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by achrn
Sun Oct 24, 2021 7:49 pm
Forum: General discussion
Topic: Hx711 gives random values with RaspberryPi 4
Replies: 10
Views: 440

Re: Hx711 gives random values with RaspberryPi 4

the load cell wire color codes are: red +excitation (power) blk - excitation (power) white and green are the output (differential voltage). this should be VERY small voltages. If you look at the load cell documents, it should specify sensitivity as mV/V Look at the photos. His load cells have three...
by achrn
Sat Oct 23, 2021 5:20 pm
Forum: General discussion
Topic: Hx711 gives random values with RaspberryPi 4
Replies: 10
Views: 440

Re: Hx711 gives random values with RaspberryPi 4

I created a weight scale using a RaspberryPi, Hx711 and 4 load cells. I followed this: https://tutorials-raspberrypi.com/digital-raspberry-pi-scale-weight-sensor-hx711/ tutorial and did everything like shown there. That tutorial describes attaching one single-point four-wire load cell to a HX711 br...
by achrn
Tue Oct 12, 2021 1:47 pm
Forum: General discussion
Topic: ssh connection problem
Replies: 2
Views: 141

Re: ssh connection problem

https://www.raspberrypi.com/documentati ... the-server

If your Pi is headless, note the content of the box that starts "For headless setup,..."
by achrn
Fri Oct 08, 2021 10:12 am
Forum: General discussion
Topic: WARNING: Cancer and Reproductive Harm
Replies: 28
Views: 1474

Re: WARNING: Cancer and Reproductive Harm

W. H. Heydt wrote:
Thu Oct 07, 2021 1:48 pm
Most anything will kill you if you ingest enough of it...including water or oxygen.
They kill you if you have none at all!
by achrn
Wed Sep 08, 2021 3:06 pm
Forum: Networking and servers
Topic: Enable static IP address allocation for clients with wireless access point
Replies: 12
Views: 979

Re: Enable static IP address allocation for clients with wireless access point

Now I tried assigning static IP addresses to the client devices (within the IP address range specified in the DHCP settings) Wrong! Static IP addresses should be chosen from outside the DHCP range. That's not what the dnsmasq man page says: under the section on --dhcp-host= it says "Addresses ...
by achrn
Fri Aug 06, 2021 9:29 am
Forum: General discussion
Topic: Disk space cleanup
Replies: 11
Views: 775

Re: Disk space cleanup

du -s * | sort -rn Puts the largest at the top of the list. I find du -s * | sort -n more useful because the top of the list has normally scrolled off screen - largest at the bottom of the list means the ones that want attention are visible without scrolling back. 'ncdu' is an interactive alternati...
by achrn
Wed Apr 14, 2021 9:19 pm
Forum: General discussion
Topic: Trouble using ssh to login
Replies: 2
Views: 225

Re: Trouble using ssh to login

The network (or maybe just the machine you're running the ssh client on) thinks your Pi is called 'mister', but the pi itself thinks it is called 'birds'.

What is set if you run

Code: Select all

sudo raspi-config
and choose option 2 (network options) then N1 (hostname)?
by achrn
Fri Apr 02, 2021 10:36 am
Forum: General discussion
Topic: Problems with Pi4 2gb bootloader and "locked out" of SSH until WiFi country is set???
Replies: 11
Views: 1106

Re: Problems with Pi4 2gb bootloader and "locked out" of SSH until WiFi country is set???

The problem is that the Pi 4 I am working with will not boot (with headless access over ssh) unless the WiFi country is set first. Yup, that's correct. Not quite. It's not necesary if you don't use WiFi. A headless, screenless, keyboardless boot to ssh connection is perfectly possible without any w...
by achrn
Tue Mar 23, 2021 11:54 am
Forum: General discussion
Topic: What controls time on the Pi?
Replies: 16
Views: 1274

Re: What controls time on the Pi?

