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by plugwash
Tue Nov 16, 2021 5:28 am
Forum: C/C++
Topic: Why do I keep reading the word 'Atomic' everywhere these days!?!
Replies: 19
Views: 770

Re: Why do I keep reading the word 'Atomic' everywhere these days!?!

Heater wrote:
Mon Nov 15, 2021 4:32 am
It does not. It cannot.
At least on arm linux for architecture versions that don't gaurantee atomics, it punts the problem to the kernel.

The kernel in turn is expected to know how to deal with the particular arm core(s) that the target hardware has.
by plugwash
Wed Nov 10, 2021 8:43 pm
Forum: C/C++
Topic: Why do I keep reading the word 'Atomic' everywhere these days!?!
Replies: 19
Views: 770

Re: Why do I keep reading the word 'Atomic' everywhere these days!?!

atomic in general means something that happens or at least appears to happen in a single step without any intermediate states being visible. Locking can be one tool towards achiving that goal but it's not the only approach and locking alone may not be sufficient in more complex cases where some of t...
by plugwash
Mon Sep 13, 2021 11:36 am
Forum: Raspberry Pi OS
Topic: legacy materials moving from archive.raspbian.org to legacy.raspbian.org
Replies: 12
Views: 16327

Re: legacy materials moving from archive.raspbian.org to legacy.raspbian.org

'Any references to archive.raspbian.org mirrordirector.raspbian.org or raspbian.raspberrypi.org should be replaced with legacy.raspbian.org archive.raspberrypi.org should not be changed, that is the repo run by raspberry pi foundation/trading rather than the raspbian project. Note that there will be...
by plugwash
Mon Aug 23, 2021 2:04 pm
Forum: Raspberry Pi OS
Topic: legacy materials moving from archive.raspbian.org to legacy.raspbian.org
Replies: 12
Views: 16327

Re: legacy materials moving from archive.raspbian.org to legacy.raspbian.org

jessie/jessie-staging have now been removed from the regular mirrors.
by plugwash
Wed Jun 02, 2021 1:21 am
Forum: Raspberry Pi OS
Topic: Kano OS/Stretch on Pi 4: Is It Possible?
Replies: 13
Views: 2114

Re: Kano OS/Stretch on Pi 4: Is It Possible?

Personally I'd suggest trying copying the latest firmware and kernels to the boot partition and the modules to the relavent location on the root partition, booting it up and seeing how far you get.

3D graphics probablly won't work, dunno if the Kano stuff needs that.
by plugwash
Thu Apr 15, 2021 7:59 pm
Forum: Raspberry Pi OS
Topic: legacy materials moving from archive.raspbian.org to legacy.raspbian.org
Replies: 12
Views: 16327

Re: legacy materials moving from archive.raspbian.org to legacy.raspbian.org

two years on and i've now added jessie/jessie-staging to legacy.raspbian.org . It will be removed from the regular mirrors in due course.
by plugwash
Wed Apr 14, 2021 4:51 pm
Forum: Raspberry Pi OS
Topic: How do I upgrade Buster to PHP 8.0 on a ARMv6 Raspberry Pi arch
Replies: 14
Views: 2137

Re: How do I upgrade Buster to PHP 8.0 on a ARMv6 Raspberry Pi arch

You should be able to download the source packages and rebuild them on raspbian. Do we have to rebuild it on a ARMv6 RPI or is a virtual machine normally used for this? As long as you build it in a raspbian environment you should be ok, even if the hardware is a newer version of arm (or even an x86...
by plugwash
Thu Apr 08, 2021 5:08 pm
Forum: General discussion
Topic: All mags from Pi Press on Bookshelf?
Replies: 2
Views: 289

Re: All mags from Pi Press on Bookshelf?

This post is my personal analysis of the situation, I don't have any insider info on this. The three titles I see not present are "custom PC", "Digital SLR photography" and "hello world". custom PC and Digital SLR photography were bought by raspberry pi from dennis publ...
by plugwash
Tue Mar 30, 2021 8:35 pm
Forum: Raspberry Pi OS
Topic: new pigpio packages for testing
Replies: 14
Views: 4910

Re: new pigpio packages for testing

Thanks serge, it probablly makes more sense for this to go via the rpt repo anyway.

Also good spot on the python2 package, The packages were based on the ones I had prepared for bullseye, where python 2 is (mostly) going away.
by plugwash
Wed Mar 24, 2021 4:44 pm
Forum: C/C++
Topic: pigpiod says that Pi400 does not appear to be a raspberry pi
Replies: 30
Views: 3510

Re: pigpiod says that Pi400 does not appear to be a raspberry pi

I created an updated package and called for testing a month or so but got little response. I'd like some more feedback before I push it over to the main repo.

viewtopic.php?f=66&t=304568&p=1822863#p1822863
by plugwash
Thu Mar 11, 2021 3:18 am
Forum: C/C++
Topic: some strange effekts with HTTPS "git clone"
Replies: 16
Views: 1311

Re: some strange effekts with HTTPS "git clone"

Ultimately, unless you can come up with a reproduction of the issue that only involves publicly accessible resources, it's going to be rather difficult for anyone (other than possiblly bitbucket support) to provide any real help on the matter.
by plugwash
Wed Mar 10, 2021 2:51 pm
Forum: C/C++
Topic: some strange effekts with HTTPS "git clone"
Replies: 16
Views: 1311

Re: some strange effekts with HTTPS "git clone"

libcurl can be built against several different TLS libraries. Debian supplies builds of libcurl built against three different SSL libraries, openssl, gnutls and mozilla nss. Debian chooses, for license reasons to build git against the gnutls build of libcurl. You can see "libcurl3-gnutls" ...
by plugwash
Thu Mar 04, 2021 8:14 pm
Forum: Raspberry Pi OS
Topic: How do I upgrade Buster to PHP 8.0 on a ARMv6 Raspberry Pi arch
Replies: 14
Views: 2137

