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by jdb
Fri Mar 22, 2019 9:21 pm
Forum: Automation, sensing and robotics
Topic: electric dog collar based on radio waves
Replies: 13
Views: 223

Re: electric dog collar based on radio waves

Thank You guys for all the help , I'm almost finished the normal fence to them2400metres squares to give them freedom , but if You are not up to make my idea on raspberry IT gave me a brighter look on this problem. Thanks, If somebody Has some idea please do not hesitate Do not use Raspberry Pis to...
by jdb
Fri Mar 22, 2019 4:23 pm
Forum: General discussion
Topic: Sterilization of Pi
Replies: 14
Views: 462

Re: Sterilization of Pi

Never mind the stored charge (there won't be any after >10 seconds of power-off), what gas is being used? There are plastics/epoxies used in component encapsulation that may not play at all well with aggressive solvents.
by jdb
Mon Mar 04, 2019 1:28 pm
Forum: Off topic discussion
Topic: Is ARM doomed?
Replies: 179
Views: 6348

Re: Is ARM doomed?

In what way can the ARM be better implemented? What techniques would that improvement use that cannot also be used in a RISC V design? Ok I will bite and answer. The techniques would be the same for both ISA's to reach ideal performance of the ISA. The difference is that a single instruction (howev...
by jdb
Fri Feb 22, 2019 10:31 pm
Forum: General discussion
Topic: Why must the raspberrypi be so proprietary?
Replies: 44
Views: 1412

Re: Why must the raspberrypi be so proprietary?

LTolledo wrote:
Fri Feb 22, 2019 7:16 pm
I doubt the OP will be coming back to join the discussions here.....
Correct.
It's been 24 hours and OP hasn't replied to a thread that's got dozens of replies (including from RPTL employees)

Locked, trollbait detected.
by jdb
Fri Feb 22, 2019 1:09 pm
Forum: Advanced users
Topic: Raspberry Pi SRAM
Replies: 21
Views: 1131

Re: Raspberry Pi SRAM

If we're looking for hardware differentiability, then there's a set of well-known ones - the characterisation ring oscillators. BCM283x has several free-running oscillators scattered around the die that are primarily used for CPU AVS - as each chip has a different speed, we need to adjust turbo-mode...
by jdb
Thu Feb 21, 2019 8:41 pm
Forum: Advanced users
Topic: Analogue audio redux
Replies: 73
Views: 19314

Re: Analogue audio redux

The driver is specific to the onboard 3.5mm jack audio.
by jdb
Thu Feb 21, 2019 8:31 pm
Forum: Advanced users
Topic: Raspberry Pi SRAM
Replies: 21
Views: 1131

Re: Raspberry Pi SRAM

Yes, but is it direct mapped cache or fully associative or some level set associativity in between? What is the cache replacement policy? Depends on which RPi and which cache. For the RPi3's A53s the L1 I-caches are 2-way, the L1 D-caches are 4-way and the L2 cache is 16-way set associative. Replac...
by jdb
Tue Feb 19, 2019 2:28 pm
Forum: Off topic discussion
Topic: Is ARM doomed?
Replies: 179
Views: 6348

Re: Is ARM doomed?

Interestingly, for megacorps such as Apple and Qualcomm they have outgrown the ARM per-processor licensing model and gone straight for "architectural" licences where they get to design their own AARCH compatible cores. I would wager that economies of scale come into play here - if you're shipping 5 ...
by jdb
Mon Feb 18, 2019 4:24 pm
Forum: HATs and other add-ons
Topic: Does TV HAT support BBC Red Button using MHEG-5?
Replies: 5
Views: 827

Re: Does TV HAT support BBC Red Button using MHEG-5?

The TV hat works one layer down from MHEG-5. It's up to the video decode and presentation to parse overlays/subtitles/network information. There's no reason why it shouldn't work - it's all the same datastream.
by jdb
Mon Feb 18, 2019 4:22 pm
Forum: Off topic discussion
Topic: Is ARM doomed?
Replies: 179
Views: 6348

Re: Is ARM doomed?

fruitoftheloom wrote:
Mon Feb 18, 2019 1:51 pm

Poppycock and balderdash :roll:
If you don't have anything to say other than this inane comment, don't post.
by jdb
Sun Feb 17, 2019 6:48 pm
Forum: Off topic discussion
Topic: Finally found out why SD cards were so unreliable on early Pi
Replies: 6
Views: 765

Re: Finally found out why SD cards were so unreliable on early Pi

I wonder if he had a slip of the tongue and meant SDIO (not SPI) MMC controller. That would match. Interesting if so. Then again his notes say quite clearly SPI. SD cards can be accessed over SPI. It part of specification compliance - cards must implement this mode. Microcontrollers frequently use ...
by jdb
Fri Feb 15, 2019 2:56 pm
Forum: Off topic discussion
Topic: Order a special request Raspberry Pi :?:
Replies: 68
Views: 2847

Re: Order a special request Raspberry Pi :?:

To the OP: If the Raspberry Pi doesn't meet your requirements (32G RAM? Really?), I suggest buying something that does.
by jdb
Fri Feb 15, 2019 12:51 pm
Forum: Off topic discussion
Topic: Is ARM doomed?
Replies: 179
Views: 6348

Re: Is ARM doomed?

