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by IanS
Wed Apr 01, 2020 9:25 am
Forum: Automation, sensing and robotics
Topic: Raspberry Pi, Arduino Nano, MPU6050
Replies: 1
Views: 56

Re: Raspberry Pi, Arduino Nano, MPU6050

The Pi has two UARTs which can be used for serial communications. See https://www.raspberrypi.org/documentation/configuration/uart.md . The Arduino can also do serial communications through USB and also via the RX and TX pins. However, the Pi uses 3.3V logic and the Arduino varies by board type. The...
by IanS
Thu Mar 26, 2020 11:57 am
Forum: Automation, sensing and robotics
Topic: Fast Raspberry Pi Car Bot Running Companion
Replies: 5
Views: 306

Re: Fast Raspberry Pi Car Bot Running Companion

If a slower acceleration is OK (e.g. the bot starts behind the runner and gets up to speed, then the runner stays with it), then a larger wheeled vehicle could use slower and less powerful motors. Also gives you room to carry a bigger battery, so it can be used for longer. Once you get the bot movin...
by IanS
Thu Mar 26, 2020 11:09 am
Forum: Advanced users
Topic: RPI VPN, PiHole, CloudFlare DoH and now Snort?
Replies: 7
Views: 1236

Re: RPI VPN, PiHole, CloudFlare DoH and now Snort?

For anybody else finding this old thread, there is an lighter weight alternative to Snort called Bro. See https://www.tripwire.com/state-of-secur ... pberry-pi/ for an example of how it might be set up with other security tools.
by IanS
Sat Mar 21, 2020 9:38 pm
Forum: Automation, sensing and robotics
Topic: Fast Raspberry Pi Car Bot Running Companion
Replies: 5
Views: 306

Re: Fast Raspberry Pi Car Bot Running Companion

15mph might not sound very fast for a vehicle, but let's examine it in more detail. 15mph = 15 * 1760 * 36 / 60 = 15,840 inches per minute. Fairly big wheels for a small robot wheel might be 4 inches in diameter, so 4 * pi = 12.6 inches circumference. This gives you a needed motor speed of 15840/12....
by IanS
Sat Mar 21, 2020 8:27 pm
Forum: Advanced users
Topic: Elasticsearch (ELK)
Replies: 2
Views: 184

Re: Elasticsearch (ELK)

I got it running on a 3B+, albeit in a very limited fashion. Moving it to a 4GB Pi4 made a big difference to performance. You really need the extra memory. Google for installation methods - that's how I found working instructions. You cannot run the latest version of the stack. I believe it went to ...
by IanS
Mon Mar 09, 2020 3:53 pm
Forum: Networking and servers
Topic: Problems adding a USB 3.0 SSD to PI4
Replies: 31
Views: 1522

Re: Problems adding a USB 3.0 SSD to PI4

I have a Pi4 with USB3 SSD that works fine with no tweaks required, other than repointing the root device in the SD card /boot/cmdline.txt to the USB drive. The USB adapter is a StarTech USB3S2SAT3CB ( https://www.amazon.co.uk/gp/product/B00HJZJI84 ), and the SSD is a Crucial BX500 CT120BX500SSD1(Z...
by IanS
Tue Mar 03, 2020 2:02 pm
Forum: Networking and servers
Topic: Problems adding a USB 3.0 SSD to PI4
Replies: 31
Views: 1522

Re: Problems adding a USB 3.0 SSD to PI4

I have a Pi4 with USB3 SSD that works fine with no tweaks required, other than repointing the root device in the SD card /boot/cmdline.txt to the USB drive. The USB adapter is a StarTech USB3S2SAT3CB ( https://www.amazon.co.uk/gp/product/B00HJZJI84 ), and the SSD is a Crucial BX500 CT120BX500SSD1(Z)...
by IanS
Mon Feb 24, 2020 1:51 pm
Forum: Other projects
Topic: PI to control device at random voltage for random duration
Replies: 1
Views: 165

