Category Archives: RaspberryPi

AWS IoT – error in discovery certificate_verify_failed

Hi everyone,

I ran into the following error while using the AWS IoT python SDK:

Error in discovery!
Type: 
Error message: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:720)

It turns out that this was because I was using the wrong root certificate. In the documentation there are five certificates listed:

  • RSA 2048 bit key: VeriSign Class 3 Public Primary G5 root CA certificate
  • RSA 2048 bit key: Amazon Root CA 1
  • RSA 4096 bit key: Amazon Root CA 2
  • ECC 256 bit key: Amazon Root CA 3
  • ECC 384 bit key: Amazon Root CA 4

If you’re using the console to create the certificate and have already downloaded your device cert, public cert and private key you can use Amazon Root CA 1: https://www.amazontrust.com/repository/AmazonRootCA1.pem

As soon as that was added the error was resolved and I was able to move onto the next one. I found most of the info on the AWS forums but let me know if you have any questions: https://forums.aws.amazon.com/thread.jspa?threadID=286871

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Update Wireless Info on Raspberry Pi

Hi everyone,

Just a quick post on how to configure wireless info on a raspberry pi. To start with, open the config file:

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

You can then add any number of connections to the file with varying priorities:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=AU

network={
        ssid="Mobile Network"
        psk="YOUR_PASSWORD"
        key_mgmt=WPA-PSK
        priority=2
}

network={
        ssid="Home Network"
        psk="YOUR_PASSWORD"
        key_mgmt=WPA-PSK
        priority=10
}

Then save the file. Your raspberry pi will now connect to the network with the highest priority first (home network), when that’s not available it will use the network with the lower priority (mobile network).

The official doco is actually pretty good for this use case if you need more info: https://www.raspberrypi.org/documentation/configuration/wireless/wireless-cli.md

Using INA219 (GY-219) with the Raspberry Pi

Hi everyone,

I’ve just setup an INA219B Voltage/Current sensor on my RaspberryPi. Just thought I’d link the tutorials and libraries I used – there’s a lot of really useful info out there.

Install the following library via git: https://github.com/chrisb2/pi_ina219
sudo pip3 install pi-ina219

Follow this tutorial: https://www.rototron.info/raspberry-pi-ina219-tutorial/

Misc Notes

  • Common ground is required
  • Vin – and Vin+ are attached to +, neither goes to ground

Custom Sensor Address
na = INA219(SHUNT_OHMS, MAX_EXPECTED_AMPS, address=0x41)

Can be configured via the following:

Enable Low Power Between Reads
ina.configure(ina.RANGE_16V)
while True:
print "Voltage : %.3f V" % ina.voltage()
ina.sleep()
time.sleep(60)
ina.wake()

If you’re getting the following error:

OSError: [Errno 121] Remote I/O error

Run the following command:

i2cdetect -y 1

And check to ensure that your device is showing up on 40. If it’s a different number you’ll just need to update the address in your code e.g. (0x40, 0x41, etc.)

Mini-360 DC-DC Buck Converter – Incorrect Voltage 10v Instead of 5v

Hi everyone,

I’ve been playing around with a few DC-DC buck converters similar to these ones: https://www.amazon.com.au/UEB-Power-Converter-Module-Supply/dp/B078CXHWXC/ref=sr_1_fkmr1_1?ie=UTF8&qid=1519030369&sr=8-1-fkmr1&keywords=mini+360+buck+converter

I had expected 5v output from my 12v supply but when I hooked it up to a multimeter I found I was getting just over 10v. This would fry pretty much everything in my circuit so I was pretty worried.

After a bit of research, I came across a thread on eevblog that mentioned a screw for adjustment. Looking closely you can see that there is a small screw on the side of the chip. Turning this quarter of a rotation anti-clockwise put mine at exactly 5.04 volts.

A few other small tips:

  • The thread seems to indicate that some models require a lot more turning (up to 30 seconds for one poster).
  • I had to push down fairly hard to get it to actually turn the part underneath instead of just the metal cover

Hopefully this helps someone else out!

Eevblog: https://www.eevblog.com/forum/beginners/dc-dc-buck-converter-step-down-module-lm2596-power-supply/

Thanks,
Chris

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

Pillow Install Fails – Python 3.5.2

Hi everyone,

Pillow install fails

I ran into a bit of an issue trying to install Pillow on Raspbian with Python 3.5.2. The full error is below, but the solution was simply to install the following:

