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by RattusRattus
Sun Oct 25, 2020 5:52 pm
Forum: Troubleshooting
Topic: External HDD won't power off when connected to USB3 (Rpi4 B 1.4)
Replies: 1
Views: 42

Re: External HDD won't power off when connected to USB3 (Rpi4 B 1.4)

Having just read the thread that you pointed to it clearly states that the +5V line remains active, so yes I would expect a USB device not to power off... Unfortunately the reduced schematic https://www.raspberrypi.org/documentation/hardware/raspberrypi/schematics/rpi_SCH_4b_4p0_reduced.pdf doesn't ...
by RattusRattus
Sun Oct 25, 2020 3:34 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Switching negative voltages
Replies: 3
Views: 87

Re: Switching negative voltages

Are you sure that you want to switch negative voltages? I think you might be interested in switching a Gate that is negative relative to to the Drain.... a fairly good tutorial series is https://www.electronics-tutorials.ws/category/transistor (TL:DR try this subtopic https://www.electronics-tutoria...
by RattusRattus
Sun Oct 18, 2020 9:48 pm
Forum: General discussion
Topic: Overlay two webcam video feeds for realtime red blue 3D.
Replies: 3
Views: 131

Re: Overlay two webcam video feeds for realtime red blue 3D.

Hi there and welcom to the forum Good question! I can't say that I have an answer for you, only that it sounds possible. If it was me attempting this I would try and split the problem down: #1 convert each stream into black and white in an RGB format, all three colour channels (RG&B) should now be t...
by RattusRattus
Sun Oct 18, 2020 9:03 pm
Forum: General discussion
Topic: How can I see which file is being accessed in SAMBA?
Replies: 2
Views: 121

Re: How can I see which file is being accessed in SAMBA?

try sudo smbstatus -L for more information take a look at the smbstatus manpage :-) This will only show what is open at the time you call smbstatus. HOWEVER, for a lot of programs, the process will be: open a file read entire content if that file into RAM close the file Now, even though the user may...
by RattusRattus
Sun Oct 04, 2020 6:36 pm
Forum: Troubleshooting
Topic: SSH Connection keeps timing out
Replies: 2
Views: 78

Re: SSH Connection keeps timing out

Hi there,

Sounds like the IP address that you used to have for your RPi has changed.

I am making an assumption that you get IP address assignation using DHCP from your wifi/router? if so have a look on your router to see what new address your RPi has been given...

/Andy
by RattusRattus
Sat Sep 19, 2020 10:12 pm
Forum: Compute Module
Topic: thinner/flusher connector for SODIMM and CM3+
Replies: 18
Views: 683

Re: thinner/flusher connector for SODIMM and CM3+

Don't forget SODIMM connectors have mechanical retention on the SIDE of the module, so you would need to look at that as well


/Andy
by RattusRattus
Sat Sep 19, 2020 5:56 pm
Forum: Troubleshooting
Topic: ACR122U
Replies: 4
Views: 183

Re: ACR122U

looks like your nfc reader isn't being recognised.

what does

Code: Select all

lsusb
say?

/Andy
by RattusRattus
Fri Sep 18, 2020 5:53 pm
Forum: Beginners
Topic: Serial mystery....
Replies: 6
Views: 271

Re: Serial mystery....

Hi Martin It is entirely possible that yes they have just used USB socket for power only. I guess you can take it apart and buzz out where the lines go. if it really is a USB port D+ and D- lines should go through an ESD filter (may be missing for cheap stuff) and then onto the microcontroller. you ...
by RattusRattus
Fri Sep 18, 2020 3:54 pm
Forum: Beginners
Topic: How increase performance to 12mbps (ProfiBUS)?
Replies: 1
Views: 119

Re: How increase performance to 12mbps (ProfiBUS)?

Hi If I have understood your post correctly you are reading information from a serial port, and are having problems processing an incoming message before the start of the next message. The normal way to handle this is to place all incoming data into a buffer; under interrupts from the serial port ha...
by RattusRattus
Fri Sep 18, 2020 3:32 pm
Forum: Beginners
Topic: Serial mystery....
Replies: 6
Views: 271

Re: Serial mystery....

You need to provide more than "I have brought a thing and I don't know how to use it" (1) What is is? Make Model Supplier weblink etc (2) What is it supposed to do? It is a battery monitor sure, but describe it a bit better, what information is SUPPOSED to be presented on these magic two pins /Andy
by RattusRattus
Mon Sep 14, 2020 6:58 am
Forum: Troubleshooting
Topic: Problem powering up H-Bridge
Replies: 6
Views: 153

Re: Problem powering up H-Bridge

Many thanks for the drawing - they ALWAYS help :-) (1) Just to be 100% clear, your cables between the H-Bridges and Arduinos - they do contain a ground connection? (2) can you check the 'step-down' power supply: (2a) What is its output current rating? (2b) Is this a floating isolated power supply (i...
by RattusRattus
Sun Sep 13, 2020 7:18 pm
Forum: Troubleshooting
Topic: Problem powering up H-Bridge
Replies: 6
Views: 153

Re: Problem powering up H-Bridge

Hi there,

Please draw a diagram of what is connected and where

Please also show the power and ground connections

Thanks

/Andy
by RattusRattus
Sat Sep 12, 2020 4:40 pm
Forum: Beginners
Topic: create asd image of my raspbian os
Replies: 6
Views: 261

Re: create asd image of my raspbian os

Hi there In your pc you say the whole of the uSD card showes up as SDD So simply change if=/dev/sd b to if=dev/sd d you may want to add some additional options to your invocation of 'dd': bs=4M (set read and write block size to 4 Megabytes - this speeds up the whole process) status=progress (shows p...
by RattusRattus
Sat Sep 12, 2020 4:29 pm
Forum: Advanced users
Topic: How do I boot other OS from USB.
Replies: 1
Views: 162

Re: How do I boot other OS from USB.

