Go to advanced search

by jdb
Tue Jan 22, 2019 4:50 pm
Forum: General discussion
Topic: Power Supply - Radio Interference
Replies: 11
Views: 235

Re: Power Supply - Radio Interference

What AM band is your receiver tuned to? Does the buzzing change if you put audio_pwm_mode=1 in /boot/config.txt? I see that the buzz disappears with different PSUs, but I want to rule out an interaction between how we're driving analogue audio and any ground noise (as the official PSU uses a "floati...
by jdb
Sat Jan 19, 2019 12:08 am
Forum: Advanced users
Topic: Virtual com port drivers?
Replies: 8
Views: 244

Re: Virtual com port drivers?

Do you have any USB-serial devices plugged in to your Pi?
by jdb
Fri Jan 18, 2019 3:50 pm
Forum: General discussion
Topic: new to soldering - safety questions, etc.
Replies: 46
Views: 894

Re: new to soldering - safety questions, etc.

sharpen it after every use. This I'd strongly disagree with. Most soldering iron bits have a protective coating. Sharpening them will remove this coating and expose the unprotected core which will rapidly degrade through use. Correct, soldering irons typically have iron-plated tips with a copper or...
by jdb
Thu Jan 17, 2019 10:03 pm
Forum: Advanced users
Topic: Virtual com port drivers?
Replies: 8
Views: 244

Re: Virtual com port drivers?

COM ports are a windows construct. USB-serial devices appear as tty's (terminal devices) as /dev/ttyUSB0 - /dev/ttyUSBx. You can access them through various file stream utilities (i.e. echo "blah" > /dev/ttyUSB0 results in blah being transmitted on the wire) or via system calls in your own programs....
by jdb
Thu Jan 17, 2019 9:55 pm
Forum: HATs and other add-ons
Topic: Interface boards for Quadrature Encoders
Replies: 3
Views: 250

Re: Interface boards for Quadrature Encoders

The chip is accessed through a command/address bus with chip-enable and R/W# signalling. There's the SMI peripheral on the Pi which could be used to interface to this. It would require careful reading of the timings and you will have to munge the address pins on to the various "register select" pins...
by jdb
Wed Jan 16, 2019 11:17 pm
Forum: General discussion
Topic: Pi 3b+ lost Capacitor on PCB
Replies: 16
Views: 882

Re: Pi 3b+ lost Capacitor on PCB

... they're just small decoupling caps that were found to be unnecessary and therefore removed from the BOM. There are also at least four around the PMIC also removed. I wonder how it's determined that they're unnecessary. Does someone take a representative sample of boards - say, a thousand - and ...
by jdb
Wed Jan 16, 2019 11:09 pm
Forum: Advanced users
Topic: Raspberry PI cold boot attack protected / Zero out RAM after boot?
Replies: 71
Views: 2371

Re: Raspberry PI cold boot attack protected / Zero out RAM after boot?

I think this thread is done. If you're wanting a "secure" device then there are many out there on sale that tout various security features - writing 0s to SDRAM on boot is certainly to be among them. The Pi is most definitely NOT a secure hardware device in the common sense of the word. Users wantin...
by jdb
Wed Jan 16, 2019 4:55 pm
Forum: Advanced users
Topic: Audio HISS: disable_audio_dither or audio_pwm_mode???
Replies: 6
Views: 2351

Re: Audio HISS: disable_audio_dither or audio_pwm_mode???

There should be no background hiss with audio_pwm_mode=2 (which is the default on Raspbian). disable_audio_dither will have no effect if audio_pwm_mode=2 is set. If you do have background noise when playing silence then there's a list of things that need checking: - If the background noise occurs im...
by jdb
Wed Jan 16, 2019 4:43 pm
Forum: Advanced users
Topic: Raspberry PI cold boot attack protected / Zero out RAM after boot?
Replies: 71
Views: 2371

Re: Raspberry PI cold boot attack protected / Zero out RAM after boot?

I suspect the added sales would take the digits up both hands and possibly one foot. Simply not high enough demand to do it. There is no 'massive profit' here. Lets say we change the bootloader in the SoC to zero RAM on startup. However, we make a mistake that get through simulation, and it stops t...
by jdb
Tue Jan 08, 2019 2:33 pm
Forum: General discussion
Topic: Using RPI with camera below 0 Celsius?
Replies: 24
Views: 505

Re: Using RPI with camera below 0 Celsius?

Condensation kills electronics, not subzero temperatures.

Was the Pi in an airtight enclosure?
by jdb
Sat Dec 22, 2018 9:33 pm
Forum: HATs and other add-ons
Topic: Choppy replay with TV uHat on pi zero w
Replies: 18
Views: 1746

Re: Choppy replay with TV uHat on pi zero w

One thing worth considering is the quality of the coaxial cable you are using to connect the antenna to the TV HAT. You have a very weak signal from a distant transmitter and a strong signal from a local transmitter. Though the frequencies of each are quite different, the TV HAT doesn't have bandpas...
by jdb
Tue Dec 11, 2018 10:41 pm
Forum: General discussion
Topic: Questionable actors
Replies: 3
Views: 256

Re: Questionable actors

I have no idea what this thread is supposed to accomplish other than encouraging flamewars and concern trolling.
Locked.
by jdb
Fri Nov 30, 2018 3:54 pm
Forum: Advanced users
Topic: f2fs : why not distribution with root fs as f2fs
Replies: 14
Views: 1060

