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by Pekka
Mon Jun 17, 2019 5:07 am
Forum: Automation, sensing and robotics
Topic: Connecting a commercial accelerometer to RaspPi
Replies: 3
Views: 519

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: 407

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: 1196

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: 16
Views: 10570

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: 1906

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: 317

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: 1188

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: 1188

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: 8355

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: 8355

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: 985

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: 985

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: 618

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: 4329

Re: Force HDMI mode stopped working

Can you run rpi-update and confirm this works without hdmi_force_mode=1 It does. [email protected]:~$ tvservice -s state 0x12001a [HDMI CEA (4) RGB lim 16:9], 1280x720 @ 60.00Hz, progressive [email protected]:~$ 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: 4329

Re: Force HDMI mode stopped working

I can confirm that setting hdmi_force_mode=1 restores the behaviour before the update.
by Pekka
Thu May 29, 2014 5:14 am
Forum: Troubleshooting
Topic: Force HDMI mode stopped working
Replies: 21
Views: 4329

Re: Force HDMI mode stopped working

If I do tvservice -e "CEA 4 HDMI" after bootup I only get a black screen in X and a garbled-up console.
I would really appreciate if someone explained what's going on and how to revert the behaviour to what it was before it got broken.
by Pekka
Mon May 26, 2014 6:46 pm
Forum: Troubleshooting
Topic: Force HDMI mode stopped working
Replies: 21
Views: 4329

Force HDMI mode stopped working

Hello, after last firmware update (c889591258e0eafeae94915101cc3a5f20c6080a via rpi-update) my Raspberry Pi started ignoring the hdmi_mode and hdmi_group settings in /boot/config.txt. It is (as it has been for the last year or so) connected to a LG LN5758 TV via HDMI and happily worked in HDMI CEA m...
by Pekka
Thu Jul 11, 2013 12:09 pm
Forum: Automation, sensing and robotics
Topic: Security Camera That Emails Files
Replies: 5
Views: 2720

Re: Security Camera That Emails Files

txt3rob wrote:it would also be worth while emailing a link for the live streaming also to show you real time what is going on
Yes. In my case a MJPEG stream is embeded in the main.html file.
by Pekka
Tue Jul 09, 2013 8:09 am
Forum: Automation, sensing and robotics
Topic: Security Camera That Emails Files
Replies: 5
Views: 2720

Re: Security Camera That Emails Files

I have Wheezy and Motion installed correctly on my Pi. I want to set up my Pi as a security camera that detects motion, and takes snapshots every couple seconds or so that it detects motion and sends it to my GMail. A detailed tutorial would be great. Thanks! You can use imgcmp from th libjasper pa...

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