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by jahboater
Wed Feb 03, 2016 8:52 am
Forum: General discussion
Topic: Just got my first RPi2.
Replies: 13
Views: 1718

Re: Just got my first RPi2.

And some of those are extensions, not ARM (NEON, thumb/thumb2). I don't think thumb2 is an extension, some v7 processors (the Cortex-M series) support thumb2 only. If you are using UAL which people should be now, it doesn't matter anyway. RISC OS does not use them either. That's sad, there is a rea...
by jahboater
Tue Feb 02, 2016 11:28 am
Forum: General discussion
Topic: Just bought my second Pi 2
Replies: 13
Views: 2487

Re: Just bought my second Pi 2

Adrianfu wrote:Ok its the start of an adiction
Interference in only on AM radio and my HF radio gear
Four Pi2's, two Pi Zero's, two B+, one B - older ones given away to schools.
Perhaps the interference is down to the switching regulators?
by jahboater
Tue Feb 02, 2016 9:36 am
Forum: General discussion
Topic: Just got my first RPi2.
Replies: 13
Views: 1718

Re: Just got my first RPi2.

Its more than that:- It has NEON which is a very fast SIMD instruction set (NEON does integer arithmetic too - including 64-bit). It has full 16-bit immediate operands for MOV and the new MOVT (two insns for a 32-bit register load) It has ARM hardware integer division instructions (SDIV and UDIV) It...
by jahboater
Sun Jan 31, 2016 1:39 pm
Forum: Advanced users
Topic: Overclocking
Replies: 1125
Views: 605056

Re: Overclocking

The thing is, if you need "vcgencmd schmoo" to make your RAM stable, it's entirely possible the system won't make it as far as /etc/rc.local or /storage/.config/autostart.sh etc. before crashing due to sdram issues...
Agreed.
The thermal inertia of a heatsink might help during the boot.
by jahboater
Sun Jan 31, 2016 1:12 pm
Forum: Advanced users
Topic: Overclocking
Replies: 1125
Views: 605056

Re: Overclocking

I added vcgencmd only, to /etc/rc.local.
I don't use force turbo, so I think the ondemand governor will change the frequencies the first time you run a cpu intensive command (and if you never run such a command, you don't need the overclock!)
by jahboater
Sun Jan 31, 2016 10:36 am
Forum: Advanced users
Topic: pigpio vs. wiringpi
Replies: 5
Views: 6264

Re: pigpio vs. wiringpi

There must be some advantage for using one over the other (speed, efficiency, memory footprint, etc.). Why don't you just try all three libraries for something simple at first and see how you get on? Perhaps do some measurements. Joan is a frequent, and obviously highly knowledgeable, contributor t...
by jahboater
Sun Jan 31, 2016 9:54 am
Forum: C/C++
Topic: gcc5 repository
Replies: 10
Views: 5424

Re: gcc5 repository

I added:- --disable-softfloat \ --enable-languages=c to try and speed things up a little, which may reduce the swap needed, I don't know. The configure in your build instructions looks better ../gcc-src/configure -v --enable-languages=c,c++ \ --prefix=/usr/local/gcc-5.3 --with-arch=armv7-a \ --with-...
by jahboater
Sat Jan 30, 2016 6:19 pm
Forum: C/C++
Topic: gcc5 repository
Replies: 10
Views: 5424

Re: gcc5 repository

My recollection is a that few hours means about 8 when compiling on the Pi 2B. Note that you will need a 2 GB swap file for the compilation to finish. It all depends on how long you have - "make" or "make -j1" will take nearly two days, but will succeed without any extra swap space. As you increase...
by jahboater
Fri Jan 29, 2016 1:12 pm
Forum: C/C++
Topic: gcc5 repository
Replies: 10
Views: 5424

Re: gcc5 repository

I use GCC 5.3 on the Pi2.
I don't think you can get it from the repositories.
You will have to build it yourself which takes a few hours!
by jahboater
Fri Jan 29, 2016 9:41 am
Forum: Other projects
Topic: R Pi 2 case
Replies: 4
Views: 1352

Re: R Pi 2 case

What does this box actually cool. They refer to the "chipset" ?? do they mean the sdram chip I wonder. There are three issues:- 1) damage or reduced longevity due to overheating This is a non-issue. The RPF have had no Pi's returned due to over heat damage. The chip is very robust. The expected life...
by jahboater
Thu Jan 28, 2016 8:47 pm
Forum: General discussion
Topic: How to connect and use ssh without a screen using BUILDROOT
Replies: 6
Views: 1825

Re: How to connect and use ssh without a screen using BUILDR

You are using a B+, seriously, for something like face recognition you really should get a Pi2 - four CPU's, NEON, 1GB ram amongst other things.
by jahboater
Thu Jan 28, 2016 9:10 am
Forum: Beginners
Topic: raspberry pi 100% cpu usage
Replies: 11
Views: 4307

Re: raspberry pi 100% cpu usage

What kind of Pi is this running on? The Pi2 has four CPU's, so if your program takes up 100% of one CPU its no big deal, the system will continue to be very fast with the remaining three - and each CPU is considerably quicker. The Pi2 also has the NEON SIMD instruction set which can speed up image p...
by jahboater
Tue Jan 26, 2016 11:27 pm
Forum: Advanced users
Topic: Overclocking
Replies: 1125
Views: 605056