Put an RPi build of EDK_2 on a uSD card this will give a functioning EUFI environment [0] You can then boot any of the normal Linux distros built for ARM32/64 with their installation image on a USB device. For example you can use a standard Debian installer on your USB stick (either ARMHF or ARM64) ...
by RattusRattus
Sat Sep 12, 2020 9:48 am
Forum: General discussion
Topic: Snychronizing GPIO Pins of mutliple PIs
Replies: 4
Views: 186

Re: Snychronizing GPIO Pins of mutliple PIs

It is all down to the interval of time you are prepared to accept as 'being in sync'.

For many applications within a second is more than good enough, a few milliseconds (<100ms) with a sub 10ms jitter may be acceptable for many more applications, for others it may not.

/Andy
by RattusRattus
Sat Sep 12, 2020 9:39 am
Forum: Advanced users
Topic: Ways to connect Master Pi and Slave Pi Connections
Replies: 26
Views: 948

Re: Ways to connect Master Pi and Slave Pi Connections

on thagrol » Fri Sep 11, 2020 11:27 pm Is there a strong reason for not connecting all the sensors directly to the master Pi? Yes sensor location Your sensors may be located too far apart to reasonably drive them from a single device Timing Unless you are running your RPi bare metal (i.e. without a ...
by RattusRattus
Fri Sep 11, 2020 10:51 pm
Forum: Advanced users
Topic: Ways to connect Master Pi and Slave Pi Connections
Replies: 26
Views: 948

Re: Ways to connect Master Pi and Slave Pi Connections

jriffel if you have many sensors are they all local to one machine, i.e. can one machine drive all of the sensors separately? if the sensors will be too far apart to make driving the sensors from a singe machine a viable proposition then you will need multiple machines to drive your sensors and then...
by RattusRattus
Fri Sep 11, 2020 10:34 pm
Forum: Advanced users
Topic: Ways to connect Master Pi and Slave Pi Connections
Replies: 26
Views: 948

Re: Ways to connect Master Pi and Slave Pi Connections

Before you try and make one big application, it is probably worth finding out about the various communication options available to you, and experimenting with some of the interfaces to find the one best suited for your needs. Take a look at Asynchronous Serial, I2C and SPI. All three methods of Seri...
by RattusRattus
Fri Sep 11, 2020 6:14 pm
Forum: Python
Topic: Multiple DS18B20's, best way to code (Python) for multiple sensors? [Solved]
Replies: 14
Views: 511

Re: Multiple DS18B20's, best way to code (Python) for multiple sensors? [Solved]

hi again Just comming back about part numbering DS18B20, DS18B20+, DS18B20+Par, DS18B20+Par+T&R and DS18B20-Par+T&R DS18B20 this is the original Dallas Semiconductor part (not being RoSH compliant this is unsuitable for most commercial products) DS18B20+ same part but RoHS compliant (i.e. lead free ...
by RattusRattus
Wed Sep 09, 2020 4:01 pm
Forum: Python
Topic: Multiple DS18B20's, best way to code (Python) for multiple sensors? [Solved]
Replies: 14
Views: 511

Re: Multiple DS18B20's, best way to code (Python) for multiple sensors?

Off topic but this may be useful Be aware that unless you buy you DS18B20's from mainline distribution the chances are they are fake (0)(1) Certainly EVERY ebay, & amazon seller I have brought from (8 different vendors) has been selling counterfeit parts - Your experience may vary. My experience wa...
by RattusRattus
Wed Sep 09, 2020 8:55 am
Forum: Beginners
Topic: Interface problem between Arduino and RPI, through pin 7 arduino. and pin 7 RPI
Replies: 10
Views: 297

Re: Interface problem between Arduino and RPI, through pin 7 arduino. and pin 7 RPI

You initially said that when you read the input from you Arduino it was all over the place. Connecting an LED will not tell you if it is a steady state or oscillating if the line is switching often enough. Please consider the initial steps I suggested and perhaps share a drawing of what is connected...
by RattusRattus
Mon Sep 07, 2020 4:05 pm
Forum: Beginners
Topic: Interface problem between Arduino and RPI, through pin 7 arduino. and pin 7 RPI
Replies: 10
Views: 297

Re: Interface problem between Arduino and RPI, through pin 7 arduino. and pin 7 RPI

Hi there First lets find out if your problem is on the Arduino or RPi... i.e. is the problem writing data out or reading it in? Instead of connecting your Arduino to pin 7 of your Pi attach Pin 7 of your Pi to 0V. (1) When you try and read the pin does it always show 0? (2) now connect pin 7 of your...
by RattusRattus
Mon Sep 07, 2020 3:48 pm
Forum: Beginners
Topic: How to add and control Fan in RPi4 without other power source
Replies: 11
Views: 461

Re: How to add and control Fan in RPi4 without other power source

Take a look at the fan shim

even if you don't use the shim hardware there is plenty of cribs available in the supporting code...

https://learn.pimoroni.com/tutorial/san ... h-fan-shim
https://github.com/pimoroni/fanshim-python

/Andy
by RattusRattus
Mon Sep 07, 2020 1:48 pm
Forum: Troubleshooting
Topic: issues with GPIO/button push
Replies: 1
Views: 57

Re: issues with GPIO/button push

hi there Switches are just bits of metal that you join together or pull apart when you close or open them. During the transition from open to closed the switch contacts will often bounce a few times before coming to rest in their new closed state. This may take a few microseconds (millionths of a se...

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