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by ghellquist
Mon Jul 27, 2020 6:50 am
Forum: General discussion
Topic: course on C/C++ for raspbian
Replies: 5
Views: 306

Re: course on C/C++ for raspbian

Two things come to my mind when I read this (and no, this will not be an answer to finding a course). First: why not Python? It is a common misunderstanding that interpreted languages are slow. Well, that is a misunderstanding. Secondly: c and c++ are both very capable tools and you can easily make ...
by ghellquist
Tue Jul 21, 2020 6:38 am
Forum: General discussion
Topic: RPI 4: IPS and CPI?
Replies: 5
Views: 319

Re: RPI 4: IPS and CPI?

Hi! Check Help > Documentation > Hardware > RaspberryPi . The datasheet is here: https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2711/rpi_DATA_2711_1p0.pdf The CPU is based on the ARM Cortex-A72 design, see here https://developer.arm.com/documentation/100095/0003/ (Note that Cortex...
by ghellquist
Sun Jul 19, 2020 7:17 am
Forum: General discussion
Topic: Mic - not working
Replies: 4
Views: 326

Re: Mic

Hi Noura! Let us go back to the start. We in the forums want to help, but sometimes the offer for help might sound a little odd. It is very difficult for anyone to help you as you have forgotten to tell us some things. The error message simply says that the microphone can not be found by the program...
by ghellquist
Sat Jun 27, 2020 8:04 am
Forum: Off topic discussion
Topic: Wish list for the foundation
Replies: 53
Views: 6698

Wish list for the foundation

Your wishes on the next steps. Please, skip all the wishes for features on the next Pi on this thread. The foundation is doing a lot of fantastic things, bringing computing into economic reach for a lot of kids, allowing them to do hands-on with computers, making software useable and available (exam...
by ghellquist
Tue Jun 16, 2020 4:06 pm
Forum: General discussion
Topic: Raspberry vs Arduino industrial aplication
Replies: 19
Views: 893

Re: Raspberry vs Arduino industrial aplication

Too long to read: Don´t do it! This is a subject that contains one part theory, and many, many parts of experience. And might break quite a few laws and regulatorns. It can kill you or someone else, or, if you are lucky only get you into jail. Be warned. One industrial environment may be very differ...
by ghellquist
Wed Jun 10, 2020 6:06 pm
Forum: Beginners
Topic: Raspberry pi 4 and 4-20mA analog input
Replies: 2
Views: 202

Re: Raspberry pi 4 and 4-20mA analog input

You will need some extra hardware. The Raspberry does not have any analog inputs available. The 4-20 mA current loop can show a value from 0 to 100% (or how you want to scale the signal) and the values in between. An analog input would show that signal as a number, say from 0 to 32000 and then you s...
by ghellquist
Thu Jun 04, 2020 10:55 am
Forum: General discussion
Topic: Questions about programming on the Raspberry Pi
Replies: 20
Views: 1330

Re: Questions about programming on the Raspberry Pi

My question, what is the favourite language on the Raspberry Pi? There are so many to choose from. And each programmer has his or her own favourite. They go from assembly directly on the hardware over to Basic and C and C++ and Python and Perl and PHP and javascript and java and SQL and Ada and Erl...
by ghellquist
Sat Mar 07, 2020 11:18 am
Forum: General discussion
Topic: Which Raspberry Pi to buy?
Replies: 21
Views: 1428

Re: Which Raspberry Pi to buy?

My two cents. I get a picture in my head where you fill a RAM with the wave form in good time ahead. No hurry there and not much need for computing speed. You the "play" that waveform at GHz playback rate. I would probably look inte using a PC video card for the playback. A 4k video signal is well i...
by ghellquist
Sat Aug 18, 2018 7:50 am
Forum: General discussion
Topic: 4-20mA output
Replies: 16
Views: 8117

Re: 4-20mA output

Not a suggestion for buying, only a link to a product under for sale:
https://www.raspberrypi.org/forums/view ... 3&t=218521
//Gunnar
by ghellquist
Wed Jun 20, 2018 5:38 am
Forum: General discussion
Topic: Cheap Networking
Replies: 12
Views: 1475

Re: Cheap Networking

Do consider the speed you want, Raw speed on Ethernet 10 MBits/sec meaning 10,000,000, raw speed on serial perhaps 115,200.
by ghellquist
Tue Jun 19, 2018 4:28 pm
Forum: Advanced users
Topic: Pi3 as master, multiple Pi Zero W's reporting in... ... ...
Replies: 11
Views: 1661

Re: Pi3 as master, multiple Pi Zero W's reporting in... ... ...

We are absolutely trying to help you. But to us the requirements seems a bit hazy. They might be read as, when misunderstood: I have a greenhouse. I want to fill it with sensors and Raspberry Pi-s. I guess what you are trying to actually achieve is something slightly different. My guess is something...
by ghellquist
Sat Jun 16, 2018 5:59 am
Forum: Advanced users
Topic: Trouble with real-time code
Replies: 15
Views: 2876

Re: Trouble with real-time code

Is there a difference if you use isolcpus?
by ghellquist
Sun May 20, 2018 8:24 am
Forum: General discussion
Topic: Just throwing this out there: backdir
Replies: 26
Views: 2771

Re: Just throwing this out there: backdir

In one of my projects I use git exactly like this. No need for internet access and only a few commands to know. Understand that git and github is not the same thing --- GitHub adds a lot on top of git which you might elect to use or not. Preparation Create the folder where the project will be. Give ...
by ghellquist
Sun May 20, 2018 8:10 am
Forum: General discussion
Topic: Set up your WordPress Database
Replies: 2
Views: 1340

