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by ghellquist
Sat May 23, 2015 8:29 am
Forum: Networking and servers
Topic: I want to start my 1st rasberryPi project
Replies: 4
Views: 920

Re: I want to start my 1st rasberryPi project

Second post: My project is going to be like a "KeyVault" safe system. The idea is , someone with internet access will goto a website, and place "information" into the database. This information can be anything at all, but once it hits the database, its encrypted. So now a hacker can't read the impor...
by ghellquist
Sat May 23, 2015 8:24 am
Forum: Networking and servers
Topic: I want to start my 1st rasberryPi project
Replies: 4
Views: 920

Re: I want to start my 1st rasberryPi project

Use raspberry as operation system. --> rationale: implementing tcp/ip with trimmings such as ssh needed to access the internet takes at a guess 100.000 lines of code, already there Select a high level programming language, not ASM --> never program in ASM unless you really love it (few do) or absolu...
by ghellquist
Sat May 23, 2015 8:13 am
Forum: Networking and servers
Topic: [Raspbian] Dynamically changing IP address for the Raspberry
Replies: 9
Views: 988

Re: [Raspbian] Dynamically changing IP address for the Raspb

Is there any way to achieve this transition from server to client or can I register it as both?

Both at the same time. Run the client as one process, the server as a different process.
The small character & in shell starts a command in the background.
// Gunnar
by ghellquist
Fri May 22, 2015 7:09 pm
Forum: Networking and servers
Topic: [Raspbian] Dynamically changing IP address for the Raspberry
Replies: 9
Views: 988

Re: [Raspbian] Dynamically changing IP address for the Raspb

Check out DHCP

One computer on the net as master, possibly the PC.
//Gunnar
by ghellquist
Mon Apr 13, 2015 9:34 pm
Forum: Troubleshooting
Topic: USB HDD stopped working
Replies: 19
Views: 2063

Re: USB HDD stopped working

Possible cause -- if you mount it as /dev/sda.

The reason is that the /dev/sda might (without any reason known to humans) change into /dev/sdb at any time. It is all in how USB works.
The solution is to mount the disc as UUID instead. (google: linux mount uuid )

// Gunnar
by ghellquist
Mon Apr 13, 2015 7:37 pm
Forum: Other programming languages
Topic: Erlang
Replies: 13
Views: 7121

Re: Erlang

It helped for me to think about the creation of Erlang as a solution to a set of problems. The language design as such came partly as result of that, partly as a result of the culture some of the people doing the work came from. My interpretation of the history (which probably is very inaccurate) ce...
by ghellquist
Sun Mar 22, 2015 9:47 pm
Forum: General discussion
Topic: FPGA with a Raspberry Pi to crack passwords
Replies: 20
Views: 5068

Re: Password Cracking with an FPGA and Raspberry Pi

Please go easy. "Students in grades 7-12 are invited yearly to participate in one (1) of the PJAS Regional Competitions" rpiswag -- I believe this might be aiming a bit too high. Crypto is about mathematics most of us do not meet until well into university level. You might be able to find a route th...
by ghellquist
Thu Mar 12, 2015 5:49 am
Forum: Automation, sensing and robotics
Topic: Remote Temp Humudity
Replies: 2
Views: 567

Re: Remote Temp Humudity

Check out this for inspiration. It has what you are asking for: remote sensor with temp and humidity which runs a year on battery, radio communication, central RPI for either storage of database or passin on the net to a central server.

http://openenergymonitor.org/emon/modules/emonTH

// Gunnar
by ghellquist
Mon May 05, 2014 7:48 pm
Forum: Automation, sensing and robotics
Topic: Radar with radio distance sensor
Replies: 7
Views: 6271

Re: Radar with radio distance sensor

Oops! Hope you can find a solution. Only remember that radar signals runs at speed of light, 299 792 458 m / s. (well, slightly slower). If you need a resolution of a decimeter, you need to clock the measuring function at about 3GHz.
by ghellquist
Sat Apr 26, 2014 8:45 pm
Forum: Automation, sensing and robotics
Topic: Allen Bradley comm.
Replies: 7
Views: 7276

Re: Allen Bradley comm.

I assume you have checked this page: http://en.wikipedia.org/wiki/DF-1_Protocol There will be a bit of worked involved. Firstly, the hardware part: - the pi used 3.3V signals. - the PLC used Rs232. = this means you will need to have circuits in between, integrated circuits doing this saves a lot of ...
by ghellquist
Thu Feb 27, 2014 7:16 am
Forum: Beginners
Topic: How do you create a new file in /proc
Replies: 1
Views: 390

Re: How do you create a new file in /proc

/proc is not a normal folder. You cannot store any files there. Instead /proc is a pseudo file system showing various kernel data, such as running processes on the system. It is one of the ways Linux making "everything is a file" work. It allows programs to read and sometimes modify system data stru...
by ghellquist
Wed Jan 22, 2014 6:43 am
Forum: General discussion
Topic: Virtual RAM
Replies: 8
Views: 2280

Re: Virtual RAM

Yes. That is what swapping is about. Linux does this if you enable swapping. The problem is that things start running very slow.

