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by Milliways
Wed Jul 01, 2020 7:31 am
Forum: Beginners
Topic: Problem measuring capacitor discharge time using GPIO pins
Replies: 7
Views: 227

Re: Problem measuring capacitor discharge time using GPIO pins

Similar circuits are used to measure capacitance (with relatively low precision), but you have deliberately nobbled yours by using 2 resistors. I can't imagine why you included the resistor in parallel. It will also take an age to discharge! Effectively you are charging from 1.65V via 500kΩ. The GPI...
by Milliways
Tue Jun 09, 2020 12:38 am
Forum: General discussion
Topic: Question to Raspberry Pi Foundation
Replies: 44
Views: 2029

Re: Question to Raspberry Pi Foundation

Not sure of that, but certainly the issue seen on the 3B+ where shorting the 3.3v and the 5v pins could blowup the PMIC. That's what I was talking about, and presumably what the OP was talking about. Note, we never regarded this as a fault (shorting pins is clearly a user error), so improving the r...
by Milliways
Sun Jun 07, 2020 2:02 am
Forum: Automation, sensing and robotics
Topic: [SOLVED] LM2596 buck converter to Pi 4 USB C
Replies: 6
Views: 360

Re: LM2596 buck converter to Pi 4 USB C

I am trying to wire a LM2596 buck converter to go from 24v down to the pi 4's 5v and I can't figure out how. I currently have a USB type C to USB A cable stripped (cut off the USB A) but I can't figure out which wires to use. Any advice/alternative methods to try? You need: 1. A multimeter 2. Knowl...
by Milliways
Mon Jun 01, 2020 1:38 am
Forum: Other programming languages
Topic: BASH script to check for Pi hardware and/or Raspbian
Replies: 13
Views: 8675

Re: BASH script to check for Pi hardware and/or Raspbian

Code: Select all

cat /proc/device-tree/model
should report model, which is easily parsed.


I use the following script to display useful info about Pi - it should work on most Linux OS (although some Raspbian specific entries don't work)
about
by Milliways
Sun May 31, 2020 2:15 am
Forum: Beginners
Topic: How to make menu button show up? [SOLVED]
Replies: 5
Views: 238

Re: How to make menu button work?

The icon field should be: [start-here] Without brackets! So it looks like Menu lo longer accepts full paths to images? Strange. Since I'm using a custom icon theme, it took me a bit of work to copy the rpi-logo files from PiXflat into the selected icon theme folder. Anyway, thank you kltricks for t...
by Milliways
Sun May 31, 2020 2:00 am
Forum: Beginners
Topic: How to make menu button show up? [SOLVED]
Replies: 5
Views: 238

Re: How to make menu button work?

Run the following (as root) #!/bin/bash cp /usr/share/icons/HighContrast/16x16/places/start-here.png /usr/share/icons/hicolor/16x16/apps/start-here.png cp /usr/share/icons/HighContrast/22x22/places/start-here.png /usr/share/icons/hicolor/22x22/apps/start-here.png cp /usr/share/icons/HighContrast/24x...
by Milliways
Fri May 01, 2020 2:52 am
Forum: General discussion
Topic: vcgencmd uses an APOSTROPHE to indicate temperature
Replies: 21
Views: 734

Re: vcgencmd uses an APOSTROPHE to indicate temperature

I remember ASCII from the 1970s but Linux uses Unicode which has the degree sign in the Basic Latin set - common to all Unicode
by Milliways
Fri May 01, 2020 12:59 am
Forum: General discussion
Topic: vcgencmd uses an APOSTROPHE to indicate temperature
Replies: 21
Views: 734

vcgencmd uses an APOSTROPHE to indicate temperature

It there any reason vcgencmd uses an APOSTROPHE to indicate temperature, rather than the degree sign °

Code: Select all

vcgencmd measure_temp
temp=38.0'C
by Milliways
Sat Apr 25, 2020 5:26 am
Forum: Raspberry Pi OS
Topic: GPIO Readall Code
Replies: 13
Views: 1483

Re: GPIO Readall Code

python GPIOpigpioScript.py File "GPIOpigpioScript.py", line 49 print('|{0:4} | {1[0]:<10} | {1[1]:<4} | {1[2]} |{2:3} '.format(hh, pin_state(hh), h), end='|| ') ^ SyntaxError: invalid syntax Try running the code ACTUALLY listed - which is python3
by Milliways
Sat Apr 25, 2020 5:11 am
Forum: Troubleshooting
Topic: WiringPi on RPI4 Not working
Replies: 3
Views: 212

Re: WiringPi on RPI4 Not working

trying to get wiringpi to work on my board for a PHP project. Nothing I do triggers my LED I have hooked up to pin 7. Any suggestions? I have also tried running it without sudo. pi@raspberrypi:/tmp $ sudo gpio write 7 1 pi@raspberrypi:/tmp $ sudo gpio write 7 0 [/code] WiringPi is deprecated. It do...
by Milliways
Sat Apr 25, 2020 2:47 am
Forum: General discussion
Topic: LEDs and resistors
Replies: 13
Views: 685

Re: LEDs and resistors

There is no need to tell me. You can calculate it yourself
by Milliways
Sat Apr 25, 2020 1:34 am
Forum: General discussion
Topic: LEDs and resistors
Replies: 13
Views: 685

Re: LEDs and resistors

No one can give you a simple answer. You need to know the specs of the LED "5mm" means nothing. Rather than guessing it is simple to calculate. The LED current is (Vcc - Vled)/R White LED have a range of voltages, depending on type - many require higher voltages. See https://en.wikipedia.org/wiki/Li...
by Milliways
Sun Apr 19, 2020 12:40 am
Forum: Beginners
Topic: Two network cards
Replies: 14
Views: 460

Re: Two network cards

If you want a router buy a router.