When I started this post, I was trying to learn about all the different things that effect the system clock so I could accomplish a particular goal . Since then, I've pretty much accomplished the goal I was after, but I'm still very much curious what keeps resetting the system clock from 2000 to 20...
by achrn
Tue Dec 15, 2020 4:51 pm
Forum: General discussion
Topic: RPi 3 Driving an N-Channel MOSFET
Replies: 15
Views: 941

Re: RPi 3 Driving an N-Channel MOSFET

Consider also that Vgs(th) is the voltage at which it is turning on - it's still a long way from being fully turned on at that voltage. You want to get well above Vgs(th). The max in the datasheet is the highest value that the turn-on starts, effectively. It's not the maximum that Vgs is allowed to ...
by achrn
Tue Nov 17, 2020 9:00 pm
Forum: General discussion
Topic: Help for new PI and clueless parent!
Replies: 15
Views: 791

Re: Help for new PI and clueless parent!

I'd vote for the 'classic' pi rather than the 400 too, largely because I think it is easier to engage with the hardware with that. There is still a kit you can buy with all the main bits (except screen). I'd say buy the 4GB Pi4 version - the 8GB is overkill for nearly everything. I think some of the...
by achrn
Sun Nov 15, 2020 5:12 pm
Forum: General discussion
Topic: Ice tower pi4
Replies: 11
Views: 1786

Re: Ice tower pi4

rudolphhess wrote:
Sun Nov 15, 2020 4:30 pm
I know this is old. But I'm overclocking now so. Which pin is the 5 volt one?
https://pinout.xyz/pinout/5v_power#
by achrn
Sat Nov 14, 2020 2:33 pm
Forum: Troubleshooting
Topic: Pi4 USB boot - different flashing light pattern
Replies: 8
Views: 588

Re: Pi4 USB boot - different flashing light pattern

Something like this: https://www.cpmspectrepi.uk/raspberry_pi/MoinMoinExport/USB3Devices.html#UGREEN_USB-A_to_2.5-inch_SATA_Converter (received yesterday) perhaps? Thanks, I've found (and ordered) what looks like one of them. Also, the listing I ordered from states that it's ASMedia, so will be str...
by achrn
Sat Nov 14, 2020 2:23 pm
Forum: Troubleshooting
Topic: Pi4 USB boot - different flashing light pattern
Replies: 8
Views: 588

Re: Pi4 USB boot - different flashing light pattern

cleverca22 wrote:
Sat Nov 14, 2020 1:42 pm

Code: Select all

dtparam=sd_poll_once
add that to config.txt to make it stop
Excellent, thank you. Increasingly annoying green flicker now stopped.
by achrn
Sat Nov 14, 2020 10:47 am
Forum: Troubleshooting
Topic: Pi4 USB boot - different flashing light pattern
Replies: 8
Views: 588

Re: Pi4 USB boot - different flashing light pattern

Have you tried booting using one of the USB 2 ports on Raspberry Pi 4? Thanks for the suggestion, I've now got it booted (and on the USB3 ports, though the first succesful boot was on a USB2 one). The answer to 'what does a 1.2Hz flickering flash modulated at about 10 times that mean' seems to be, ...
by achrn
Thu Nov 12, 2020 6:08 pm
Forum: Troubleshooting
Topic: Pi4 USB boot - different flashing light pattern
Replies: 8
Views: 588

Re: Pi4 USB boot - different flashing light pattern

https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=290884&p=1758979 Yes, that has the standard 'ASMedia good JMicron bad' advice, but my JMicron, once booted from SDcard, has no UAS errors and achieves slightly in excess of 350MB. I have in any case put the codes in quirks into boot/cm...
by achrn
Thu Nov 12, 2020 5:48 pm
Forum: Troubleshooting
Topic: Pi4 USB boot - different flashing light pattern
Replies: 8
Views: 588

