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by davidcoton
Tue Jan 22, 2019 10:46 am
Forum: General discussion
Topic: Raspberry PI for Macbook Pro
Replies: 4
Views: 46

Re: Raspberry PI for Macbook Pro

You can use the Mac as a terminal for the Pi, using SSH (command line) or VNC (GUI) over WiFi or Ethernet.
Plenty of info in the Documentation section, or search the site.
by davidcoton
Tue Jan 22, 2019 10:42 am
Forum: Assistive technology and accessibility
Topic: Project for visually impaired
Replies: 1
Views: 14

Re: Project for visually impaired

Is this an academic project, or for a particular user you know, or both? Break the project down into parts, then into smaller parts. Work out how the hardware fits together and how you drive each part. Identify the libraries for number recognition and speech generation. Get the software working sepa...
by davidcoton
Tue Jan 22, 2019 10:37 am
Forum: Advanced users
Topic: Shoot flash LED with GPIO in long exposure photos
Replies: 3
Views: 67

Re: Shoot flash LED with GPIO in long exposure photos

driving a real flash unit (should) be done with an additional transistor to short the firing leads on the flash; the GPIO just serving as the gate. Be aware that some (mainly older) flash guns have Pi-killing person-jolting high voltages on the shoe contacts, even modern ones may use more than the ...
by davidcoton
Tue Jan 22, 2019 10:30 am
Forum: General discussion
Topic: Features for future Pi, voltage/current reporting.
Replies: 18
Views: 320

Re: Features for future Pi, voltage/current reporting.

What possible use does it have? It's like reading the cpu temperature, what can you do if you don't like the numbers? If you don't like the numbers you change the way you work so that there is a decreased risk of something going wrong. For example if someone is using a power bank to power a portabl...
by davidcoton
Tue Jan 22, 2019 10:24 am
Forum: Beginners
Topic: USB communication with Pi Zero
Replies: 4
Views: 83

Re: USB communication with Pi Zero

You can use a hub, or any "B" version of the Pi (B, B+, 2B, 3B, 3B+) which all have multiple USB sockets.
It won't be "simultaneous", you will have to write code to read the input then write the output to a different port.
by davidcoton
Tue Jan 22, 2019 10:20 am
Forum: Beginners
Topic: RPi Pull-Up Resistor Termination?
Replies: 3
Views: 71

Re: RPi Pull-Up Resistor Termination?

rpdom wrote:
Tue Jan 22, 2019 6:51 am
If you are not using a pin, it doesn't really matter if it is floating or not.
While that is true in this case, it is good practice to terminate unused inputs to logic systems. In fact many pulls are set by default:
Most GPIOs have a default pull applied.
More details here.
by davidcoton
Tue Jan 22, 2019 10:13 am
Forum: General discussion
Topic: SD Card re instertment
Replies: 2
Views: 35

Re: SD Card re instertment

Work through The Boot Problems Sticky first.
by davidcoton
Mon Jan 21, 2019 11:58 pm
Forum: Troubleshooting
Topic: OpenVPN can't write logfile to home folder
Replies: 26
Views: 384

Re: OpenVPN can't write logfile to home folder

taylorkh wrote:
Mon Jan 21, 2019 11:19 pm
My wife says computers have a mind of their own. Perhaps that is true :mrgreen:
The trouble with computers is that they do what you told them -- not what you think you told them. :evil:
by davidcoton
Mon Jan 21, 2019 11:52 pm
Forum: Beginners
Topic: navigation system
Replies: 10
Views: 250

Re: navigation system

we don't how start it. We just need a source code to modify. I think you need to talk to your supervisor. Something is wrong with the course if they have not taught you how to analyse the problem, design the solution and write the code. [HINT: Break it down into small sections, conquer one section ...
by davidcoton
Mon Jan 21, 2019 11:49 pm
Forum: Beginners
Topic: RPi Pull-Up Resistor Termination?
Replies: 3
Views: 71

Re: RPi Pull-Up Resistor Termination?

The internal ones are OK.
by davidcoton
Mon Jan 21, 2019 10:40 pm
Forum: Beginners
Topic: Act as a printer
Replies: 2
Views: 49

Re: Act as a printer

Talk to your Fire system supplier/maintainer. You need to be absolutely sure that connecting a Pi will not affect the fire alarm operation or certification.
by davidcoton
Mon Jan 21, 2019 6:14 pm
Forum: General discussion
Topic: Features for future Pi, voltage/current reporting.
Replies: 18
Views: 320

Re: Features for future Pi, voltage/current reporting.