RISC-V displacing microcontroller-type cores (in-order, 1-wide issue, modest clockspeed) is very much happening - Western Digital are now using RISC-V cores in their storage controllers. ARM doesn't really have any feature differentiation in this segment, except for being widely supported in gcc/llv...
by jdb
Fri Feb 08, 2019 4:07 pm
Forum: General discussion
Topic: [RPI-3B+ USB interrupt issue] why there are so many interrupts from USB controller
Replies: 4
Views: 192

Re: [RPI-3B+ USB interrupt issue] why there are so many interrupts from USB controller

You are correct in stating that the frequency of interrupts does not decrease - the FIQ is used for two reasons 1) so that the general hard IRQ latency of Linux is avoided, as the USB hardware is very timing-sensitive and 2) so that the handler can be made as lightweight as possible. With Linux hand...
by jdb
Fri Feb 08, 2019 4:01 pm
Forum: General discussion
Topic: Pi 3A+ Schematic question
Replies: 6
Views: 281

Re: Pi 3A+ Schematic question

Missing from the 3B+ sheet but present on the 3A+ sheet is the arcane invocation "Make ADC traces accessible before shorting to GND" Also, I don't quite understand what AGND is for, since it doesn't appear anywhere other than round the PMIC, and not where I would have expected, at the audio subsyst...
by jdb
Fri Feb 08, 2019 3:13 pm
Forum: General discussion
Topic: [RPI-3B+ USB interrupt issue] why there are so many interrupts from USB controller
Replies: 4
Views: 192

Re: [RPI-3B+ USB interrupt issue] why there are so many interrupts from USB controller

From the boot log: [ 4.358325] dwc2 3f980000.usb: dwc2_check_params: Invalid parameter lpm=1 [ 4.365270] dwc2 3f980000.usb: dwc2_check_params: Invalid parameter lpm_clock_gating=1 [ 4.373351] dwc2 3f980000.usb: dwc2_check_params: Invalid parameter besl=1 [ 4.380368] dwc2 3f980000.usb: dwc2_check_par...
by jdb
Tue Feb 05, 2019 8:25 pm
Forum: General discussion
Topic: Physical port widths on B+
Replies: 21
Views: 551

Re: Physical port widths on B+

Given that the ports adhere to industry standards for the respective interfaces, how about looking up the documents for e.g. a USB or HDMI socket?
by jdb
Fri Feb 01, 2019 9:09 pm
Forum: Off topic discussion
Topic: Raspberry Pi SBC future ?
Replies: 12
Views: 1091

Re: Raspberry Pi SBC future ?

fruitoftheloom wrote:
Fri Feb 01, 2019 7:12 pm
How authentic is this Blog ??

https://www.tomshardware.co.uk/raspberr ... 59876.html
... it quotes Eben by name and the interviewer is the Editor-in-Chief of Tom's Hardware (a website I know from 20 years ago)?
What more do you want?
by jdb
Thu Jan 31, 2019 2:29 pm
Forum: General discussion
Topic: RISC-V
Replies: 96
Views: 4446

Re: RISC-V

For example, partial registers are an x86 (mis)feature that add complexity to out-of-order implementations. Massively variable instruction length (1 to 15 bytes, with prefix modifiers) makes superscalar x86 frontends larger and more power-hungry. Flags registers are handy, but also an implicit resu...
by jdb
Fri Jan 25, 2019 11:34 pm
Forum: General discussion
Topic: Power Supply - Radio Interference
Replies: 38
Views: 1245

Re: Power Supply - Radio Interference

Sounds like the non-official PSUs have some sort of voltage-leveling circuitry built into them, so any frequencies introduced from the outlet or transformer oscillator are cancelled out BEFORE entering the Pi. Try connecting a capacitor around the 470uf range to the 5v and GND GPIO pins. The capaci...
by jdb
Fri Jan 25, 2019 3:37 pm
Forum: General discussion
Topic: Power Supply - Radio Interference
Replies: 38
Views: 1245

Re: Power Supply - Radio Interference

There may be no ground connection but the output voltage is weakly referenced to line/neutral via ~2nF Y-class capacitor - it provides a return path for any switching-frequency currents that couple across the transformer. If the AM receiver is presenting a lower impedance via its own ground connecti...
by jdb
Fri Jan 25, 2019 2:27 pm
Forum: General discussion
Topic: SD Card speed - Pi limitation ?
Replies: 20
Views: 734

Re: SD Card speed - Pi limitation ?

The overall "bus" speed of the SD card slot is approx. 23MB/s read or write. With the root filesystem on an SD card, the critical parameter for performance isn't sequential read or write speed (which is what many of these basic testers give you numbers for) but random 4k read/write performance. Rand...
by jdb
Fri Jan 25, 2019 1:54 pm
Forum: Advanced users
Topic: Analogue audio redux
Replies: 73
Views: 19314

Re: Analogue audio redux

Is the content 1080i interlaced? If so, then adaptive deinterlace is probably being used.
Can you try setting the deinterlacer to "line double (hw)"?
by jdb
Thu Jan 24, 2019 8:21 pm
Forum: Advanced users
Topic: Analogue audio redux
Replies: 73
Views: 19314

Re: Analogue audio redux

What are you playing over the analogue audio jack? What command are you using to start playback?

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