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by okenido
Mon Oct 18, 2021 3:19 pm
Forum: General discussion
Topic: Do we love the 40-pin header? Is there something more desireable?
Replies: 33
Views: 1467

Re: Do we love the 40-pin header? Is there something more desireable?

An IDE cable will fit the full header allowing for re-use of old cables DO NOT use IDE cables with your Raspberry PI, that will kill it. IDE cables have several wires shorted together by design inside them. I posted about how stupid that design was a long time ago. i personnally thing that was Stup...
by okenido
Sat Feb 13, 2021 11:13 am
Forum: General discussion
Topic: Killed a Pi with overvoltage, and now it works again ?
Replies: 8
Views: 586

Re: Killed a Pi with overvoltage, and now it works again ?

I'm looking at the schematics : https://www.raspberrypi.org/documentation/hardware/raspberrypi/schematics/rpi_SCH_3b_1p2_reduced.pdf D5 transil/zener diode is between +5V and GND, that may have clamped the overvoltage and overheated a bit Other that that 5V directly goes into PAM2306AYPKE so maybe i...
by okenido
Sat Feb 13, 2021 1:20 am
Forum: General discussion
Topic: Killed a Pi with overvoltage, and now it works again ?
Replies: 8
Views: 586

Killed a Pi with overvoltage, and now it works again ?

Hi, I'm designing products with Raspberry Pi 3B, V1.2 I power it directly via GPIO, my main board which powers the Pi was faulty, it sent by accident 8V instead of 5V during a few seconds. After that the Pi was dead, only red LED, no green LED, no activity, won't read anything from the SD card nor t...
by okenido
Mon Oct 05, 2020 10:24 pm
Forum: Beginners
Topic: 4, 8GB RAM or no Pi at all for Firefox browsing ?
Replies: 30
Views: 3299

Re: 4, 8GB RAM or no Pi at all for Firefox browsing ?

I don't think it's even close to 1/4 of the power of a modern x86 in single thread. 1/10 was already optimistic. It's not a bad CPU but it's < 5W power consumption and made with quite a large process (28 nm ?), ARM is efficient but not magic :D SSE ARM equivalent (NEON) works pretty well tho. I can ...
by okenido
Mon Oct 05, 2020 1:37 pm
Forum: Beginners
Topic: 4, 8GB RAM or no Pi at all for Firefox browsing ?
Replies: 30
Views: 3299

Re: 4, 8GB RAM or no Pi at all for Firefox browsing ?

Which is silly, you get the same amount of RAM as a desktop with less than 10% of the CPU performance. Not balanced at all
by okenido
Tue Sep 29, 2020 1:29 pm
Forum: Official Display
Topic: Wrong colors on some 7inch displays
Replies: 7
Views: 822

Re: Wrong colors on some 7inch displays

Not sure that is covered by RMA as the screen in working
by okenido
Mon Sep 28, 2020 9:27 pm
Forum: Official Display
Topic: 2 KHz whistling electronics of 7" LCD's
Replies: 4
Views: 1039

Re: 2 KHz whistling electronics of 7" LCD's

I haven't noticed that on mines. Did you tried several brightness settings ? It could be a power supply thing - LCD circuits making noise with some supplies and not others
by okenido
Mon Sep 28, 2020 2:48 pm
Forum: Official Display
Topic: Wrong colors on some 7inch displays
Replies: 7
Views: 822

Wrong colors on some 7inch displays

Hi, I use the official 7 inch screen a lot, bought approx 200 units. Out of 200, 2 of them have very pronounced color balance issues. It seems to be on the blue channel on both, when Blue=31 (max intensity in RGB 565) the color is good, but for lower values the intensity seems to decrease too quickl...
by okenido
Thu Jun 11, 2020 11:19 am
Forum: Bare metal, Assembly language
Topic: System freezes - howto diagnose
Replies: 8
Views: 1475

Re: System freezes - howto diagnose

I don't know specifically for your case but in my bare metal apps I had random crashes with IRQ/FIQ when I didnt saved/restored floating point registers in the interrupt handler (depends if you use these...).

What happens if you add some timeout to your while loop ? Does the program keeps running ?
by okenido
Sat Jun 06, 2020 12:13 am
Forum: General discussion
Topic: Fail-safe firmware upgrades
Replies: 16
Views: 859

Re: Fail-safe firmware upgrades

Do you use FatFS like me ? It seems f_close() does the sync so it's not needed to call it manually
by okenido
Fri Jun 05, 2020 11:52 pm
Forum: General discussion
Topic: Fail-safe firmware upgrades
Replies: 16
Views: 859

Re: Fail-safe firmware upgrades

I fear there is no 100% fail-safe software method against the SD card doing its wear leveling. Anyway for the files going with the firmware I replaced the direct overwrite with a temporary copy + move, it's already way better as the critical time window where things can go wrong is considerably redu...
by okenido
Fri Jun 05, 2020 4:48 pm
Forum: General discussion
Topic: Fail-safe firmware upgrades
Replies: 16
Views: 859

Re: Fail-safe firmware upgrades

I'm only changing one byte from the file, leaving its size untouched so it should be fine to prevent corruptions (eg. kernel8.img => kernel9.img) However I'm not sure how to deal with the problem regarding the firmware file itself. Maybe I can simply add lots of zero bytes at the end, providing enou...
by okenido
Fri Jun 05, 2020 2:28 pm
Forum: General discussion
Topic: Fail-safe firmware upgrades
Replies: 16
Views: 859

