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by Idahowalker
Wed Feb 28, 2018 5:34 pm
Forum: Beginners
Topic: Inductance/Frequency measurement using rasberry pi
Replies: 14
Views: 2185

Re: Inductance/Frequency measurement using rasberry pi

Put the freq counter back to using 5 volts and use this as an interface to the Pi:

Image

I use that circuit to send and receive data from an Arduino to Pi, the circuits are bi-directional. Note the circuit acts as a pull up to inputs.
by Idahowalker
Tue Feb 27, 2018 5:30 pm
Forum: Python
Topic: Pi3, Python, PyQt and GPS
Replies: 8
Views: 1789

Re: Pi3, Python, PyQt and GPS

Type into the input box of your favorite search engine something like 'python gpio interrupts.' Press enter or click on the search icon/button to get a list of results like this one: How to use interrupts with Python on the Raspberry Pi and RPi.GPIO: http://raspi.tv/2013/how-to-use-interrupts-with-p...
by Idahowalker
Tue Feb 27, 2018 4:57 pm
Forum: Python
Topic: Pi3, Python, PyQt and GPS
Replies: 8
Views: 1789

Re: Pi3, Python, PyQt and GPS

scotty101 wrote:
Tue Feb 27, 2018 2:44 pm

Totally unnecessary to have an external timer.
QT comes with a timer that can be used to periodically schedule events, as I suggested in the post I linked to above.
Even better, the solution is right there and all one has to do is code for it.
by Idahowalker
Tue Feb 27, 2018 12:44 pm
Forum: Python
Topic: Pi3, Python, PyQt and GPS
Replies: 8
Views: 1789

Re: Pi3, Python, PyQt and GPS

You could use an interrupt to run the code. I got one of these: https://smile.amazon.com/gp/product/B01KZP9XTI/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1 I set the time out at one hour. My code bundles up some data, sends the data out in an email, and the code sets the timer to begin counting down ...
by Idahowalker
Mon Feb 26, 2018 10:39 pm
Forum: Automation, sensing and robotics
Topic: Accelerometer mouse
Replies: 9
Views: 1493

Re: Accelerometer mouse

@skars

How you doing on the project? Have you looked at the internet offerings on how to hook up and read an accelerometer to the RPi?

Have you broken your project down into some functions block diagrams, giving yourself a plan of attack?
by Idahowalker
Sun Feb 25, 2018 10:27 pm
Forum: Automation, sensing and robotics
Topic: Issues using a 5V Ultrasonic Sensor with Raspberry Pi
Replies: 3
Views: 907

Re: Issues using a 5V Ultrasonic Sensor with Raspberry Pi

Image

The above circuit can be used to pass data in either direction. I use this configuration to communicate between a Uno and a RPi3.

The circuit will default to pull ups on either side of the MOSFET.
by Idahowalker
Sun Feb 25, 2018 1:39 am
Forum: Automation, sensing and robotics
Topic: Accelerometer mouse
Replies: 9
Views: 1493

Re: Accelerometer mouse

From reading your posting is that you want a IMU package plugged into the RPi, you want the RPi plugged into a PC, and if the IMU is moved the mouse pointer on the PC is moved, correct? A good starting point is to do a search with "imu raspberry pi" using your favorite search engine as a start. Will...
by Idahowalker
Sat Feb 24, 2018 3:15 am
Forum: Beginners
Topic: LSM9DS1 to Dectect Telescope Position?
Replies: 7
Views: 1023

Re: LSM9DS1 to Dectect Telescope Position?

Perhaps a rotary encoder might be a better fit for this application.

https://en.wikipedia.org/wiki/Rotary_encoder
by Idahowalker
Sat Feb 24, 2018 1:06 am
Forum: Automation, sensing and robotics
Topic: BNO055 Linear Accelerometer Bias Drift (in motion)
Replies: 12
Views: 3605

Re: BNO055 Linear Accelerometer Bias Drift (in motion)

Something like this may be of help: https://www.raspberrypi.org/forums/viewtopic.php?f=37&t=205356#p1276047 Silly me, could you mark the beginning of each phase on the graph? It looks like to me that the accelerometer is 'seeing' acceleration during the rest and deacceleration phase. 'Thinking out l...
by Idahowalker
Thu Feb 22, 2018 6:22 pm
Forum: Beginners
Topic: Measure the voltage output of a PV module
Replies: 54
Views: 6021

Re: Measure the voltage output of a PV module

mahjongg wrote:
Thu Feb 22, 2018 6:18 pm
will be better off using a real ADC, on the I2C port.
I completely agree.
by Idahowalker
Thu Feb 22, 2018 4:57 pm
Forum: Beginners
Topic: Measure the voltage output of a PV module
Replies: 54
Views: 6021

Re: Measure the voltage output of a PV module

Oi! A battery is in use, a somewhat stable voltage source that can be used to compare the SolarCell voltage against. If you are comfortable using OP-AMPs in a conspirator configuration, three OP-AMPs could give you 3 different levels of comparison, low, mid and high. You could use three pins on the ...
by Idahowalker
Thu Feb 22, 2018 4:41 pm
Forum: Beginners
Topic: safety when using batteries close call!
Replies: 5
Views: 1041

Re: safety when using batteries close call!