sudo apt-get install libjpeg8-dev
sudo pip3.5 install pillow

sudo pip3.5 install pillow
Collecting pillow
Using cached Pillow-4.3.0.tar.gz
Requirement already satisfied: olefile in /usr/local/lib/python3.5/site-packages (from pillow)
Installing collected packages: pillow
Running setup.py install for pillow … error
Complete output from command /usr/local/bin/python3.5 -u -c “import setuptools, tokenize;__file__=’/tmp/pip-build-inj0l_9q/pillow/setup.py’;f=getattr(tokenize, ‘open’, open)(__file__);code=f.read().replace(‘rn’, ‘n’);f.close();exec(compile(code, __file__, ‘exec’))” install –record /tmp/pip-xp_x4w_5-record/install-record.txt –single-version-externally-managed –compile:
running install
running build
running build_py
creating build
creating build/lib.linux-armv7l-3.5
creating build/lib.linux-armv7l-3.5/PIL
copying PIL/MicImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageMath.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/WebPImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImagePath.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageGrab.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/SunImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/__init__.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageEnhance.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageMorph.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/XpmImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/EpsImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/FtexImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/WmfImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/FitsStubImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageDraw2.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/IptcImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/_binary.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/MpoImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/Hdf5StubImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/Image.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/MspImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageWin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/GimpPaletteFile.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageTk.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/PSDraw.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/McIdasImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/SgiImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageStat.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageChops.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/PdfImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/features.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/PcfFontFile.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/PcxImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageOps.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImagePalette.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/TgaImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageSequence.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/_util.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/TiffTags.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/BmpImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/DdsImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ExifTags.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/PyAccess.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/PpmImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageCms.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/PaletteFile.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/XVThumbImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/IcoImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageFilter.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageFont.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/GifImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/GbrImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/XbmImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/PngImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/FontFile.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/IcnsImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/TiffImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/_tkinter_finder.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/DcxImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/OleFileIO.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/SpiderImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/JpegImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/GribStubImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/MpegImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/PalmImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/BdfFontFile.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/GimpGradientFile.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/PsdImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/WalImageFile.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageFile.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/PcdImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/version.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/FpxImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageQt.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/Jpeg2KImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageDraw.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/GdImageFile.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ContainerIO.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/CurImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/FliImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageMode.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/JpegPresets.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/PixarImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageColor.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/BufrStubImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageTransform.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImageShow.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/TarIO.py -> build/lib.linux-armv7l-3.5/PIL
copying PIL/ImtImagePlugin.py -> build/lib.linux-armv7l-3.5/PIL
running egg_info
writing dependency_links to Pillow.egg-info/dependency_links.txt
writing requirements to Pillow.egg-info/requires.txt
writing top-level names to Pillow.egg-info/top_level.txt
writing Pillow.egg-info/PKG-INFO
warning: manifest_maker: standard file ‘-c’ not found

reading manifest file ‘Pillow.egg-info/SOURCES.txt’
reading manifest template ‘MANIFEST.in’
warning: no files found matching ‘*.sh’
no previously-included directories found matching ‘docs/_static’
warning: no previously-included files found matching ‘.coveragerc’
warning: no previously-included files found matching ‘codecov.yml’
warning: no previously-included files found matching ‘.editorconfig’
warning: no previously-included files found matching ‘.landscape.yaml’
warning: no previously-included files found matching ‘.travis’
warning: no previously-included files found matching ‘.travis/*’
warning: no previously-included files found matching ‘appveyor.yml’
warning: no previously-included files found matching ‘build_children.sh’
warning: no previously-included files found matching ‘tox.ini’
warning: no previously-included files matching ‘.git*’ found anywhere in distribution
warning: no previously-included files matching ‘*.pyc’ found anywhere in distribution
warning: no previously-included files matching ‘*.so’ found anywhere in distribution
writing manifest file ‘Pillow.egg-info/SOURCES.txt’
running build_ext

The headers or library files could not be found for jpeg,
a required dependency when compiling Pillow from source.

Please see the install instructions at:
https://pillow.readthedocs.io/en/latest/installation.html

Traceback (most recent call last):
File “/tmp/pip-build-inj0l_9q/pillow/setup.py”, line 787, in
zip_safe=not (debug_build() or PLATFORM_MINGW), )
File “/usr/local/lib/python3.5/distutils/core.py”, line 148, in setup
dist.run_commands()
File “/usr/local/lib/python3.5/distutils/dist.py”, line 955, in run_commands
self.run_command(cmd)
File “/usr/local/lib/python3.5/distutils/dist.py”, line 974, in run_command
cmd_obj.run()
File “/usr/local/lib/python3.5/site-packages/setuptools/command/install.py”, line 61, in run
return orig.install.run(self)
File “/usr/local/lib/python3.5/distutils/command/install.py”, line 539, in run
self.run_command(‘build’)
File “/usr/local/lib/python3.5/distutils/cmd.py”, line 313, in run_command
self.distribution.run_command(command)
File “/usr/local/lib/python3.5/distutils/dist.py”, line 974, in run_command
cmd_obj.run()
File “/usr/local/lib/python3.5/distutils/command/build.py”, line 135, in run
self.run_command(cmd_name)
File “/usr/local/lib/python3.5/distutils/cmd.py”, line 313, in run_command
self.distribution.run_command(command)
File “/usr/local/lib/python3.5/distutils/dist.py”, line 974, in run_command
cmd_obj.run()
File “/usr/local/lib/python3.5/distutils/command/build_ext.py”, line 338, in run
self.build_extensions()
File “/tmp/pip-build-inj0l_9q/pillow/setup.py”, line 577, in build_extensions
raise RequiredDependencyException(f)
__main__.RequiredDependencyException: jpeg

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File “”, line 1, in
File “/tmp/pip-build-inj0l_9q/pillow/setup.py”, line 799, in
raise RequiredDependencyException(msg)
__main__.RequiredDependencyException:

The headers or library files could not be found for jpeg,
a required dependency when compiling Pillow from source.

Please see the install instructions at:
https://pillow.readthedocs.io/en/latest/installation.html

—————————————-
Command “/usr/local/bin/python3.5 -u -c “import setuptools, tokenize;__file__=’/tmp/pip-build-inj0l_9q/pillow/setup.py’;f=getattr(tokenize, ‘open’, open)(__file__);code=f.read().replace(‘rn’, ‘n’);f.close();exec(compile(code, __file__, ‘exec’))” install –record /tmp/pip-xp_x4w_5-record/install-record.txt –single-version-externally-managed –compile” failed with error code 1 in /tmp/pip-build-inj0l_9q/pillow/

Thanks to the comment on the following Stackoverflow post for the solution: https://stackoverflow.com/a/34631976/522859

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