Pi4 USB boot - different flashing light pattern

I'm trying to make a Pi4 USB boot (Sandisk SSD Plus and USB adapter cable). It's headless, and I don't have a micro HDMI adapter or cable to hand. I bought the famed Eluteng blue adaptor (from Amazon, sold by Eluteng) but the one I got (in Eluteng packaging) is not an ASM chip, it's a JMicron idVend...
by achrn
Sat Nov 07, 2020 2:43 pm
Forum: General discussion
Topic: Automatic fan
Replies: 24
Views: 5917

Re: Automatic fan

You need to provide more detail.
What fan?
What command?
by achrn
Fri Nov 06, 2020 8:38 am
Forum: General discussion
Topic: Read data meant for ws2812b led from led controller.
Replies: 2
Views: 255

Re: Read data meant for ws2812b led from led controller.

You're asking if you can use the RPi as a logic Analyser. In principle, yes (I guess), but you wouldnt normally do that because there is cheaper dedicated hardware that does it much better. An ebay search 'analyzer saleae' will turn up 8 channel devices for under 10 pounds (especially if you wait fo...
by achrn
Tue Oct 20, 2020 3:08 pm
Forum: General discussion
Topic: external power supply samsung power bank
Replies: 22
Views: 1309

Re: external power supply samsung power bank

To complete the pendantry... P=vi is only true for Direct Current (DC). For Alternating Current (AC), you need to multiply by 0.7 (actually 1/sqrt(2)) to get the root mean square (RMS) value. "0.7 (actually 1/sqrt(2)) to get the root mean square (RMS) value" would be to convert a peak vol...
by achrn
Tue Oct 20, 2020 7:08 am
Forum: General discussion
Topic: Reliable power-off detection for Pi Zero
Replies: 15
Views: 958

Re: Reliable power-off detection for Pi Zero

GPIO27 works for me on a Pi3 (I don't recall if I've tested it on an actual zero). It goes low on poweroff, though it needs to be set high in the first place (I have that in a script running soon after boot). Other alternatives are listed in the peripherals data sheet https://www.raspberrypi.org/app...
by achrn
Fri Oct 16, 2020 12:48 pm
Forum: General discussion
Topic: Power Multiple Devices including RaspberryPi 4, LED, Speaker etc, using single 12v 3A input
Replies: 7
Views: 452

Re: Power Multiple Devices including RaspberryPi 4, LED, Speaker etc, using single 12v 3A input

https://www.ebay.co.uk/sch/i.html?_nkw=hobbywing+ubec+3a In my testing the Hobbywing 3A UBEC does deliver 3A reliably. I haven't actually run a 4B off one of these very long, but they do deliver 3A for me. If you don't trust it, any other suitable specced non-isolated POL DC-DC convertor will do it....
by achrn
Fri Oct 09, 2020 7:32 am
Forum: General discussion
Topic: What about heat issues on Raspberry Pi 4 Model B ?
Replies: 35
Views: 1894

Re: What about heat issues on Raspberry Pi 4 Model B ?

Heater wrote:
Fri Oct 09, 2020 6:04 am

Something does not add up here.
Bernoulli assumes no energy is added to the system.
A fan adds energy.
by achrn
Mon Oct 05, 2020 3:20 pm
Forum: General discussion
Topic: can i use a 2.1 amp power cord for pi 4
Replies: 37
Views: 1447

Re: can i use a 2.1 amp power cord for pi 4

I wonder why the manufacturer of your RPi board would publish a Specification that says 5V DC via USB-C connector (minimum 3A*) if something of far lower capability would suffice? As a matter of fact something lower than 3A does suffice in many cases. Whether teh particular supply in question will ...
by achrn
Sun Oct 04, 2020 5:38 am
Forum: General discussion
Topic: Power efficiency of official power supply?
Replies: 8
Views: 857

Re: Power efficiency of official power supply?

I am quite concerned at the relatively low load regulation figure of 5%, this means the 5.1V supply might not achieve 4.85V at full load. When I tested an older official PSU it showed a linear characteristic from about 5.2V at 200mA to 4.7V at 3.4A, so at 2A it was about 4.95V. My write-up is at ht...

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