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by BBUK
Thu Jun 27, 2019 9:02 am
Forum: Automation, sensing and robotics
Topic: A Tower Bell "pullometer"
Replies: 3
Views: 465

Re: A Tower Bell "pullometer"

Hi blimpyway. I know that others who have tried this have thought exactly that. I decided not to follow that route because the scales (however implemented) would have to fit above the sally (so as to not interfere with the ringing action) and as the tail end of the rope is supported by the ringer du...
by BBUK
Tue Jun 25, 2019 5:20 pm
Forum: Automation, sensing and robotics
Topic: A Tower Bell "pullometer"
Replies: 3
Views: 465

Re: A Tower Bell "pullometer"

Hi all. I am about to release a second version of this device. There are lots of changes between the first and second version but most of these will be of interest to bell ringers. What will be of more general interest here is what I have done regarding the IMU and powering the unit. On the IMU, I w...
by BBUK
Thu Jun 20, 2019 11:15 pm
Forum: General discussion
Topic: Drug testing using Raspberry Pi
Replies: 20
Views: 1045

Re: Drug testing using Raspberry Pi

I love coming up with names for stuff.

DoPi (dopey)
High Pive

If I knew what's being tested for and how the test is to work, I'm sure I can think of a few more just as bad!

BBUK
by BBUK
Tue May 21, 2019 6:13 pm
Forum: C/C++
Topic: SPI Interface Modificatoins
Replies: 2
Views: 933

Re: SPI Interface Modificatoins

@anonab Doing what you what should be possible by introducing a function in your code that replicates one of the ones in the bcm2835 library but with minor changes to lengthen the SPI CS. Have a look at the bcm2835_spi_transfernb function here: https://github.com/janne/bcm2835/blob/master/bcm2835.c ...
by BBUK
Mon May 20, 2019 8:21 am
Forum: C/C++
Topic: mpu6050 with kalman filter
Replies: 10
Views: 6620

Re: mpu6050 with kalman filter

Hi where can I see the changes? As it doesnt show a commit in the repo right now @bbuk
https://github.com/BBUK/Bell-Boy/commit ... cb8c91b7b9
by BBUK
Mon Apr 15, 2019 5:24 pm
Forum: C/C++
Topic: mpu6050 with kalman filter
Replies: 10
Views: 6620

Re: mpu6050 with kalman filter

Hello just a quick question as I have also implemented the algorithm and you are converting the gyro values from deg2rad and multiplying the g0 factor to the acc values. In the article its never mentioned or have I missed it somewhere? The class implemented in the dcm_imu repository says that it us...
by BBUK
Wed Nov 21, 2018 3:20 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: BNO080 Integration (Hillcrest FSM300)
Replies: 5
Views: 3631

Re: BNO080 Integration (Hillcrest FSM300)

Hi all. Perhaps I can save someone a bit of time. I have the BNO080 working very well over SPI. Code is in the "old" directory here https://github.com/BBUK/Bell-Boy , specifically BNO080.h and grabber.c. Whilst the latter file is really specific for my use case (monitoring a rotating tower bell), mu...
by BBUK
Tue Oct 09, 2018 8:51 pm
Forum: HATs and other add-ons
Topic: BNO080 gyro-integrated rotation vector pitch data incorrect
Replies: 2
Views: 2347

Re: BNO080 gyro-integrated rotation vector pitch data incorrect

In case it helps anyone, I am working on a BNO080 implementation at the moment. It's not finished but I am able to communicate with the device over SPI and have written code designed for my use case but which I think will have a fair few routines of more general application. It uses the excellent bc...
by BBUK
Fri Jul 06, 2018 2:21 pm
Forum: Advanced users
Topic: performance - using p3b+ as wlan router
Replies: 10
Views: 1558

Re: performance - using p3b+ as wlan router

This may sound a little strange given the comments above but I had a similar problem. I found it was caused by the DHCP server on the Pi attempting to give IP addresses over all interfaces rather than just wlan0. Try configuring whichever DCHP server you are using to only apply IP addresses over wla...
by BBUK
Fri May 04, 2018 8:55 am
Forum: Advanced users
Topic: Script for changing raspberry pi hostname during boot sequence
Replies: 4
Views: 846

Re: Script for changing raspberry pi hostname during boot sequence

The only time I have have seen this error is by pasting text into a SSH terminal window from Windows notepad. It was caused by DOS-style line endings. Try converting the line endings to Unix style. Loads of ways of doing this (dos2unix for example). This perl one-liner also works: perl -pi -e 's/\r\...
by BBUK
Thu May 03, 2018 1:26 pm
Forum: Advanced users
Topic: Calling C from Python
Replies: 1
Views: 539

Re: Calling C from Python

Hi Rob.

Although it was a bit of a faff at first, I found building C extensions to be the best route. The two references I used most were:

https://docs.python.org/2/extending/extending.html (there is a similar page for Python3)

http://dfm.io/posts/python-c-extensions/

Have fun

BBUK
by BBUK
Wed Mar 28, 2018 4:28 pm
Forum: C/C++
Topic: mpu6050 with kalman filter
Replies: 10
Views: 6620

Re: mpu6050 with kalman filter

Just a little follow up to anyone that is trying to click the link I posted above - it won't work and the solution has developed. The released version of the code combines the data from two MPU6050s and pushes that to an extended Kalman filter. The main part of the code is now in the "grabber.c" fil...
by BBUK
Fri Mar 23, 2018 4:53 pm
Forum: Automation, sensing and robotics
Topic: A Tower Bell "pullometer"
Replies: 3
Views: 465

A Tower Bell "pullometer"

