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by Pekka
Tue May 19, 2020 4:41 am
Forum: Troubleshooting
Topic: RPI keyboard, where is the insert key?
Replies: 4
Views: 266

Re: RPI keyboard, where is the insert key?

Who needs an 'insert' key?
I do. For selecting files in mc. Having to press Fn for that on the RPi keyboard is indeed somewhat annoying.
by Pekka
Wed Apr 29, 2020 10:10 am
Forum: Beginners
Topic: DCF77 time signal emulator by Raspberry Pi Zero WH
Replies: 12
Views: 558

Re: DCF77 time signal emulator by Raspberry Pi Zero WH

-1 keeps it running until you kill it. The image of my Zero W with the antenna looks like this. It has a heatshrink over it, but underneath is a coil with the right number of turns and a proper capacitor.
by Pekka
Tue Apr 28, 2020 12:33 pm
Forum: Beginners
Topic: DCF77 time signal emulator by Raspberry Pi Zero WH
Replies: 12
Views: 558

Re: DCF77 time signal emulator by Raspberry Pi Zero WH

My antenna coil is made of stranded wire 0,5mm only 10 turns diam 7cm and no ferrite core. My experience shows that it's realy worth using a properly tuned ferrite-core antena. I have a Casio Lineage watch that won't even start receiving signal without one. With one, it will happily synchronise som...
by Pekka
Tue Apr 28, 2020 10:36 am
Forum: Beginners
Topic: DCF77 time signal emulator by Raspberry Pi Zero WH
Replies: 12
Views: 558

Re: DCF77 time signal emulator by Raspberry Pi Zero WH

dcfake77 will wait until the next full minute until it starts sending pulses to GPIO. Like this: pekka@dcftx:~$ sudo dcfake77 -1 [sudo] password for pekka: Waiting for next minute start 2020-04-28@12:30:44 2020-04-28@12:30:45 2020-04-28@12:30:46 2020-04-28@12:30:47 2020-04-28@12:30:48 2020-04-28@12:...
by Pekka
Thu Apr 23, 2020 4:22 am
Forum: Beginners
Topic: DCF77 time signal emulator by Raspberry Pi Zero WH
Replies: 12
Views: 558

Re: DCF77 time signal emulator by Raspberry Pi Zero WH

You download the source from github, compile it, make it executable and run it at the appropriate time. Like this: wget https://raw.githubusercontent.com/luigicalligaris/dcfake77/master/dcfake77-raspberry/dcfake77-raspberry.c gcc -odcfake77 dcfake77-raspberry.c chmod +x dcfake77 sudo ./dcfake77 20 T...
by Pekka
Wed Apr 22, 2020 9:22 am
Forum: Beginners
Topic: DCF77 time signal emulator by Raspberry Pi Zero WH
Replies: 12
Views: 558

Re: DCF77 time signal emulator by Raspberry Pi Zero WH

I use a Zero W with a tuned ferrite antenna (obtained from an old DCF77 alarm clock), connected with a 330 ohm resistor in series to the GPIO pin 4. I use the software from https://github.com/luigicalligaris/dcfake77 . I let it run as a cron job for 20 min at 0200 and 0300 every night (as this is wh...
by Pekka
Thu Feb 20, 2020 5:24 am
Forum: Troubleshooting
Topic: Raspberry Pi 4 - very slow 2D graphic and DOSBox
Replies: 6
Views: 929

Re: Raspberry Pi 4 - very slow 2D graphic and DOSBox

To answer my own question: it seems that xcompmgr is the culprit. Disabling it makes Allegro games run at full speed again. Still, it would make sense to research as to why this is so.
by Pekka
Thu Feb 13, 2020 7:12 am
Forum: Troubleshooting
Topic: Raspberry Pi 4 - very slow 2D graphic and DOSBox
Replies: 6
Views: 929

