looking for now-outdated files... none found
no targets are out of date.
build succeeded.

Build finished. The HTML pages are in _build/html.

Thanks to the following stackoverflow post for a lot of the information here: http://stackoverflow.com/a/19892345/522859