Re: Fail-safe firmware upgrades

* it's kernel parameter, not start_file
by okenido
Fri Jun 05, 2020 2:09 pm
Forum: General discussion
Topic: Fail-safe firmware upgrades
Replies: 16
Views: 859

Re: Fail-safe firmware upgrades

Interesting I'll check that too - I was simply thinking about swapping between the two firmware files, then updating config.txt programatically after the write is completed, so any power loss simply leave the system working on the already existing firmware
by okenido
Fri Jun 05, 2020 1:22 pm
Forum: General discussion
Topic: Fail-safe firmware upgrades
Replies: 16
Views: 859

Re: Fail-safe firmware upgrades

It seems start_file in config.txt would simply do what I need, i'll try that thanks
by okenido
Fri Jun 05, 2020 1:16 pm
Forum: General discussion
Topic: Fail-safe firmware upgrades
Replies: 16
Views: 859

Re: Fail-safe firmware upgrades

I wasn't very clear sorry, the RPI isn't bricked but the device embedding it is (unless you tell the user to open his device which isn't very practical)
by okenido
Fri Jun 05, 2020 12:49 pm
Forum: General discussion
Topic: Fail-safe firmware upgrades
Replies: 16
Views: 859

Fail-safe firmware upgrades

Hi My RPI3B+ has a custom made firmware (with bare metal code), and the firmware can be upgraded via USB. When the upgrade happens, the kernel8.img file is copied from USB to the SD card. If a power loss occurs at this moment, the file can be corrupted and the device bricked. A common method to make...
by okenido
Wed May 13, 2020 4:52 pm
Forum: Bare metal, Assembly language
Topic: RPI3B+ I would like to make a game
Replies: 5
Views: 1238

Re: RPI3B+ I would like to make a game

Initializing and reading from the SD card is quite a complicated task.
I'd suggest using a bare metal library first (like Circle) and looking how things are done, then you can decide to go the full assembly way or stay quite close to the metal but with a library.
by okenido
Sat May 09, 2020 7:08 pm
Forum: General discussion
Topic: Get your Pi to fight COVID-19
Replies: 194
Views: 24684

Re: Get your Pi to fight COVID-19

Covid is bad for humanity, but good for the planet
:o :shock: :? :P
by okenido
Sat May 09, 2020 3:13 pm
Forum: General discussion
Topic: GPU minimum frequency ? Safe undervoltage ?
Replies: 0
Views: 249

GPU minimum frequency ? Safe undervoltage ?

I'm using the raspberry with bare metal code, using a screen but doing only software rendering to the framebuffer. I'm trying to reduce the SoC heat as much as possible, so I underclocked the GPU and I get a few mW saving with everything still working. In config.txt : h264_freq_min=100 isp_freq_min=...
by okenido
Wed Apr 29, 2020 3:15 pm
Forum: Bare metal, Assembly language
Topic: Bare metal UART w/FIQ stops working
Replies: 3
Views: 659

Re: Bare metal UART w/FIQ stops working

Nailed it! I had a parallel processing that was modifying a variable that could be potentially used by another core. When it was modified at the wrong timing it accessed an array with an index of -1. That was causing the exception. Damn it sounds so dumb, but the symptoms made it super hard to find ...
by okenido
Wed Apr 29, 2020 12:36 pm
Forum: Bare metal, Assembly language
Topic: Bare metal UART w/FIQ stops working
Replies: 3
Views: 659

Re: Bare metal UART w/FIQ stops working

Thanks, I was able to somewhat locate the error because it triggered an exception (which was silently ignored because I had everything setup for a release) which in turn disabled the FIQ (found in Circle's exception handler). I have some code that is writing to an invalid memory location. It should ...
by okenido
Wed Apr 29, 2020 12:11 am
Forum: Bare metal, Assembly language
Topic: Bare metal UART w/FIQ stops working
Replies: 3
Views: 659

Bare metal UART w/FIQ stops working

I'm using the bare metal library Circle (https://github.com/rsta2/circle) for my project and i'm facing a weird problem. I have UART0 setup in FIQ mode to receive some serial data, with the provided class CSerialDevice which works fine in a minimal example (https://github.com/rsta2/circle/blob/maste...
by okenido
Wed Mar 04, 2020 11:56 am
Forum: Official Display
Topic: New Display - Cursor Jumps and Clicks all over the place
Replies: 25
Views: 15901

Re: New Display - Cursor Jumps and Clicks all over the place

I'm designing a product using the 7 inch display and i'm quite worried about this issue. My prototypes exhibited the same random clicks all over the place, sometimes after a few months of use. I'm not sure it's a product's fault since I damaged the corners of most of my prototypes, corners of this i...
by okenido
Mon Aug 12, 2019 2:04 pm
Forum: General discussion
Topic: Why moving to 64bit?
Replies: 273
Views: 54731

Re: Why moving to 64bit?

I think 64 bit is mostly worth it, you get double the NEON registers, that can improve performance drastically if the software is written to take advantage of it.
However an app that is constrained by memory bandwidth limits and doing zillions of pointer manipulation will probably suffer

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