Re: Raspberry Pi 4 - very slow 2D graphic and DOSBox

It's a me-too with this. I have some games using Allegro 4 that work perfectly OK even on RPi 1 but are unusably slow on my new RPi 4 using a clean install of the latest (2020-02-05) Raspbian Buster with Desktop. I tried to re-compile them on the RPi 4 but to no avail. It seems that this has somethi...
by Pekka
Sat Jan 25, 2020 1:50 pm
Forum: Troubleshooting
Topic: Camera not detected despite being plugged in
Replies: 19
Views: 2229

Re: Camera not detected despite being plugged in

Out of interest, how long ago was that? I’m just wondering if you might’ve had the same version of whatever software I updated just before the issue started on my systems... My four Zero Ws are all running the same version of Raspbian Stretch Lite from early 2018 with kernel 4.19.93 and MJPG Stream...
by Pekka
Thu Jan 23, 2020 6:45 am
Forum: Troubleshooting
Topic: Camera not detected despite being plugged in
Replies: 19
Views: 2229

Re: Camera not detected despite being plugged in

I don't have a solution, but I have the very same problem with one of my new Zero Ws. I ordered two and equipped them with the card with the same image running Raspbian Lite with mjpg_streamer. Between the two I only changed the hostname and the static IP. One runs perfectly OK, the other one doesn'...
by Pekka
Mon Jun 17, 2019 5:07 am
Forum: Automation, sensing and robotics
Topic: Connecting a commercial accelerometer to RaspPi
Replies: 3
Views: 983

Re: Connecting a commercial accelerometer to RaspPi

We use SiliconDesigns accelerometers for various vibration measurements in traffic. They output an analogue voltage signal which needs to be digitsed. For this we use a MCP3208 ADC chip (on the Baart ADC board ), which communicates over SPI interface. For communication we use C/C++ and the BCM2835 l...
by Pekka
Mon Jul 16, 2018 4:57 am
Forum: Advanced users
Topic: PWM hardware for dimming LCD
Replies: 3
Views: 717

Re: PWM hardware for dimming LCD

The HW PWM and 3.5 mm audio jack share the same hardware and cannot both operate at the same time. So if the game generates audio on the jack, this is the cause of screen flickering.
by Pekka
Thu Sep 21, 2017 4:33 am
Forum: Advanced users
Topic: Acceleration and Impact Sensing with the Pi 3
Replies: 4
Views: 1644

Re: Acceleration and Impact Sensing with the Pi 3

We use a similar system for measuring accelerations and other quantities on a bicycle during normal ride (described here ). It uses a MCP3208 ADC chip and is powerd from a battery pack. It works very well and can record 8 analogue inputs at 500 SPS (higher rates are possible if required). Our experi...
by Pekka
Thu Aug 17, 2017 4:19 am
Forum: General discussion
Topic: Large clock display?
Replies: 17
Views: 15528

Re: Large clock display?

Mastiff37 wrote:
Sun Nov 20, 2016 5:01 pm
I think this 1.2" one would be good enough:
https://learn.adafruit.com/adafruit-led ... t-backpack
Anyone know if there software support for this device for raspberry pi?
Here is a set of C programs to drive the Adafruit display: https://github.com/FSKMTM/7-segment-LED
by Pekka
Mon Feb 20, 2017 5:47 am
Forum: C/C++
Topic: Read analog inputs at 4kHz
Replies: 14
Views: 2543

Re: Read analog inputs at 4kHz

This might provide a start:
viewtopic.php?f=37&t=170122
by Pekka
Wed Jan 04, 2017 7:24 am
Forum: Automation, sensing and robotics
Topic: RPi-based data acquisition for bicycles
Replies: 0
Views: 400

RPi-based data acquisition for bicycles

Here's a link to an article about using a Raspberry Pi with an ADC as a battery powered medium-speed data logger used on human-powered vehicles: https://authors.elsevier.com/a/1UJQBxsQZykMf The setup was devised out of a need for a device able to sample analogue output sensors on vehicles without on...
by Pekka
Thu Dec 08, 2016 6:35 am
Forum: General discussion
Topic: RPi in automotive radar research
Replies: 3
Views: 1461