Re: Overclocking

I added those lines to config.txt with your suggested values and I'm stable at
Did you mean config.txt? It looked to me like /etc/rc.local might be the best place for vcgencmd.
by jahboater
Tue Jan 26, 2016 4:07 pm
Forum: Beginners
Topic: Unzip raspbian download on Raspberry Pi
Replies: 5
Views: 806

Re: Unzip raspbian download on Raspberry Pi

It normally does. The output file ends with ".img". Did you run unzip from the command line?
There is a -d option to send the unzipped files elsewhere, but you would have known had you used that.
The full Jessie image is well over 4GB by the way.
by jahboater
Tue Jan 26, 2016 3:40 pm
Forum: Beginners
Topic: Unzip raspbian download on Raspberry Pi
Replies: 5
Views: 806

Re: Unzip raspbian download on Raspberry Pi

Assuming you have enough disk space ... just use "unzip", then "dd" to write the image to the SD card. More helpfully, follow this link down to the Linux section where the process is described in great detail. https://www.raspberrypi.org/documentation/installation/installing-images/README.md The Pi ...
by jahboater
Tue Jan 26, 2016 5:01 am
Forum: General discussion
Topic: Block size & lots of small files
Replies: 20
Views: 6255

Re: Block size & lots of small files

Is that with a 4GB SD card? ext4 defaults to one inode per 16 kilobytes so larger partitions have more inodes. For comparison, Raspbian Jessie's root file system on a 64GB card has about 3.7M inodes. Or the user may set any value during the format (mkfs.ext4) -N number-of-inodes Overrides the defau...
by jahboater
Mon Jan 25, 2016 6:59 pm
Forum: Beginners
Topic: cpu usage run 100%
Replies: 2
Views: 430

Re: cpu usage run 100%

Could you help me please? I do my project with raspberry pi , processing but I am facing a problem. when I run code, it show that cpu usage run 100%. My question is 1. Can I resolve problem (cpu usage run 100%) anyway? If I change SD card that can help me? or I have only one way to adapt my code? 2...
by jahboater
Mon Jan 25, 2016 12:19 pm
Forum: C/C++
Topic: How to cross-compile and debug a C program?
Replies: 8
Views: 2437

Re: How to corss-compile and debug a C program?

For debugging use "gdb" which is included with raspbian.

If there is no documentation (man pages) for gdb or gcc do:-

Code: Select all

sudo apt-get update
sudo apt-get install gcc-4.9-doc gdb-doc
by jahboater
Mon Jan 25, 2016 11:02 am
Forum: C/C++
Topic: How to cross-compile and debug a C program?
Replies: 8
Views: 2437

Re: How to corss-compile and debug a C program?

Time to compile a large single source file (not recommended - use make -j4 with multiple small files). 15,400 lines of code. 4GHz PC 1.63 sec 1GHz Pi2 20.08sec 1GHz Pi0 52.05 sec Of course the quad core Pi2 would do better with make -j which can compile multiple source files at once using all the co...
by jahboater
Mon Jan 25, 2016 10:45 am
Forum: General discussion
Topic: Block size & lots of small files
Replies: 20
Views: 6255

Re: Block size & lots of small files

The reason I used individual files rather than a large file(s) is that the packets need to be read out of the file one by one, sent to the server and then deleted. As I understand doing this requires you to read the whole file into memory read the first line, remove it and then write the whole file...
by jahboater
Mon Jan 25, 2016 10:15 am
Forum: Advanced users
Topic: Overclocking
Replies: 1125
Views: 605056

Re: Overclocking

I tried 550Mhz again this time with over_voltage_sdram=5 and it failed in memtester early on. I tried over_voltage_sdram=6 which also failed. For 500Mhz on a different Pi2, the overclock survived 11 hours of stress testing - which is a "result", that Pi was never stable with the old firmware. The sd...
by jahboater
Mon Jan 25, 2016 9:45 am
Forum: C/C++
Topic: How to cross-compile and debug a C program?
Replies: 8
Views: 2437

Re: How to corss-compile and debug a C program?

My purpose is to develop / debug on my computer, and do not keep the operation on Raspberry. Is there any particular reason why you want to develop the code on you PC? The Raspberry Pi is itself a highly capable "computer" easily able to develop / debug a small C program. Because the Pi is credit c...
by jahboater
Mon Jan 25, 2016 8:31 am
Forum: Beginners
Topic: Resistors and physical computing.
Replies: 6
Views: 1101

Re: Resistors and physical computing.

Google "ohms law" or see the wikipedia entry - its actually very simple.
by jahboater
Sun Jan 24, 2016 10:31 pm
Forum: Advanced users
Topic: Overclocking
Replies: 1125
Views: 605056

Re: Overclocking

Does sdram_freq=550 work for you? It didn't for me with the new firmware. memtester 800m and about six small cpu bound processes failed after about 20 mins. over_voltage=2 over_voltage_sdram=2 arm_freq=1000 core_freq=500 sdram_freq=550 That's on a cherry picked Pi2 with a heatsink on the sdram chip...
by jahboater
Sun Jan 24, 2016 12:51 am
Forum: C/C++
Topic: Creating Script to Log "top" Command Output
Replies: 8
Views: 1305

Re: Creating Script to Log "top" Command Output

Back in the early days of Linux I wrote a resource monitor in C that kept track of load level, network utilization, page rate and memory used. This involved reading files in proc In the really early days (UNIX), much more fun was to get the kernel symbol table, open /dev/kmem, find the process tabl...

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