It will be cheaper and work better.
by Milliways
Thu Apr 16, 2020 1:23 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Best way to get more UART?
Replies: 2
Views: 264

Re: Best way to get more UART?

Get a Pi4 or use software serial.
by Milliways
Sat Apr 11, 2020 1:35 am
Forum: Troubleshooting
Topic: Wiring a Level Shifter
Replies: 8
Views: 273

Re: Wiring a Level Shifter

Frankly using a tri-state buffer is bizarre!

Buy one of the ubiquitous Level Shifter modules which only cost a dollar or so.
by Milliways
Tue Apr 07, 2020 2:03 am
Forum: Beginners
Topic: How to safely connect Relay
Replies: 63
Views: 1732

Re: How to safely connect Relay

The best thing you can do with those poorly designed modules is just to ignore (or remove) the opto-isolators - which add ABSOLUTELY NO isolation and drive the transistor base directly from the Pi. For the benefit of those who will inevitably question the above ANY common connection between the inpu...
by Milliways
Fri Mar 27, 2020 6:29 am
Forum: General discussion
Topic: Foundation Blog
Replies: 8
Views: 475

Foundation Blog

Is there any way to make the Foundation Blog display in list mode like it used to?
by Milliways
Fri Mar 27, 2020 1:22 am
Forum: General discussion
Topic: what happened to the raspberry pi 4 1GB?
Replies: 23
Views: 1177

Re: what happened to the raspberry pi 4 1GB?

I never understood why anyone bought a 1GB model in the first place.

True, I did have to wait 2 weeks for my 2GB Pi4.
by Milliways
Mon Mar 23, 2020 11:42 pm
Forum: Raspberry Pi OS
Topic: update from testing repo?
Replies: 8
Views: 478

Re: update from testing repo?

That's because someone added the unattended upgrade stuff to Raspbian. It's a good idea until someone else publishes a package that breaks everyone's system then it's a s***storm. I have completely disabled that stuff on my systems because I like to retain control. are you saying unattended upgrade...
by Milliways
Sun Mar 15, 2020 11:24 pm
Forum: Beginners
Topic: RTC auto update from NTP
Replies: 15
Views: 756

Re: RTC auto update from NTP

Star297 wrote:
Sun Mar 15, 2020 9:58 pm
Thanks guys ;)

Just one little general question.

A command something like this using the superdoopy command:
sudo timedatectl set-local-rtc 1
Does this get permanently written to flash(SD) or is this only active until re-boot?
Don't do this - Linux normally runs in UTC.
by Milliways
Wed Mar 11, 2020 3:41 am
Forum: General discussion
Topic: Raspberry Pi GPIO and 12v supply
Replies: 10
Views: 608

Re: Raspberry Pi GPIO and 12v supply

Sainsmart 16 channel relay like the hundreds of similar are a crock of S... they don't work with the Pi - they need 5V and each one needs 15-20mA Driver Current and are poor even for the Arduino.

There are hundreds of people who have similar problems.
by Milliways
Wed Mar 11, 2020 3:36 am
Forum: Beginners
Topic: Installing a second os
Replies: 6
Views: 398

Re: Installing a second os

If you do decide to re-install and really want dual boot DON"T use NOOBS use PINN https://github.com/procount/pinn/blob/m ... ME_PINN.md

It is much more flexible. There are extensive PINN posts on this site.
by Milliways
Mon Mar 09, 2020 10:55 am
Forum: Beginners
Topic: Why is NOOBs suggested to be used by Raspberry beginners?
Replies: 51
Views: 3418

Re: Why is NOOBs suggested to be used by Raspberry beginners?

The new imager is INTENDED for beginners, also is clearly useful for everyone. We also provide the SC Card copier (Piclone) for making and restoring backups. But I'm really not sure what you are asking for? A list of installers? What does that mean? And we still have a the ability to download the i...
by Milliways
Mon Mar 09, 2020 9:38 am
Forum: Beginners
Topic: Why is NOOBs suggested to be used by Raspberry beginners?
Replies: 51
Views: 3418

Re: Why is NOOBs suggested to be used by Raspberry beginners?

Could someone check the Downloads page ? NOOBS has disappeared. :? 2020-03-08-181828_1280x1024_scrot.png About time - BUT this is now steering users into a limited option. The Foundation seems unable (or unwilling) to recognise the difference between an OS image and an installer. Ideally we would b...
by Milliways
Sun Mar 08, 2020 2:52 am
Forum: Troubleshooting
Topic: Yellow bolt and undervoltage detection
Replies: 22
Views: 1038

Re: Yellow bolt and undervoltage detection

Power banks are designed to charge batteries NOT provide stable 5V power.

Better cables MAY help, but if the Power bank regulation is poor nothing will help; the only option is a different power source.

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