DarkPlatinum wrote:
Mon Jan 21, 2019 6:00 pm
I dont think you can measure the amperage drawn by the USB ports (or can you?)
You can use a Charge Doctor on the input or on any single USB output.
AFAIK Raspbian logs an error when the total USB output current exceeds the limit (1A2 on most Pi models).
by davidcoton
Mon Jan 21, 2019 6:07 pm
Forum: Beginners
Topic: Cost effective project
Replies: 11
Views: 203

Re: Cost effective project

However, a magnet, reed switch or hall sensor requires the two parts to come very close to each other. (eg: magnet needs to be within 13mm) Is there a way to accomplish the same, but have more space between the two parts? You could use an opto-detector: IR LED and phototransistor with suitable opti...
by davidcoton
Mon Jan 21, 2019 5:57 pm
Forum: Beginners
Topic: navigation system
Replies: 10
Views: 250

Re: navigation system

sky12 wrote:
Mon Jan 21, 2019 2:06 pm
Hi everyone, we are working on something like autopilot wheelchair. Do you mind if ask some source codes in python for autopilot system?
Isn't part of the project for you to write the code? If not, what is the thesis actually about?
by davidcoton
Mon Jan 21, 2019 5:53 pm
Forum: General discussion
Topic: 64-bit operating system
Replies: 333
Views: 34643

Re: 64-bit operating system

I realize that my application is a very small percentage of RPis, and that creating a 64-bit version of Raspbian is a huge job. But it sure would be more satisfying. It's a "want" not a "need." [dangerous mode] PREDICTION 64 bit Raspbian will happen. Possibly unofficially before officially. We just...
by davidcoton
Mon Jan 21, 2019 5:40 pm
Forum: General discussion
Topic: copyright/patent
Replies: 7
Views: 243

Re: copyright/patent

From the FAQ: https://www.raspberrypi.org/documentation/faqs/#commercial Only the RPi ZERO models can do 'gadget' mode. RPi zero purchases are limited to 1 per order. There are no one per order limitation buying Raspberry Pi Zero WH (with headers) model. I believe bulk purchase of other Zero models...
by davidcoton
Mon Jan 21, 2019 5:36 pm
Forum: General discussion
Topic: Features for future Pi, voltage/current reporting.
Replies: 18
Views: 320

Re: Features for future Pi? (suggestion)

Current measurement would be quite difficult, would require a load resister etc and that would just increase the power consumption. IIRC, I'm not an expert with electronics. The increase in consumption should be negligible, however it would add some voltage drop on the incoming 5V, just where we do...
by davidcoton
Mon Jan 21, 2019 1:37 pm
Forum: Beginners
Topic: Cost effective project
Replies: 11
Views: 203

Re: Cost effective project

How would you approach the fact that ultrasonic sensor would move with the lift but the power supply is on the fixed part of the lift? I want this to be as robust/solid as possible and I think that will be a weak spot of the set-up. I would use a non-contact sensor (three type mentioned by others h...
by davidcoton
Mon Jan 21, 2019 1:24 pm
Forum: General discussion
Topic: computer power supply
Replies: 25
Views: 707

Re: computer power supply

The msmf250/x, which is the polyfuse on the Pi, has a solderability rating. That rating is, according to the data sheet, J-STD-002, which can be found here: http://www.ipc.org/TOC/J-STD-002D.pdf According to the document, soldering should take no longer than five seconds. Thanks, that's interesting...
by davidcoton
Mon Jan 21, 2019 10:20 am
Forum: Beginners
Topic: Cost effective project
Replies: 11
Views: 203

Re: Cost effective project

You can go two ways: Wired sensors. Put a sensor on each lift and wire it to a central Pi. You would need a suitably tough cable and usable safe cable routes to each lift. Wireless. Use a Pi0WH at each lift. As long as you already have power to each lift so you can run a Pi PSU, this will almost cer...
by davidcoton
Mon Jan 21, 2019 10:11 am
Forum: Beginners
Topic: Connecting two Pis via GPIO
Replies: 3
Views: 81

Re: Connecting two Pis via GPIO

You can't do that. There are ways of connecting just a few pins of the GPIO to allow you to write programs where the Pis work together. Or they can communicate over WiFi.

What are you trying to achieve?
by davidcoton
Mon Jan 21, 2019 9:57 am
Forum: General discussion
Topic: DIY Webcam in Finland
Replies: 17
Views: 351

Re: DIY Webcam in Finland

Good point about using a battery more appropriate for the type of load. Which kind would be more appropriate for a low but steady drain? There are lead acid batteries designed for lower, more regular discharge. Look for "Leisure" batteries, sold for caravans and trailers. Also, check the specificat...
by davidcoton
Mon Jan 21, 2019 9:41 am
Forum: General discussion
Topic: computer power supply
Replies: 25
Views: 707

Re: computer power supply

but the polyfuse protects the pi right? It isn't indestructible. It won't last forever. One trip could be enough to make the polyfuse more of a problem than a safety device. Some users have reported the polyfuse never returns to its original resistance and as a result, causes more voltage drop afte...
by davidcoton
Sat Jan 19, 2019 11:01 pm
Forum: Troubleshooting
Topic: Boot Problems
Replies: 10
Views: 212

Re: Boot Problems

A jumper over the two 5V pins is a brilliant idea. It will not harm the board to connect the two 5V pins. I'm sure I (and others) will pass on that idea. I would recommend installing the jumper with the power disconnected, and check its position very carefully at least twice before applying power. J...
by davidcoton
Sat Jan 19, 2019 3:33 pm
Forum: Troubleshooting
Topic: Raspberry Pi 3 won't boot, red LED light only
Replies: 1
Views: 44

Re: Raspberry Pi 3 won't boot, red LED light only

Start with The Boot Problems Sticky, which will probably answer your question.

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