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by IanS
Fri Apr 05, 2019 9:30 am
Forum: Networking and servers
Topic: Data diode using Pi
Replies: 3
Views: 1095

Re: Data diode using Pi

That depends on what you mean by Ethernet. Ethernet is really just a way of moving packets across the network, so layers 1 and 2 (physical and datalink) of the standard OSI network model. Above that you get various other protocols. e.g. IP is layer 3, TCP and UDP are layer 4, etc. Fibre connections ...
by IanS
Mon Apr 01, 2019 9:27 am
Forum: Networking and servers
Topic: Communicating between Pi and Arduino
Replies: 2
Views: 172

Re: Communicating between Pi and Arduino

MQTT supports a number of ways to connect and then a number of levels of assurance that the message gets through. You can use encrypted connections via TLS, which of course adds an overhead, but if you do not need that security then you can skip that. There are then three levels of assurance - best ...
by IanS
Wed Mar 27, 2019 4:44 pm
Forum: Gentoo
Topic: [SOLVED] Behringer UCA202 or HiFiBerry DAC+?
Replies: 8
Views: 454

Re: Behringer UCA202 or HiFiBerry DAC+?

I've used UCA202/222s (the only difference is the colour and the bundled WIndows software) in Pi music projects with no crackles. I have a bit of hiss, but given that I am running them in a very noisy (electronically) environment, I am pretty certain that is an outside influence. I have used them el...
by IanS
Tue Mar 26, 2019 9:46 am
Forum: Automation, sensing and robotics
Topic: Raspberry Pi, Arduino and I2C
Replies: 5
Views: 184

Re: Raspberry Pi, Arduino and I2C

If you connect the three devices that way you could end up with fried raspberry. The Pi GPIO pins can only accept 3.3V inputs, but the arduino uses 5V. You are also powering the sensor with 5V, so that is likely to have 5V output on the logic lines too. The I2C protocol dictates that the lines are p...
by IanS
Wed Mar 20, 2019 8:57 am
Forum: Automation, sensing and robotics
Topic: Best way to get reading from hundreds of LDRs into RPi?
Replies: 15
Views: 948

Re: Best way to get reading from hundreds of LDRs into RPi?

Connecting the LDRs in a matrix is a good way of reading lots of values with a limited number of A2D converters, and the same layout is used to read a switch matrix. However, there is a problem with switch matrices when multiple switches are triggered, and the same problem will apply here. Look up s...
by IanS
Wed Mar 13, 2019 9:43 am
Forum: Other projects
Topic: Reading audio on Raspberry pi Zero W (stretch)
Replies: 2
Views: 167

Re: Reading audio on Raspberry pi Zero W (stretch)

You say that the audio is streamed from the phone. Have you got it so that the audio can be heard, output through the Pi? If so, then you need a way to capture the audio output. You might be running the ALSA sound toolkit, which is the default for Raspbian but I do not know about other distributions...
by IanS
Tue Mar 12, 2019 5:14 pm
Forum: Automation, sensing and robotics
Topic: CNC controlled nail gun
Replies: 16
Views: 786

Re: CNC controlled nail gun

A conventional motor's speed can be controlled by changing the supplied voltage, within the motor limits, and can handle sudden jumps in the voltage without a problem. A stepper motor speed is controlled by the step rate, and cannot handle sudden jumps. If you have a stationary motor and you try and...
by IanS
Wed Mar 06, 2019 10:39 am
Forum: Networking and servers
Topic: install a firewall on raspberrypi
Replies: 2
Views: 224

Re: install a firewall on raspberrypi

If the Pi is acting as a gateway router (all devices send traffic to the Pi, which then sends it on) then you can control pretty much anything going through it. Time-based control may need the functionality provided by a captive portal, but just about everything else is covered by the 'Linux Advance...
by IanS
Wed Mar 06, 2019 10:21 am
Forum: Networking and servers
Topic: How to build undetectable ethernet sniffer?
Replies: 8
Views: 735

Re: How to build undetectable ethernet sniffer?

