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by Dedward5
Wed Apr 25, 2018 3:15 pm
Forum: Troubleshooting
Topic: Vieweing python output on headless Pi (VNC Problem)
Replies: 3
Views: 266

Re: Vieweing python output on headless Pi (VNC Problem)

Thanks, So that just pipes all the screen output to a file then, thats definitely useful and relevant so ill try that. Im still interested to know if there is a VNC type approach to this as well. im not 100% sure that the pi isnt "crashing" e.g. due to momentary power-loss or very high GPIO input. I...
by Dedward5
Wed Apr 25, 2018 10:15 am
Forum: Troubleshooting
Topic: Vieweing python output on headless Pi (VNC Problem)
Replies: 3
Views: 266

Vieweing python output on headless Pi (VNC Problem)

Hi, I have a python program that Im trying to debug running "in situ" but have issues. Its a car data-logger based on pi/sense hat which runs headless in the car, every now an then it crashes (the program not the car) and I cant see any output as its not connected to a monitor etc and cant be for va...
by Dedward5
Tue May 02, 2017 4:34 pm
Forum: Automation, sensing and robotics
Topic: Erratic logging of high(ish) Hz GPIO
Replies: 6
Views: 949

Re: Erratic logging of high(ish) Hz GPIO

Joan, thanks for your continued input. I did a slightly hacky inline way to do this in the main code which ill test on the car later, but I think ill try your method at some point soon as I think its probably the most accurate and efficient.
by Dedward5
Tue May 02, 2017 12:24 pm
Forum: Automation, sensing and robotics
Topic: Erratic logging of high(ish) Hz GPIO
Replies: 6
Views: 949

Re: Erratic logging of high(ish) Hz GPIO

Hi, thanks to both of you for your help, thats stopped my going further on the thread approach which seems to be the limitation. Being a noob I dont quite understand the pigpio module that well and not in the context of multiprocessing. Does the pigpio and rpm code linked need to run separately to m...
by Dedward5
Mon May 01, 2017 10:08 pm
Forum: Automation, sensing and robotics
Topic: Erratic logging of high(ish) Hz GPIO
Replies: 6
Views: 949

Re: Erratic logging of high(ish) Hz GPIO

Hi,

The car idles around 1000 rpm and revs to 7500 rpm.

With the ECU putting out 2 pulses per revolution it would be, for example, 100hz (3000/60*2) which shouldn't really be an issue?

Thanks.
by Dedward5
Mon May 01, 2017 9:21 pm
Forum: Automation, sensing and robotics
Topic: Erratic logging of high(ish) Hz GPIO
Replies: 6
Views: 949

Erratic logging of high(ish) Hz GPIO

Hi, I have built a racing car data logger based on the Pi and a Sense hat. It works great for sense data, camera and GPS, but I have hit a snag with trying to log car RPM. I built a simple circuit that gets pulses from the ECU via the wire that feeds the Dash Tacho (2 pulses per rpm), then wrote som...
by Dedward5
Sun Feb 19, 2017 11:01 pm
Forum: Automation, sensing and robotics
Topic: Hertz to RPM car tacho problem
Replies: 11
Views: 2543

Re: Hertz to RPM car tacho problem

Sorry I realise my original post didn't have some background. Im reading the Hz from an output of the ECU to the Tacho on the dash. The manual for the ECU says the Tacho output is "12v pulse" (although the meter only reads 7.5v on the meters "max hold" setting, but that could be a meter "speed" issu...
by Dedward5
Sun Feb 19, 2017 10:55 pm
Forum: Automation, sensing and robotics
Topic: Hertz to RPM car tacho problem
Replies: 11
Views: 2543

Re: Hertz to RPM car tacho problem

Ok, I think I have stumbled on the maths required (Hours of guessing into a spreadsheet!) RPM = (TachHz x 600) xTachHz - but I dont really know why! Note that if you try this in a spreadsheet the calculated RPM values are not exactly correct, but remember that reading the dial wasn't precise,its ana...
by Dedward5
Sun Feb 19, 2017 6:46 pm
Forum: Automation, sensing and robotics
Topic: Hertz to RPM car tacho problem
Replies: 11
Views: 2543

Re: Hertz to RPM car tacho problem

Hi, I checked for DC voltage and its max 10v on startup but then stabalises at 7.5v immediatley. It then stays stable at 7.5vDC regardless of RPM. The manual saysis its a 12v pulse output so im reasonably sure the Hz thing is on the right track. Im close to getting the formula but cant quite work ou...
by Dedward5
Sun Feb 19, 2017 2:02 pm
Forum: Automation, sensing and robotics
Topic: Hertz to RPM car tacho problem
Replies: 11
Views: 2543

Hertz to RPM car tacho problem

Hi, Im making a datalogger for a racing car (non ODB based) and hit a snag understanding the tacho (RPM) signal. I was expecting a simple 1/1 or 1/4 ratio for a 4 stroke engine, but its not that simple so I cant just use one of the many hz to rpm calculators in the web etc. Using the HZ setting on a...
by Dedward5
Mon Feb 13, 2017 10:15 pm
Forum: Automation, sensing and robotics
Topic: 5v input from Car ECU Tacho signal
Replies: 7
Views: 1339

Re: 5v input from Car ECU Tacho signal

Hi, Thanks for your help, I have updated the plans based on 12v and some learning about voltage dividing with resistors. Tacho_Schematic_v2.jpg I work it out to be a 10k and a 3.3k resistor to be safe (up to 13.5v as a spike) ? Looks like I need to increase my pile of parts so ill order some stuff a...
by Dedward5
Mon Feb 13, 2017 7:53 pm
Forum: Automation, sensing and robotics
Topic: 5v input from Car ECU Tacho signal
Replies: 7
Views: 1339

Re: 5v input from Car ECU Tacho signal

OK I realised I can check the ECU manual (Emerald MDK3) and its 12v so sensible to challenge any assumption (I promise I was going to use a multi meter too! but its cold in the garage) http://www.emeraldm3d.com/media/software-manuals/Emerald%20M3DK%20Manual%20v5.pdf So ill need to step down from 12v...
by Dedward5
Mon Feb 13, 2017 7:22 pm
Forum: Automation, sensing and robotics
Topic: 5v input from Car ECU Tacho signal
Replies: 7
Views: 1339

5v input from Car ECU Tacho signal

Hi, Im looking to read the ECU output to the Tacho (RPM) on my pre-ODBII car as part of a motorsport datalogger project. I think the signal is 5v square wave and I copied this basic circuit for the start of my ideas https://www.raspberrypi.org/forums/viewtopic.php?f=45&t=22841 My circuit is attached...
by Dedward5
Fri Jan 13, 2017 11:28 am
Forum: Astro Pi
Topic: New release of Sense HAT Python library v2.2.0
Replies: 8
Views: 6533

Re: New release of Sense HAT Python library v2.2.0

Hi,

Im really struggling with this (joystick) this tread looks promising but when I try to do the manual install I get the message

ImportError: No module named setuptools

Ps im doing the manual install because the usual install method does not seem to give me the sense stick module.

Thanks,

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