Also, you might consider a reverse polarity protection circuit. Something as simple as this: https://cdn.instructables.com/FDG/EY20/H4AGK0SM/FDGEY20H4AGK0SM.RECT2100.jpg or https://beckustech.files.wordpress.com/2011/12/caramppowercircuit1.png If you are fine with working with a MOSFET something lik...
by Idahowalker
Wed Feb 21, 2018 7:35 pm
Forum: Beginners
Topic: Motor Control
Replies: 1
Views: 268

Re: Motor Control

type in search engine 'raspberry pi zero motor controller l298n' get this: http://www.instructables.com/id/Raspber ... -DC-Motor/ and many more entries.
by Idahowalker
Tue Feb 20, 2018 6:28 pm
Forum: Automation, sensing and robotics
Topic: Orientation of the mounted gyroscope and accelerometer's axis
Replies: 9
Views: 3315

Re: Orientation of the mounted gyroscope and accelerometer's axis

The offset of the Gyro can be read by placing the gyro on a flat surface and taking a measurement of the procession. Turn the gyro 180 degrees out of phase with the original position and measure the procession. Best to allow the gyro to settle for, say, 3 minutes, before taking measurements. Even be...
by Idahowalker
Tue Feb 20, 2018 5:31 pm
Forum: Python
Topic: Programming an emergency stop button
Replies: 8
Views: 1790

Re: Programming an emergency stop button

Raspberry Pi- GPIO Events in Python
https://stackoverflow.com/questions/161 ... -in-python
by Idahowalker
Tue Feb 20, 2018 1:09 pm
Forum: Python
Topic: Programming an emergency stop button
Replies: 8
Views: 1790

Re: Programming an emergency stop button

Code: Select all

switch = Button(2)  ##This is the safety switch & 2 buttons in series.
From reading the above, by wiring 2 buttons in series, 2 buttons have to be pressed for the safety to activate; an AND gate. Why not wire the buttons in parallel, an OR gate?
by Idahowalker
Fri Feb 16, 2018 5:07 pm
Forum: Beginners
Topic: Multiple connections to GND
Replies: 4
Views: 622

Re: Multiple connections to GND

Bring the ground (common) from the RPi to your project. From the point where the ground enters the project attach all the grounds (commons) to that single point. When I have multiple projects to connect, I use a bolt, that serves as the single ground point. I may place the bolt in one of the project...
by Idahowalker
Thu Feb 15, 2018 1:52 pm
Forum: Beginners
Topic: open relay using rpi and BC517
Replies: 7
Views: 876

Re: open relay using rpi and BC517

You mean like this:

Image
by Idahowalker
Wed Feb 14, 2018 11:02 pm
Forum: Python
Topic: variable courisity
Replies: 4
Views: 672

Re: variable courisity

Python has a bit of an usual but handy way of treating local/global variables. I subroutine can read any variable in the main routine without it needing to be declared as global but if a subroutine tries to change it then it will not change it but rather create a new local 1 with the same name. Tha...
by Idahowalker
Wed Feb 14, 2018 6:21 pm
Forum: Python
Topic: variable courisity
Replies: 4
Views: 672

variable courisity

So I write this line of code at the top of the module: import RPI.GPIO as GPIO Also at the top of the module, I have this 'global' variable: iPinIn2 = 4 I also have this 'global' variable declared: iTransientCount = 0 In a function, I have this line of code: def fSetUp(): ... GPIO.setup(iPinIn2, GPI...
by Idahowalker
Wed Feb 14, 2018 1:59 am
Forum: Python
Topic: Threading - Thread not consistent
Replies: 11
Views: 2439

Re: Threading - Thread not consistent

The 12V and RPi are connected through their common (gnd)? How so? A wire?

Does the 12V have motors, relays?
by Idahowalker
Tue Feb 13, 2018 12:05 am
Forum: Python
Topic: Threading - Thread not consistent
Replies: 11
Views: 2439

Re: Threading - Thread not consistent

as I have other thread with constant checking GPIO states Interrupts? def fDoTheThing(): try: fSetup() # event to read serial port GPIO.add_event_detect(iPinIn2, GPIO.RISING, callback=fCallBack) #event to clear latch GPIO.add_event_detect(iPinIn3, GPIO.RISING, callback=fCallBack, bouncetime = 20) G...
by Idahowalker
Mon Feb 12, 2018 10:14 pm
Forum: Beginners
Topic: gpio and running pi
Replies: 6
Views: 838

Re: gpio and running pi

Connect ground pin first, signal pins 2nd and power pin last. You know the risk with wrong pin connections.

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