Fully agree Jamesh. Anybody interfering (traffic interception counts) with any IT system should have the written/email permission of the person with authority for that network. However, when you do have permission to run sniffers, honeypots, and even targeted hacks in a corporate environment it is a...
by IanS
Tue Mar 05, 2019 12:44 pm
Forum: Networking and servers
Topic: How to build undetectable ethernet sniffer?
Replies: 8
Views: 735

Re: How to build undetectable ethernet sniffer?

As already mentioned, switches learn which ports lead to which devices, and only send packets out of the correct port. Some traffic, like broadcasts, obviously need to go out of all ports. This limits what you can capture. There are at least three ways around this. Use a SPAN port as already mention...
by IanS
Tue Mar 05, 2019 12:09 pm
Forum: Advanced users
Topic: Ping sweep of my network
Replies: 15
Views: 608

Re: Ping sweep of my network

Zabbix is a lot easier to get up and configured than the base Nagios build, but there is now a Raspberry targeted version of Nagios (https://nemslinux.com/) with an improved interface which might make things easier.
by IanS
Tue Feb 26, 2019 10:49 am
Forum: Automation, sensing and robotics
Topic: Raspberry pi3 with arduino like slave to read 5 analogic signals
Replies: 6
Views: 354

Re: Raspberry pi3 with arduino like slave to read 5 analogic signals

Serial.print("1:"); Serial.print(analogRead(A1)); Serial.print ( ",2:"); Serial.print(analogRead(A2)); Serial.print ( ",3:"); Serial.print(analogRead(A3)); Serial.print ( ",4:"); Serial.print(analogRead(A4)); Serial.print ( ","); Then it does not matter whether you read a subset or superset of the o...
by IanS
Tue Feb 26, 2019 10:44 am
Forum: Automation, sensing and robotics
Topic: Sensing the level/volume of a tank full with woodchips
Replies: 13
Views: 697

Re: Sensing the level/volume of a tank full with woodchips

A cut could seriously weaken the tank. How about a high-contrast not-wood-or-tank-colour strip stuck to one inside wall and a camera mounted on the opposite lip. Then see how much of the strip you can see.
Just don't put the camera where it might get damaged getting the chips in or out.
by IanS
Mon Feb 04, 2019 1:14 pm
Forum: Other projects
Topic: I need to build a "force-you-out-of-bed" alarm.
Replies: 1
Views: 186

Re: I need to build a "force-you-out-of-bed" alarm.

Since you have Python experience, use it. Start by understanding how to use one sensor at a time. Look up tutorials on one of the python libraries that talk to the GPIO pins for you, such as GPIOzero. Understand the difference between configuring inputs as pull-up or pull-down. If the input is pulle...
by IanS
Sun Feb 03, 2019 9:19 pm
Forum: Advanced users
Topic: Determining if SSH outbound connection has been made
Replies: 4
Views: 250

Re: Determining if SSH outbound connection has been made

You could look at the output of 'netstat -ant'. While a connection is active you will have a line with [ip]:22 in the local column if the connection is to that machine, or in the foreign column if it is from that machine. If you miss out the 'n' from the options then it will be reported as [ip]:ssh....
by IanS
Fri Jan 25, 2019 10:17 am
Forum: Networking and servers
Topic: Raspberry Pi One Master and Multiple Slaves with ethernet
Replies: 2
Views: 280

Re: Raspberry Pi One Master and Multiple Slaves with ethernet

You can do it at a socket level, but you have to develop your own error handling. UDP is easier to implement to start with, but not as reliable as TCP. Alternatively look at using a message protocol and broker such as mqtt and mosquitto. Each motor controller would subscribe to its own channel, and ...
by IanS
Fri Jan 25, 2019 10:03 am
Forum: Graphics, sound and multimedia
Topic: Replace volume control of USB speaker with a potentiometer
Replies: 17
Views: 856