Re: PI to control device at random voltage for random duration

Look into how electronic speed controllers work for motors. They are basically a MOSFET switched on and off very quickly (typically around 2000Hz) using pulse width modulation. There may be a bit of smoothing (e.g. a capacitor) on the output and a flyback diode to protect against reverse voltage spi...
by IanS
Fri Feb 21, 2020 9:09 am
Forum: Troubleshooting
Topic: Pi4 kernel modules vanish after apt upgrade
Replies: 2
Views: 165

Re: Pi4 kernel modules vanish after apt upgrade

I used apt upgrade. Having now tried full-upgrade, that worked successfully. The apt history log shows the same 41 packages, at the same versions as the list above. $ cat /var/log/apt/history.log Start-Date: 2020-02-21 08:42:48 Commandline: apt full-upgrade Requested-By: pi (1000) Upgrade: libpython...
by IanS
Thu Feb 20, 2020 10:41 am
Forum: Troubleshooting
Topic: Pi4 kernel modules vanish after apt upgrade
Replies: 2
Views: 165

Pi4 kernel modules vanish after apt upgrade

After running an apt update+upgrade cycle which brought in a set of 41 upgrades with very tangled interdependencies, my wireless interface vanished. Not just needed reconfiguring, but totally vanished. The options in raspi-config for setting the wireless country, ssid+password, etc report that there...
by IanS
Tue Feb 18, 2020 11:19 am
Forum: Automation, sensing and robotics
Topic: What are Realistic CNC X Y Z maximums for a PI CNC
Replies: 2
Views: 245

Re: What are Realistic CNC X Y Z maximums for a PI CNC

The size of a CNC machine is purely a mechanical problem. On the Pi side the position is just a number, and despite being a little computer, it can still cope with big numbers. Larger CNC machines still need to be rigid, which leads to heavier gantry/platform weight, which leads to more powerful mot...
by IanS
Wed Feb 05, 2020 11:20 am
Forum: Advanced users
Topic: 250 ft cable: Use VNC or Monitor?
Replies: 7
Views: 945

Re: 250 ft cable: Use VNC or Monitor?

250 feet of cabling is a serious drag on a robot. You should be considering the physical properties of the wire too. How heavy is it? How easily does it go around corners? (Assuming it is not just a straight pipe you are going down.) How can you avoid getting tangled when you manoeuvre back through ...
by IanS
Wed Sep 25, 2019 4:13 pm
Forum: Automation, sensing and robotics
Topic: Automated Projector Screen With Raspberry Pi
Replies: 2
Views: 434

Re: Automated Projector Screen With Raspberry Pi

One possibility is to have the power to the raspberry turned on at the same time as the projector. It would then lower the screen on boot. Your problem then moves to the end of the film, when you need to signal it to retract the screen and shutdown cleanly. Controlling a relay is trivial - you will ...
by IanS
Mon Sep 23, 2019 8:26 am
Forum: Automation, sensing and robotics
Topic: 2 Stepper Motors; Independent control
Replies: 8
Views: 1736

Re: 2 Stepper Motors; Independent control

I would suggest having end-stop switches on the back-and-forth motion. Then, move to and fro until the switches trigger instead of going a fixed distance. This way you can cope with skipped steps and it does not matter if the power gets interrupts part way along leaving the device to restart in an u...
by IanS
Mon Sep 09, 2019 7:43 am
Forum: Automation, sensing and robotics
Topic: Terrarium mister wiring diagram
Replies: 2
Views: 301

Re: Terrarium mister wiring diagram

The DHT11 or 22 sensors will run from 3V3. This way you will not fry your GPIO input port with the signal return. Most tutorials (e.g. https://www.raspberrypi-spy.co.uk/2017/09/dht11-temperature-and-humidity-sensor-raspberry-pi/ ) include a 10K pull up resistor between data and V+, although you migh...
by IanS
Mon Aug 05, 2019 8:47 am
Forum: General discussion
Topic: Pm SDS011
Replies: 1
Views: 489