Re: RPi in automotive radar research

Thank you very much for making that paper available, I was interested to read it! I look forward to a time when this type of sensor is more available for the hobbyist market, if that ever happens. Gladly. The CFP was actually published on this forum ( https://www.raspberrypi.org/forums/viewtopic.ph...
by Pekka
Wed Dec 07, 2016 5:45 am
Forum: General discussion
Topic: RPi in automotive radar research
Replies: 3
Views: 1461

Re: RPi in automotive radar research

Universal Safety Distance Alert Device for Road Vehicles http://www.mdpi.com/2079-9292/5/2/19/htm [...] The device is intended to be mounted on the rear of a vehicle. It uses radar as the primary distance sensor, assisted with a GPS receiver for velocity measurement. A Raspberry Pi single-board com...
by Pekka
Wed Dec 07, 2016 5:36 am
Forum: Automation, sensing and robotics
Topic: Looking for a radar/radio based rangefinder
Replies: 16
Views: 10477

Re: Looking for a radar/radio based rangefinder

Thanks for a very interesting link. It does seem like the distributors are of the "give us a call and we'll talk" variety. That means most of us Pi forum guy's companies/pocketbooks aren't big enough :-( Well, they were quite supportive when we were inquiring about their products, eventhough we cle...
by Pekka
Tue Dec 06, 2016 8:31 am
Forum: Automation, sensing and robotics
Topic: Looking for a radar/radio based rangefinder
Replies: 16
Views: 10477

Re: Looking for a radar/radio based rangefinder

I'm searching for a radar based rangefinder that would work up to 50m... Anybody used anything in the past? Or has anybody seen how to utilize an automotive sensor? Here is a scientific article on the topic: http://www.mdpi.com/2079-9292/5/2/19/htm We used this radar sensor with the manufacturer-pr...
by Pekka
Mon Aug 22, 2016 12:24 pm
Forum: C/C++
Topic: Sampling from ADC on SPI
Replies: 3
Views: 1269

Re: Sampling from ADC on SPI

How are you populating the timer struct? I assume it's using ftime? Is it fair to assume that timestamp_msec and next_timestamp_msec are both declared as long long ints? Yes, both assumptions are correct. It looks like a pure "busy wait" polling approach - given that you only have to worry about 4m...
by Pekka
Fri Aug 19, 2016 8:53 am
Forum: C/C++
Topic: Sampling from ADC on SPI
Replies: 3
Views: 1269

Sampling from ADC on SPI

Hello, I'm doing sampling from a MCP3208 ADC on SPI using the bcm2835 library to communicate with the chip. The target is to have the time interval of 4 ms to sample all 8 channels. I use a Raspberry Pi model B with the PREEMPT RT patched kernel. The process execution priority is set in the code lik...
by Pekka
Tue Sep 29, 2015 4:33 am
Forum: Deutsch
Topic: Vibrationsmessung mit Kistler 8772
Replies: 1
Views: 728

Re: Vibrationsmessung mit Kistler 8772

Hallo, wenn der Kistler eine version mit Spannungsausgang ist und die Vibrationsfrequenz nicht zu hoch, dann kann ich die Baart ADC Board ( https://www.raspberrypi.org/forums/viewtopic.php?f=93&t=78551 ) empfehlen. Wir verwenden sie für verschiedene Beschleuningungsmessungen (z. B. Strassen-induzier...
by Pekka
Fri May 30, 2014 5:39 pm
Forum: Troubleshooting
Topic: Force HDMI mode stopped working
Replies: 21
Views: 5623

Re: Force HDMI mode stopped working

Can you run rpi-update and confirm this works without hdmi_force_mode=1 It does. pekka@vadelma:~$ tvservice -s state 0x12001a [HDMI CEA (4) RGB lim 16:9], 1280x720 @ 60.00Hz, progressive pekka@vadelma:~$ tvservice -m CEA Group CEA has 15 modes: mode 1: 640x480 @ 60Hz 4:3, clock:25MHz progressive mo...
by Pekka
Fri May 30, 2014 11:42 am
Forum: Troubleshooting
Topic: Force HDMI mode stopped working
Replies: 21
Views: 5623

Re: Force HDMI mode stopped working

I can confirm that setting hdmi_force_mode=1 restores the behaviour before the update.

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