Tag Archives: Robotics

Change i2c address of ina219

Hi everyone,

I wanted to use ina219 with pca9685 but they shared the same i2c address 0x4:
download0.

Luckily, there’s a fairly easy fix for this. All we need to do is solder two pins together. We’re going to bridge a0 and this will change our address to 0x41.

In order to check these run sudo i2cdetect -y 1 pm the raspberry pi:
download

After soldering it becomes:
download

You can solder a combination of pins for different addresses:
None = 0x40 (default)
A0 = 0x41
A1 = 0x44 (the one I’ve soldered to get 44)
A0 + A1 = 0x45

Advertisements

A4988 Stepper motor RaspberryPi

We’re using a 42shd0034-20B Geetech stepping motor taken from a 3d printer:
download

We’ll be driving it with an A4988 stepper motor controller. You can pick up five packs of these for less than $2 online – definitely worth having a few extras around:
download

The datasheet is available here: https://www.pololu.com/file/download/A4988.pdf?file_id=0J450

The following diagram illustrates what we’ll be doing:
download

Once everything is connected it’ll end up looking something like this:
download

To start, connect your stepping and direction pins. I’ve used GPIO16 for stepping and GPIO21 for direction:
download

Each time GPIO16 is set to HIGH it will make the stepper motor take one step. When the direction pin is HIGH the stepper motor will go clockwise, when it’s LOW, anti-clockwise.

If you’re not using the sleep functionality, connect the RESET and SLP pins together and then wire them directly to 3.3v:
download

Using a separate power source wire 12v to the GND and VMOT pins. You should also place a capacitor across these pins as close to the board as possible. Generally the longest leg is positive. You’ll also need to connect the external GND to the Raspberry Pi’s GND:
download

Connect the four pins of the stepper motor:
download

Connect the A4988 to 3.3v and common GND:
download

The code is pretty straight forward but I’ve provided a class below to help you get started:


# System imports
import RPi.GPIO as GPIO
from time import sleep

class StepperHandler():

__CLOCKWISE = 1
__ANTI_CLOCKWISE = 0

def __init__(self, stepPin, directionPin, delay=0.208, stepsPerRevolution=200):

# Configure instance
self.CLOCKWISE = self.__CLOCKWISE
self.ANTI_CLOCKWISE = self.__ANTI_CLOCKWISE
self.StepPin = stepPin
self.DirectionPin = directionPin
self.Delay = delay
self.RevolutionSteps = stepsPerRevolution
self.CurrentDirection = self.CLOCKWISE
self.CurrentStep = 0

# Setup gpio pins
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
GPIO.setup(self.StepPin, GPIO.OUT)
GPIO.setup(self.DirectionPin, GPIO.OUT)

def Step(self, stepsToTake, direction = __CLOCKWISE):

print("Step Pin: " + str(self.StepPin) + " Direction Pin: " + str(self.DirectionPin) + " Delay: " + str(self.Delay))
print("Taking " + str(stepsToTake) + " steps.")

# Set the direction
GPIO.output(self.DirectionPin, direction)

# Take requested number of steps
for x in range(stepsToTake):
print("Step " + str(x))
GPIO.output(self.StepPin, GPIO.HIGH)
self.CurrentStep += 1
sleep(self.Delay)
GPIO.output(self.StepPin, GPIO.LOW)
sleep(self.Delay)

# Define pins
STEP_PIN = 16
DIRECTION_PIN = 21

# Create a new instance of our stepper class (note if you're just starting out with this you're probably better off using a delay of ~0.1)
stepperHandler = StepperHandler(STEP_PIN, DIRECTION_PIN, 0.0025)

# Go forwards once
stepperHandler.Step(200)

# Go backwards once
stepperHandler.Step(200, stepperHandler.ANTI_CLOCKWISE)

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

Could not find a version that satisfied the requirement smbus/python3-smbus

Hi everyone,

I ran into a bit of an issue installing smbus on Python3.5. It looks like all you have to do is use smbus2:

pip3.5 install smbus2

Collecting smbus2
Downloading smbus2-0.2.0.tar.gz
Building wheels for collected packages: smbus2
Running setup.py bdist_wheel for smbus2 … done
Stored in directory: /root/.cache/pip/wheels/90/71/b4/9f90d8e2d0349ab55fef07169a81bd8f925965f16174e2f809
Successfully built smbus2
Installing collected packages: smbus2
Successfully installed smbus2-0.2.0

Thanks to the following link: https://www.raspberrypi.org/forums/viewtopic.php?t=192909

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