Re: How do I upgrade Buster to PHP 8.0 on a ARMv6 Raspberry Pi arch

You should be able to download the source packages and rebuild them on raspbian.
by plugwash
Tue Feb 23, 2021 5:45 am
Forum: C/C++
Topic: simple examples for C/C++ spi communications using spidev
Replies: 16
Views: 5462

Re: simple examples for C/C++ spi communications using spidev

I haven't bothered to find out precisely why as it's outside my control. I'd guess the layoff between userland and the kernel is soaking up the time. pigpio stays in userland for the transaction. SPI_IOC_MESSAGE does allow you to send more than one transaction at a time, I wonder how this impacts o...
by plugwash
Sat Feb 20, 2021 2:14 am
Forum: C/C++
Topic: whats are the best SPI libraries in 2021
Replies: 9
Views: 997

Re: whats are the best SPI libraries in 2021

My recommendation, unless you have very specific requirements they can't cover, is to use the kernel's spidev support, it's supported on all Pi models and can also be used on a number of other boards (my project for my dayjob is using it on a Jetson Nano) and i don't think it's likely to go away any...
by plugwash
Sat Feb 20, 2021 1:42 am
Forum: Advanced users
Topic: Maximum current available from +5V on GPIO connector?
Replies: 6
Views: 526

Re: Maximum current available from +5V on GPIO connector?

The 5V pin on the main GPIO header is tied direct to the main 5V rail. So how much current you can draw from it will depend on what power supply you are using, what Pi model you have and what else is drawing power.
by plugwash
Fri Feb 19, 2021 5:07 am
Forum: Raspberry Pi OS
Topic: pigpio and 64 bit
Replies: 2
Views: 634

Re: pigpio and 64 bit

I've prepared a package of the latest pigpio at http://plugwash.raspbian.org/pigpio/ there are no arm64 binaries there right now but you should be able to build it from the source package. If the results of my general call for testing of the new package are positive I will add it to the main raspbia...
by plugwash
Fri Feb 19, 2021 5:06 am
Forum: Raspberry Pi OS
Topic: new pigpio packages for testing
Replies: 14
Views: 4910

new pigpio packages for testing

I've created an updated pigpio package, I have reports that basic tests work but i'd like to get confirmation that i'm not going to horriblly break anything before I push it into the main raspbian buster repository.

The package is available from http://plugwash.raspbian.org/pigpio/ please test it.
by plugwash
Thu Feb 18, 2021 1:25 am
Forum: MicroPython
Topic: How To : Add C Extensions to Pico MicroPython
Replies: 17
Views: 2276

Re: How To : Add C Extensions to Pico MicroPython

kilograham wrote:
Sat Feb 06, 2021 12:02 am
busy_wait_us() can be used in place of sleep_us() with the obvious distinction.
Can it be safely called from code that runs with XIP non-funcational?
by plugwash
Fri Feb 05, 2021 11:14 pm
Forum: General discussion
Topic: Do I need to remove fake-hwclock if I use an RTC chip?
Replies: 10
Views: 1884

Re: Do I need to remove fake-hwclock if I use an RTC chip?

fake-hwclock in it's default configuration will only move the time forwards not backwards. So it won't generally interfere with proper timekeeping soloutions.
by plugwash
Wed Feb 03, 2021 12:49 pm
Forum: General
Topic: RP2040
Replies: 29
Views: 2025

Re: RP2040

W. H. Heydt wrote:
Mon Feb 01, 2021 9:43 pm
I really don't envy the person having to make those forecasts.
I personally feel that they make life harder for themselves by refusing to pre-announce stuff or take pre-orders.
by plugwash
Tue Feb 02, 2021 5:26 am
Forum: MicroPython
Topic: Is there any comprehensive documentation for the pico_python_sdk?
Replies: 6
Views: 1335

Re: Is there any comprehensive documentation for the pico_python_sdk?

The intent of that equation is to avoid leaving a big gap at the top end of the range, instead using a mixture of steps of 16 and steps of 17.
by plugwash
Mon Feb 01, 2021 10:42 pm
Forum: General discussion
Topic: How to upgrade an apt package
Replies: 9
Views: 739

Re: How to upgrade an apt package

The big thing that needs to happen is that raspberry Pi need to bring their pile of modifications/programs/etc that they build on top of debian/raspbian forward from Buster to Bullseye and start testing the result. Traditionally I have advised them to start doing this around the time of the freeze s...
by plugwash
Mon Feb 01, 2021 8:29 pm
Forum: Troubleshooting
Topic: PI 3b+ Under-voltage detected... with a (supposedly) proper power supply
Replies: 4
Views: 292

Re: PI 3b+ Under-voltage detected... with a (supposedly) proper power supply

Stuff fails, stuff from dubious vendors fails more often than stuff from reputable vendors. Power supplies often seem to fail in ways that reduce the voltage/current available rather than failing outright. Generally as voltage falls on the Pi, the perhiperals tend to start behaving erratically befor...
by plugwash
Mon Feb 01, 2021 6:40 pm
Forum: C/C++
Topic: understanding "string" class
Replies: 10
Views: 1062

Re: understanding "string" class

It is possible to access global variables by name in C on linux. #define _GNU_SOURCE #include <dlfcn.h> #include <stdio.h> int foo = 12345; int main() { char * varname = "foo"; int *p = (int *)(dlsym(RTLD_DEFAULT,varname)); if (p) { printf("%d\n",*p); } else { printf("var no...

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