// Gunnar
by ghellquist
Sat Jan 11, 2014 9:10 am
Forum: Advanced users
Topic: Personal Area Network using contiki os
Replies: 4
Views: 1583

Re: Personal Area Network using contiki os

Could you be more clear on what you want to achieve, might make it easier to give an answer? - run contiki-os on the raspberry pi - run programs developed for contiki-os on a raspberry pi running linux - develop contiki-os motes on a raspberry - setup a raspberry pi as "central server" for a network...
by ghellquist
Sat Dec 28, 2013 9:49 pm
Forum: Beginners
Topic: BMP085 shows altitude in negative
Replies: 2
Views: 1154

Re: BMP085 shows altitude in negative

The standard calculations for this device assumes 1013.25 hPa at sea level. As you read higher pressure, you need to be below sea level :)

Actual pressure at sea level changes due to wheather.
http://en.wikipedia.org/wiki/Atmospheric_pressure
by ghellquist
Sat Dec 28, 2013 8:47 am
Forum: Beginners
Topic: malware listed from win32 download exc
Replies: 8
Views: 1007

Re: malware listed from win32 download exc

Sorry, think you are asking the wrong forum. This forum is about Raspberry Pi and some about Linux. Your question is about malware on a windows machine.
by ghellquist
Sat Dec 28, 2013 8:34 am
Forum: Beginners
Topic: Get started with Pi without any external hardware?
Replies: 26
Views: 3739

Re: Get started with Pi without any external hardware?

Just learnt existence of IPMI and other KVM-over-LAN. Is such a thing in the plans yet for the Pi? You can expect Linux to have solutions to just about any problem. Maybe not exactly the same solution as other platforms. As for KVM-over-Ip: Raspian uses tightvnc for the "server" end in the Pi. This...
by ghellquist
Sat Dec 28, 2013 8:26 am
Forum: Beginners
Topic: Get started with Pi without any external hardware?
Replies: 26
Views: 3739

Re: Get started with Pi without any external hardware?

Raw images (from Downloads) can be run headless from the beginning using SSH.

NOOBS needs a little "tweak" before first start, see here:
https://github.com/raspberrypi/noobs#ho ... tall-an-os

// Gunnar
by ghellquist
Sat Dec 28, 2013 8:23 am
Forum: Beginners
Topic: Get started with Pi without any external hardware?
Replies: 26
Views: 3739

Re: Get started with Pi without any external hardware?

Cubytus wrote:Why would I need Putty?
I understood that Rasbpian already had SSH enabled, isn't it the case?
Right. Putty is the SSH terminal you use in your PC, the "other end" so to say.
by ghellquist
Sun Dec 22, 2013 8:52 am
Forum: Automation, sensing and robotics
Topic: PID PWM controld fan
Replies: 7
Views: 33602

Re: PID PWM controld fan

Does it help with this explanation. You need to run the control loop cyclically, say once every second. It depends on how fast the real world reacts to changes in fan speed. In order for the calculations to be reasonably simple you want the cycle time to be fairly constant, not varying widely from t...
by ghellquist
Fri Dec 20, 2013 9:36 pm
Forum: Automation, sensing and robotics
Topic: antenna rotator and software to control
Replies: 17
Views: 14367

Re: antenna rotator and software to control

Using a Pi is definitely nice, but sort of a bit of overkill. To control the system you basically need one three position switch per motor (up stop down, left stop right) and to see where it is pointing you can start by looking out the window. A display of direction could be done using a potentiomet...
by ghellquist
Fri Dec 20, 2013 9:24 pm
Forum: Bare metal, Assembly language
Topic: Raspberry Pi PLC Assembly OS
Replies: 8
Views: 10422

Re: Raspberry Pi PLC Assembly OS

As for examples of text PLC languages, do a google on "plc instruction list". This is a simple assembler type language which rather easily can be implemented with an interpreter. I would probably implement it as a byte code interpreter: 1) translation phase: the instruction list is read and parsed a...
by ghellquist
Fri Dec 20, 2013 8:41 am
Forum: Bare metal, Assembly language
Topic: Raspberry Pi PLC Assembly OS
Replies: 8
Views: 10422

Re: Raspberry Pi PLC Assembly OS

PLC on raspberry. The important first question to ask is what guaranteed max response time you need from changed input to changed output. In some applications a PLC needs to respond in a few milliseconds. This is difficult to achieve on the Raspberry using an OS, you will need to do some low-level c...
by ghellquist
Sat Dec 14, 2013 2:34 pm
Forum: Advanced users
Topic: How to add package to a new embedde linux ?
Replies: 5
Views: 1212

Re: How to add package to a new embedde linux ?

Just thinking here. You probably know something I do not. The standard distributions has a lot of functions and is not minimal. But just about every one of those functions simply sits on the SD card and does nothing until you start them. No RAM memory used, no CPU cycles used. The graphic is not doi...
by ghellquist
Sat Dec 14, 2013 9:58 am
Forum: Beginners
Topic: First experience - horrible
Replies: 48
Views: 7189

Re: First experience - horrible

Please! Accept the user story as told. Don´t kill the messenger. Instead take the story as input on how to make things better. This story and similar ones will happen again and again. The important part for us as a community is to read them as real world experiences. And thank the person for showing...
by ghellquist
Sat Dec 14, 2013 9:38 am
Forum: Beginners
Topic: You say this is to encourage child programming???
Replies: 13
Views: 2575

Re: You say this is to encourage child programming???

One suggestion: check out Magpi Issue 19, page 10. There is a lot of information on how to read sensors, log the values, send them on or present them on a web page scattered all over this forum. It takes a bit of training on how to search in order to find the information though. Currently, the prefe...

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