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by Mortimer
Sun Dec 01, 2019 10:53 pm
Forum: Other projects
Topic: Detect negative voltage on GPIO?
Replies: 6
Views: 261

Re: Detect negative voltage on GPIO?

Surely it would be far easier to feed the output signal (Q) of the chip to your GPIO as is, and let your software work out when the state of the GPIO changes from low to high and high to low?
by Mortimer
Tue Jul 09, 2019 9:13 pm
Forum: Troubleshooting
Topic: Trouble Getting HDMI Output From RPi4
Replies: 50
Views: 9969

Re: Trouble Getting HDMI Output From RPi4

@Mortimer - It turns out I already had a uHDMI socket -> plug extension cable, so I was finally able to connect my Pi4 up to my lapdock. I already had the SD card configured to use HDMI and VGA666 on the GPIO pins, so I plugged it in and booted. i didn't have any problems at all. I had an extended ...
by Mortimer
Sun Jun 30, 2019 7:06 pm
Forum: Troubleshooting
Topic: Trouble Getting HDMI Output From RPi4
Replies: 50
Views: 9969

Re: Trouble Getting HDMI Output From RPi4

I am having trouble getting HDMI output from my new RPi4. I am able to get to it via SSH, so would appear to be working. The display (Motorola Atrix Lapdock) is not complaining that there is no signal, which it does if I switch the connection to the HDMI-1 port. So I presume there is a signal there...
by Mortimer
Thu Jun 27, 2019 10:13 pm
Forum: Troubleshooting
Topic: Trouble Getting HDMI Output From RPi4
Replies: 50
Views: 9969

Re: Trouble Getting HDMI Output From RPi4

Sort of comforting to know that I am not alone with this problem. Would be nice to find a solution. I wish the RPi had a feature like my Apple TV. A button combination puts it into a mode where it can be stepped through all available display modes one-by-one by clicking a button. Naturally you stop ...
by Mortimer
Thu Jun 27, 2019 8:34 pm
Forum: Troubleshooting
Topic: Trouble Getting HDMI Output From RPi4
Replies: 50
Views: 9969

Trouble Getting HDMI Output From RPi4

I am having trouble getting HDMI output from my new RPi4. I am able to get to it via SSH, so would appear to be working. The display (Motorola Atrix Lapdock) is not complaining that there is no signal, which it does if I switch the connection to the HDMI-1 port. So I presume there is a signal there,...
by Mortimer
Fri May 24, 2019 9:08 am
Forum: Graphics, sound and multimedia
Topic: FBI is hardware accelerated?
Replies: 12
Views: 899

Re: FBI is hardware accelerated?

Even if it isn't actually any faster, presumably it is still beneficial to use it if doing lots of conversions so the ARM remains free to do other things that the GPU can't?
by Mortimer
Wed Apr 17, 2019 9:35 am
Forum: Python
Topic: How to save GPS Data to a text file?
Replies: 12
Views: 838

Re: How to save GPS Data to a text file?

It probably relates to the OP's first port to the forum... https://www.raspberrypi.org/forums/viewtopic.php?f=32&t=234357&p=1433628#p1433628 They are probably still using an Adafruit Ultimate GPS Breakout. I assume by this question they have managed to get the GPS board working, if so it would have ...
by Mortimer
Sun Apr 14, 2019 10:52 am
Forum: Beginners
Topic: Convert NMEA sentence Lat and Lon to Decimal Degrees
Replies: 4
Views: 13441

Re: Convert NMEA sentence Lat and Lon to Decimal Degrees

My word! How silly of me. Amazing it stood for so long undetected! Corrected (for what it's worth): So... Lat : 3137.36664 becomes 31 degrees and 37.26664 seconds = 31 + 37.36664/60 = 31.6227773 Lon : 00212.21149 becomes 2 degrees and 12.21149 seconds = 2 + 12.21149/60 = 2.20352483 So as latitude is...
by Mortimer
Wed Mar 13, 2019 12:48 pm
Forum: Beginners
Topic: Electric pulse scanner
Replies: 8
Views: 656

Re: Electric pulse scanner

Yup, what Brandon said. With a new contact block for the switch available for only a handful of £'s (or €'s or $'s) it's a no brainer really. https://uk.rs-online.com/web/p/contact-blocks-light-blocks/3310473/ All that is left is whether or not you can legally modify the equipment, i.e. do local reg...
by Mortimer
Wed Feb 27, 2019 9:58 am
Forum: HATs and other add-ons
Topic: Motorola Lapdock Atrix with the Pi
Replies: 16
Views: 4009

Re: Motorola Lapdock Atrix with the Pi

I have an Atrix lapdock, and in my experience: RPi 2B worked reliably, powered from the lapdock, even without a USB power lead connected from the lapdock to the RPi power inlet. I.e. powered entirely via backfeed power down the USB data connection. However this only worked if using the USB socket on...
by Mortimer
Tue Feb 12, 2019 12:44 pm
Forum: Off topic discussion
Topic: Order a special request Raspberry Pi :?:
Replies: 68
Views: 5153

Re: Order a special request Raspberry Pi :?:

I was there at VMWorld 2018 in Las Vegas when they demonstrated ESXi running on a Raspberry Pi. At the time they stated that this wasn't done because the Raspberry Pi was a realistic platform to run a hypervisor, but because if they could get it running on a Pi then any ARM based board becomes a pos...
by Mortimer
Fri Feb 08, 2019 1:12 pm
Forum: Gaming
Topic: Commodore PET Mini
Replies: 11
Views: 1205

Re: Commodore PET Mini

Looks interesting. I like the look of the website too, but I do wonder why the "What You'll Need" page has pink links for the item names, that simply link back to the top of the page rather than manufacturer or supplier pages for the items in question?
by Mortimer
Tue Feb 05, 2019 12:18 pm
Forum: Automation, sensing and robotics
Topic: Seeking guidance with powering motors
Replies: 19
Views: 1260

Re: Seeking guidance with powering motors

Brushed motors connected in series is not ideal either. The current passing through a brushed motor is very choppy, and this passes through the next motor which adds its own choppiness and so on. They may turn, but I would expect torque at each motor to be way down on what it can do by itself on its...
by Mortimer
Wed Jan 23, 2019 2:54 pm
Forum: General discussion
Topic: Control Fan by switching USB port on and off
Replies: 22
Views: 1507

Re: Control Fan by switching USB port on and off

You'll need snubbers on those motors, to 'snub' the back EMF from the motors when they are turned off. Otherwise you'll get voltage spikes going back into the 5V supply rail.

It might also be preferable for the 5V supply to come directly from the PSU, rather than via the RPi.
by Mortimer
Mon Jan 21, 2019 1:17 pm
Forum: Automation, sensing and robotics
Topic: 2 LED wiring
Replies: 11
Views: 898

Re: 2 LED wiring

You can use one resistor if only one LED will be on at a time . Anode of each LED to their GPIOs. Cathodes of LEDs and one end of resistor all joined together. Other end of resistor to ground. he wouldn't be able to use the circuit as shown even in those circumstances. The right hand LED is depicte...
by Mortimer
Tue Nov 27, 2018 1:31 pm
Forum: General discussion
Topic: Flyback Diodes - Solenoid Valves
Replies: 9
Views: 985

Re: Flyback Diodes - Solenoid Valves

If using a relay then I'd say there was little need for the flyback diode. The potential on one contact of the relay goes up, but that's not going to cause any grief (unless it could get high enough to arc). Surely there will be an arc between the relay contacts every time the contacts are opened (...
by Mortimer
Thu Nov 22, 2018 10:49 am
Forum: Troubleshooting
Topic: Try to run a Python script without luck...
Replies: 6
Views: 690

Re: Try to run a Python script without luck...

Alternatively, if you're using WinSCP to copy the file to the RPi, the conversion will be done there too, but you may need to make sure the transfer mode is set to "Text", or if it is set to "Automatic" that the "Transfer following files in text mode:" field contains the file extensions for the file...
by Mortimer
Thu Nov 22, 2018 10:17 am
Forum: Troubleshooting
Topic: Try to run a Python script without luck...
Replies: 6
Views: 690

Re: Try to run a Python script without luck...

Yup, had to do a similar thing just a few minutes ago whilst writing a shell script to run on an ESXi server in Notepad++. With the file open, select "Edit" > "EOL Conversion" > "Unix (LF)". I believe Notepad++ will remember that setting for the file, so it shouldn't be necessary to do that again fo...
by Mortimer
Thu Nov 22, 2018 10:09 am
Forum: Troubleshooting
Topic: relay or led - fluctuating
Replies: 7
Views: 1363

Re: relay or led - fluctuating

I wouldn't mind betting on the flowmeter actually accelerating when the gas is blasted through it. I reckon the impeller inside will spin much more freely in a gaseous flow, without the viscosity of the fluid to slow it down. So basically when the gas solenoid valve is opened until possible several ...
by Mortimer
Wed Nov 21, 2018 7:01 pm
Forum: Troubleshooting
Topic: relay or led - fluctuating
Replies: 7
Views: 1363

Re: relay or led - fluctuating

I guess - change the code to ignore the flowmeter pulses after the pour has completed.
by Mortimer
Wed Nov 21, 2018 11:30 am
Forum: Troubleshooting
Topic: relay or led - fluctuating
Replies: 7
Views: 1363

Re: relay or led - fluctuating

Does the flow meter stop spinning and sending pulses when the solenoid is turned off?

I suspect that it may be that when the solenoid closes and the liquid is drained past the flow sensor, the sensor spins for a few more seconds, giving you more counts than you expect.
by Mortimer
Tue Nov 20, 2018 6:48 am
Forum: Troubleshooting
Topic: relay or led - fluctuating
Replies: 7
Views: 1363

Re: relay or led - fluctuating

My guess based on what I can see here is that there is not enough power for the cleaning solenoid to open properly.

Does the program run correctly without the solenoid connected?
by Mortimer
Fri Nov 02, 2018 12:25 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 8991

Re: Detect current on Raspberry pi

So you think just turning the mic gain down will be enough?

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