Re: f2fs : why not distribution with root fs as f2fs

One point worth considering is that SD card manufacturers may be specifically optimising their FTL behaviours for workloads like ext4 and FAT - small in-place writes for metadata, arbitrary linear writes of file data. F2FS will have a completely different access pattern, namely avoiding repeated wri...
by jdb
Thu Nov 29, 2018 10:29 pm
Forum: General discussion
Topic: High Wattage Remote Relay
Replies: 9
Views: 222

Re: High Wattage Remote Relay

1500W of what? Lighting? Motors? Heater elements?
What's the duty cycle - 10 times in 15 minutes or is it going to switch some production line machinery that's operated hundreds of times per hour?
by jdb
Tue Nov 27, 2018 3:12 pm
Forum: General discussion
Topic: Flyback Diodes - Solenoid Valves
Replies: 9
Views: 349

Re: Flyback Diodes - Solenoid Valves

I'm assuming that this is a low-voltage DC solenoid (24Vdc). Two points of note from someone who used to fix systems using electromechanical components: Adding a snubber across the solenoid coil is the best method of protecting the control relay contacts. A snubber can either be a diode, RC filter o...
by jdb
Mon Nov 19, 2018 1:18 pm
Forum: Off topic discussion
Topic: So plan for Pi4 is already set in stone. What's in it?
Replies: 2
Views: 1370

Re: So plan for Pi4 is already set in stone. What's in it?

The sandwich dispenser and unicorn bridle are proving somewhat difficult to integrate. Joking aside, yes we have plans for a Pi4. Why wouldn't we? Moore's law is not yet exhausted and there are existing smaller process nodes, meaning there's scope for innovation and improvement at the same target pr...
by jdb
Thu Nov 01, 2018 1:08 pm
Forum: HATs and other add-ons
Topic: TV Hat - HD
Replies: 14
Views: 717

Re: TV Hat - HD

In theory the network information table (NIT) should provide details of the frequencies/muxes on the transmitter in question. It's odd that successfully tuning to an SD signal doesn't discover the T2 multiplexes - are they considered separate networks?
by jdb
Fri Oct 19, 2018 9:39 am
Forum: Off topic discussion
Topic: Add Analog to Digital pins to the pi
Replies: 14
Views: 2459

Re: Add Analog to Digital pins to the pi

Or what about >3MHz speeds for Video? :roll: :shock: In any case the current silicon process used for the SoC probably doesn't support analog circuitry (except perhaps for some switching supply logic, The previous PI's used an voltage controlled supply for the core, but probably that is done with d...
by jdb
Fri Oct 12, 2018 1:44 pm
Forum: General discussion
Topic: A2 app performance class SD cards
Replies: 11
Views: 1064

Re: A2 app performance class SD cards

+1 for App-class cards. The A1 random-read performance was often 2-3x our recommended NOOBS cards, but with a price premium.
A2 looks like a welcome bump to the critical parameter - random read IOPS.
by jdb
Thu Sep 20, 2018 5:29 pm
Forum: Troubleshooting
Topic: The USB power appeal
Replies: 43
Views: 3064

Re: The USB power appeal

Thousands of the RPi users are forced to do silly workarounds like this: https://i.stack.imgur.com/j7WBo.jpg to have their RPis working. Please provide evidence to support the claim that "thousands" of Raspberry Pi users have had to modify their boards. Also, what are the symptoms of the alleged is...
by jdb
Wed Sep 19, 2018 7:29 pm
Forum: General discussion
Topic: CB beacon out of raspberry pi
Replies: 9
Views: 551

Re: CB beacon out of raspberry pi

CB does not require license and i must prove you wrong RPi CAN BE USED as radio transmitter and i have passive filters And how will you ensure that the "passive filters" sufficiently filter harmonic emissions? Are you going to test your modified Pi in an anechoic chamber to make sure it won't leak ...
by jdb
Tue Sep 11, 2018 9:37 pm
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 319
Views: 56971

Re: PoE HAT - USB Ports not working - over-current

Thanks for interesting answers, tests and debate regarding power between the 2 sources. About the original issue of the PoE HAT, the engineering suggest some RPI 3B+ hardware are not impacted: one of the two brands of USB current limiting switch -> Is it possible to identify the component (software...
by jdb
Wed Sep 05, 2018 7:40 pm
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 319
Views: 56971

Re: PoE HAT - USB Ports not working - over-current

Please note: modifying your PoE HAT will obviously invalidate any warranty claim. It is however very useful that people are experimenting as it gives us more information to work with. We have managed to replicate the issue in a controlled environment (i.e. in the lab with programmable loads on the U...
by jdb
Tue Sep 04, 2018 10:34 pm
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 319
Views: 56971

Re: PoE HAT - USB Ports not working - over-current

If it doesn't work without a fudge then it's more expensive but more of a fudge than a cheap POE splitter, I wanted it as a neater alternative but as it's now turned out to have significant disadvantages over a POE splitter and no real advantages, I can't see any reason to keep it or recommend it. ...
by jdb
Tue Sep 04, 2018 9:25 pm
Forum: HATs and other add-ons
Topic: PoE HAT - USB Ports not working - over-current (FIXED - New Hardware Release)
Replies: 319
Views: 56971

Re: PoE HAT - USB Ports not working - over-current

Personally I don't regard this as a fix, so will be sending my hats back as faulty for a refund when I get back from this work trip and will go back to using cheap splitters at a fraction of the price but without the reliability problems. I'm surprised something this bad got released. Surely, the i...

Go to advanced search