Hi all. A write-up of my latest Pi project which is a device to aid those learning (and those teaching others to learn) the art of tower bell ringing. It requires a lot of practice to do well. It is true that, fundamentally, you are just pulling on a rope (called a sally in the parlance) but you hav...
by BBUK
Wed Feb 28, 2018 4:53 pm
Forum: Advanced users
Topic: Bluetooth RFCOMM Server not working when using SystemD
Replies: 2
Views: 383

Re: Bluetooth RFCOMM Server not working when using SystemD

I see that the daemon uses stdout. I am not sure where that will end up when executed via systemd and your daemon could well be hanging at any stdout writes. Have you tried the daemon code in a form that does not use stdout (no daemon would normally be attached to a terminal)? As a quick and dirty t...
by BBUK
Wed Feb 07, 2018 2:16 pm
Forum: C/C++
Topic: mpu6050 with kalman filter
Replies: 10
Views: 6620

Re: mpu6050 with kalman filter

Have a look at this file in one of my repos https://github.com/BBUK/Bell-Boy/blob/master/bb_dcmimu/bb_dcmimu.c . Specifically the calculate function. This implements an EKF from https://github.com/hhyyti/dcm-imu with what I found to be really stunning results for my use case. It is not for the MPU60...
by BBUK
Mon Aug 07, 2017 2:31 pm
Forum: Advanced users
Topic: Using an adxl345 accelerometer to detect vibrations within specific frequency range
Replies: 1
Views: 1601

Re: Using an adxl345 accelerometer to detect vibrations within specific frequency range

Howdy. I have been messing around *a lot* with accelerometers recently but for a different application. The way I would tackle this is, in theory, straightforward - take samples from the ADXL345 applying a suitable low pass filter (it looks like the device can do this itself) then apply the samples ...
by BBUK
Tue Aug 01, 2017 3:47 pm
Forum: General discussion
Topic: My Raspberry Pi 3 Speed
Replies: 8
Views: 1194

Re: My Raspberry Pi 3 Speed

The OP may well be connecting over wifi and wifi throughput increases significantly in the absence of noisy appliances like the "old vacuum" (or in my case the microwave oven). I bet that's what he is experiencing.

BBUK
by BBUK
Fri Jul 21, 2017 1:39 pm
Forum: General discussion
Topic: WANTED: Wifi testers!
Replies: 12
Views: 1853

Re: WANTED: Wifi testers!

Heater, I only had a quick scan myself but the TL;DR seems to be that some IP packets going through the brcmfmac driver have a priority setting. When that setting is at 0x10 or 0x08 some packets are silently lost, causing wifi issues. The PR (now merged with 4.12) forces the setting to 0x00. This is...
by BBUK
Fri Jul 21, 2017 1:15 pm
Forum: General discussion
Topic: WANTED: Wifi testers!
Replies: 12
Views: 1853

Re: WANTED: Wifi testers!

Happy to help.

Unless you have any objections, I'll test on 4.9 and the Zero W as that matches a particular use case that I am looking to use internal wifi for. I can apply the change directly to the 4.9 source (it's only one line!)

BBUK
by BBUK
Tue May 09, 2017 3:50 pm
Forum: Automation, sensing and robotics
Topic: Poor man's ADC
Replies: 4
Views: 1138

Re: Poor man's ADC

Thanks Joan (and triphil). I suppose I cannot argue much against the ease of a solution that uses a cap and a resistor rather than two resistors but for monitoring battery voltage there is a problem with timing the charging of a cap in that we can't have the cap charging much above 3.3V to protect t...
by BBUK
Tue May 09, 2017 11:18 am
Forum: Automation, sensing and robotics
Topic: Poor man's ADC
Replies: 4
Views: 1138

Poor man's ADC

Hi all. I have a RPi zero powered through a PP3 9v battery and a switcher to take the voltage down. I would like to monitor the remaining power of that battery by measuring its voltage. A quick and easy way to do this would be with a resistive divider connected directly to a GPIO pin. From what I ca...
by BBUK
Wed Feb 08, 2017 1:56 pm
Forum: General discussion
Topic: How to connect a SDR to a pi3 then wirelessly access it?
Replies: 6
Views: 1815

Re: How to connect a SDR to a pi3 then wirelessly access it?

I think Snapcast would be a good solution for this https://github.com/badaix/snapcast . As long as the output from the SDR software can be piped to a file then the Snapcast server can pick it up and send it over the network to a device that has a Snapcast client running on it (there is a client for ...
by BBUK
Tue Dec 13, 2016 11:31 am
Forum: Python
Topic: why does Pygame script wait for ESC key press on auto start
Replies: 3
Views: 1153

Re: why does Pygame script wait for ESC key press on auto st

Hi windy54.

Your problem does not look exactly like one that I was experiencing but try my solution here: http://stackoverflow.com/questions/1703 ... it-display

Have fun

BBUK
by BBUK
Sun Oct 09, 2016 5:55 am
Forum: Graphics, sound and multimedia
Topic: Virtual Window with Parallax
Replies: 2
Views: 747

Re: Virtual Window with Parallax

I hadn't posted any code as I just have a slow updating proof of concept that will need a load of work. It was more of a generic, "Have fun with life" :lol:
by BBUK
Sat Oct 08, 2016 4:00 pm
Forum: Graphics, sound and multimedia
Topic: Virtual Window with Parallax
Replies: 2
Views: 747

Virtual Window with Parallax

Hi all. I have been playing around with something this afternoon. I had an idea to convert a TV to a virtual window using a Pi. The nice bit is that the display changes as the viewer moves his/her head to simulate what would happen in a real window (you can see more of the outside when you are close...

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