Re: Replace volume control of USB speaker with a potentiometer

I am guessing that you made a typo, and that 1.75 should have been 17.5. The halfway reading should be between the two end readings. As already mentioned, measuring the values with the pot in place may not be completely accurate, as there may be alternate connectivity paths. Measure the resistance b...
by IanS
Wed Jan 02, 2019 3:09 pm
Forum: Networking and servers
Topic: Using raspberry pi as a firewall
Replies: 1
Views: 777

Re: Using raspberry pi as a firewall

From a software side you need to enable what is known as IP forwarding. There are plenty of on-line guides covering this, although most of them are about disabling rather enabling it, as it is only needed when the box is acting as a router and can be a security problem in other cases. You then use i...
by IanS
Mon Dec 03, 2018 9:38 am
Forum: Advanced users
Topic: Cloning SD Cards Using Windows
Replies: 3
Views: 757

Re: Cloning SD Cards Using Windows

With any imaging tool that copies the entire media, whether allocated to a partition or not, be aware that not all SD cards are the same capacity for a given label. An '8GB' card might vary slightly from one manufacturer to another. Copying card1 -> image -> card2 will work if card2 is the same size...
by IanS
Wed Nov 07, 2018 12:42 pm
Forum: Automation, sensing and robotics
Topic: pi 3B+ driven camera gimbal, considerations
Replies: 4
Views: 483

Re: pi 3B+ driven camera gimbal, considerations

Brushless motors are normally used for high-power, high-speed systems, such as spinning the blades on a quad-copter. Are you sure this is what you want? Camera position control is normally done by using motors which can go to a defined position accurately. For a small rig this would be done by servo...
by IanS
Tue Oct 30, 2018 2:27 pm
Forum: Networking and servers
Topic: owncloud client/server incompatibility after upgrade
Replies: 8
Views: 828

Re: owncloud client/server incompatibility after upgrade

There is a QWebView module as part of Qt5. That may be the one you are looking for.
by IanS
Mon Oct 29, 2018 11:11 am
Forum: Graphics, sound and multimedia
Topic: Raspberry Pi (any model) as a midi encoder and interface
Replies: 6
Views: 1516

Re: Raspberry Pi (any model) as a midi encoder and interface

Hi Brian, I am working on a very similar project, although the pedalboard is still a pile of loose ash pieces in my workshop at the moment apart from a 2 note prototype - building a 32 note concave and radiating pedalboard from scratch takes a while. The manuals and stops are up and running though. ...
by IanS
Fri Oct 19, 2018 11:16 am
Forum: Graphics, sound and multimedia
Topic: Building a midi controlled LED Bar
Replies: 1
Views: 895

Re: Building a midi controlled LED Bar

It is certainly possible, assuming that your keyboard has a midi output already available. You need a midi input on the Pi, and although you can build one which links into the serial port GPIOs (midi is a serial interface afterall), the particular speed that midi runs at is awkward to match. Buying ...
by IanS
Thu Oct 11, 2018 4:16 pm
Forum: Networking and servers
Topic: Gigabit ethernet on Raspberry 3
Replies: 15
Views: 59921

Re: Gigabit ethernet on Raspberry 3

How old was your networking course? I can conceive that a network hub which supports multiple speeds might knock everything down to the lowest speed connection, but switches and routers generally handle mixed connections with no problem. Hubs are very rare these days, as they handle traffic very ine...
by IanS
Thu Oct 11, 2018 4:02 pm
Forum: Other projects
Topic: making a digital piano : is the rpi fast enough ?
Replies: 13
Views: 2166

Re: making a digital piano : is the rpi fast enough ?

Yes an RPi is fast enough. I am part way through building an organ, which you can consider as being a stack of pianos, one of which is foot operated. There is then the complication of multiple stops (so one note press triggers multiple sounds), and couplers (where a note on one keyboard triggers the...

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