Re: Set up your WordPress Database

It helps if you include a link to the instructions your are following, or even better, copy them in you question. The databas mysql is used to store information used by the wordpress code. There is nothing special about that installation, but there are a number of steps you need to follow. It might ...
by ghellquist
Sun May 20, 2018 8:03 am
Forum: General discussion
Topic: Problem on MAX30105 sensor on Raspberry Pi 3
Replies: 14
Views: 2536

Re: Problem on MAX30105 sensor on Raspberry Pi 3

To other posters answering. There is a link to the actual bord the OP wants to use. As OP stated beting a beginner, we could be slightly more helpful here. The board can be directly attached to the Pi. The site says that you can run the board from 3,3V. One of the LED-s on the board will not work, ...
by ghellquist
Sat May 12, 2018 11:43 am
Forum: General discussion
Topic: Where to start? Do I use python for creating things or would I be better using JS or C or C++?
Replies: 15
Views: 2202

Re: Where to start? Do I use python for creating things or would I be better using JS or C or C++?

The most important factors in selecting a language, in my mind, are: 1- The support libraries that you easily use to tackle parts of your application. As example, if you need to manipulate pictures there are libraries that help with that. No need to write the code yourself. 2- The support you can ge...
by ghellquist
Tue Apr 24, 2018 4:27 pm
Forum: General discussion
Topic: Are Raspberry Pi and other microcontrollers scalable for commercial projects?
Replies: 13
Views: 1872

Re: Are Raspberry Pi and other microcontrollers scalable for commercial projects?

As one example you might look into OpenEnergyMonitor.

One setup uses temperature / humidity sensors powered by an Arduino. The emonTH then sends its data, sort of a few times a minute, over radiowaves. The central unit can be an RPi. Battery should last something like a year I believe.

/Gunnar
by ghellquist
Sun Feb 04, 2018 10:14 am
Forum: General discussion
Topic: Powered by XLR cable "Phantom Power" (+48V 14mA)?
Replies: 35
Views: 5234

Re: Powered by XLR cable "Phantom Power" (+48V 14mA)?

It will not work.

Phantom power is delivered to microphones starting with 48V. It goes through a resistor of 6810 Ohms. The power deriverad this way will not be sufficient to power a Raspberry.

https://en.wikipedia.org/wiki/Phantom_power

/Gunnar
by ghellquist
Sat Jul 15, 2017 9:24 am
Forum: Advanced users
Topic: Raspberry pi Zero - Analog audio input
Replies: 9
Views: 10556

Re: Raspberry pi Zero - Analog audio input

A bit off topic. But a bit of facts. Admittedly a bit simplified. Signal to noise rate is approximately 6 db per digital bit. The S/N then is the difference between the maximum signal and the "floor" of noise. CD-s are 16 bits, giving approximately 96db of S/N. There are no commercial audio converte...
by ghellquist
Sat Jul 15, 2017 9:13 am
Forum: Advanced users
Topic: Multiple pi cameras
Replies: 6
Views: 1464

Re: Multiple pi cameras

You will need to think about how much "jitter" you can accept in when the pictures are taken. For extreme precision, say below milliseconds, I am not sure you can make the standard Pi camera to react that fast. This will influence how you trigger the picture processes in the network of Pi-s. Dependi...
by ghellquist
Sat Jul 15, 2017 9:06 am
Forum: Advanced users
Topic: Raspberry Pi3 remote connect to PLC
Replies: 1
Views: 1805

Re: Raspberry Pi3 remote connect to PLC

This is definitely doable with a RPi. Telling us which type of PLCS might help us help a little better. Some ideas. - the PI has delicate digital inputs, so you will need some extra hardware to protect it. The Pi inputs are max 3.3 V. There are a lot of different solutions which you can buy ready-ma...
by ghellquist
Tue Jun 06, 2017 10:01 am
Forum: General discussion
Topic: Pi vs Microcontroller? (+Interrupts)
Replies: 28
Views: 11570

Re: Pi vs Microcontroller? (+Interrupts)

There is a function I have contemplated to investigate. The function isolcpus in Linux allows us to reserve one (or more) CPU-s. Since the rpi 2 and 3 has four CPU-s, we could reserve one for realtime work. A control loop could run there, more ore less isolated from the rest of the Linux system. The...
by ghellquist
Sun May 22, 2016 8:08 am
Forum: Networking and servers
Topic: How could I host a website totally on my R pi ?
Replies: 6
Views: 18355

Re: How could I host a website totally on my R pi ?

You will need four things. 1) The OS Raspbian will be fine (the supported "standard" for Pi) 2) Install the programs Search for LAMP - Linux, Apache, Mysql and PHP Apache is the web server Mysql the database PHP one common language used on web sites 3) Create your website Writing html is one way to ...
by ghellquist
Thu Apr 28, 2016 4:36 am
Forum: Beginners
Topic: I2C read starts from arbitary register
Replies: 10
Views: 2949

Re: I2C read starts from arbitary register

Reading the data sheet, it says the following. 1) Tell the device which adress you want to read from. This requires you to send three bytes of data: device select, address byte, address byte. Here the R/W bit should be 0 in the select. 2) Read the data: You send device select, the devices responds w...
by ghellquist
Sun Mar 13, 2016 9:19 am
Forum: General discussion
Topic: 4x4 membrane keypad
Replies: 13
Views: 5422

Re: 4x4 membrane keypad

I believe what you experience here is real world vis computer program. In order to read the ROW input you need to wait for the electrical signals to calm down. So insert a short delay after outputting COL until reading ROW.

/Gunnar

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