Re: Pm SDS011

I have just finished building something very similar. I use a DHT22 sensor for measuring temperature and humidity, and an SDS011 for PM2.5 and PM10 levels. A MariaDB table holds the historical values which can be displayed using a Grafana web front-end and a 2x16 LCD display with an I2C backpack sho...
by IanS
Fri Aug 02, 2019 5:23 pm
Forum: Other projects
Topic: Raspberry PIpe Organ
Replies: 11
Views: 3392

Re: Raspberry PIpe Organ

There is no problem ... if the midi controller is implemented properly. Some low quality organ midi systems will not start a new sound if an additional stop is activated while a chord is held, or stop that sound if the stop is deactivated while the chord continues. They only generate note on/off whe...
by IanS
Fri Jul 12, 2019 2:06 pm
Forum: Other projects
Topic: Raspberry PIpe Organ
Replies: 11
Views: 3392

Re: Raspberry PIpe Organ

MIDI is good for most instruments, but can struggle with 'real' organs. The problem is that it does not send 'keyboard note down', 'keyboard note up' messages, but sends 'note on', 'note off'. Since having multiple stops out means that each press of a keyboard note generates multiple sounds, the MID...
by IanS
Tue Jul 09, 2019 2:49 pm
Forum: Raspbian
Topic: Authentication required to mount USB
Replies: 1
Views: 415

Re: Authentication required to mount USB

Do you have a line in /etc/fstab describing where to mount it?
It would probably look something like:

Code: Select all

/dev/sda1	/mnt/usb	vfat	defaults	0	0
This translates as mount the /dev/sda1 device with a vfat filesystem at /mnt/usb. See 'man fstab' for the other parameters.
by IanS
Thu Jul 04, 2019 11:19 am
Forum: Other projects
Topic: Raspberry PIpe Organ
Replies: 11
Views: 3392

Re: Raspberry PIpe Organ

I have a similar project you might be able to borrow bits from. I am building an organ console (two manuals and stops up and running so far, pedalboard still under construction) where the note press/release and stop statuses are monitored by a Pi, and then the status changes communicated to a sound ...
by IanS
Tue Jun 18, 2019 10:18 am
Forum: Graphics, sound and multimedia
Topic: Do you use a USB audio interface with Raspberry Pi?
Replies: 3
Views: 1392

Re: Do you use a USB audio interface with Raspberry Pi?

I use Behringer UCA202/222s, because I need something with RCA connectors rather than jack sockets but still cheap. The sound quality is good, but I cannot get them to work in stereo mode for some reason. ALSA sees them as a single channel device.
by IanS
Fri Jun 07, 2019 8:27 am
Forum: Automation, sensing and robotics
Topic: Issue with ultrasonic sensor
Replies: 5
Views: 541

Re: Issue with ultrasonic sensor

Which version of GPIOZero are you using? Before v1.5 there were problems with the DistanceSensor code on Zeros, although other models seemed to work better.
by IanS
Wed May 15, 2019 4:06 pm
Forum: Other projects
Topic: stepper motors rattling
Replies: 4
Views: 729

Re: stepper motors rattling

Looking at your code, you are sending high and low signals for equal times. Many stepper motor controls only need a short pulse (1-2 microseconds) at the required rate. Whether this should be high pulses from a low background or low pulses from a high background may depend on the stepper controller....
by IanS
Tue May 14, 2019 8:40 am
Forum: Other projects
Topic: stepper motors rattling
Replies: 4
Views: 729

Re: stepper motors rattling

Can you drive the motor at a much lower speed? Stepper motors sometimes have a resonant frequency range that is harder to drive, although half- or micro-stepping can help.
by IanS
Wed May 08, 2019 9:41 am
Forum: Networking and servers
Topic: Pi UPS and Connectivity Monitor
Replies: 2
Views: 877

Re: Pi UPS and Connectivity Monitor

For the UPS side, it might be easier to find a small UPS that is supported by NUT ( https://networkupstools.org/ ). There are small UPS devices specifically targeted at the Pi, but I do not know if they support anything like battery level querying. For the modem reset you could use a GPIO controlled...

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