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by rpdom
Sat Jul 21, 2018 7:08 am
Forum: Troubleshooting
Topic: Dead USB and Ethernet ports
Replies: 8
Views: 138

Re: Dead USB and Ethernet ports

Incorrect info, on RPis which have more than one USB Port as well as an Ethernet Port, they are all connected to a single USB2.0 Chipset, pre 3B+ it was a LAN9512/14: Is this a 3B+? If so, there are two USB hubs in the onboard chip. It looks like one pair of sockets and the second hub are connected...
by rpdom
Sat Jul 21, 2018 5:10 am
Forum: Troubleshooting
Topic: IP Address Printed on 16x2 LCD
Replies: 3
Views: 65

Re: IP Address Printed on 16x2 LCD

What does your program do if there is no IP address allocated when it runs?

It is possible that rc.local is being run before the network is ready. There is an option in raspi-config -> Boot Options -> Wait for Network at Boot that should make sure the network has been set up before running rc.local.
by rpdom
Sat Jul 21, 2018 4:52 am
Forum: Troubleshooting
Topic: PLEASE HELP!
Replies: 6
Views: 93

Re: PLEASE HELP!

Putting a Pi SD card in a Windows computer will often result in the "needs scanning and repairing" message. Ignore the message. It is incorrect. It is because Windows does not recognise the part of the card that the Pi uses. "Scanning and repairing" will break the contents of the card. Download the ...
by rpdom
Sat Jul 21, 2018 4:23 am
Forum: Troubleshooting
Topic: matplotlib installed but doesn't want to import
Replies: 3
Views: 1178

Re: matplotlib installed but doesn't want to import

I have same problem, so tried offered solution: [email protected]:~/Computer Vision Experience/Computer Vision Code/Section3/codes $ sudo apt-get install libatlas3-base Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package libatlas3-base JHP Now...
by rpdom
Fri Jul 20, 2018 10:59 am
Forum: Troubleshooting
Topic: Send Output to Composite/HDMI At Boot Time
Replies: 9
Views: 173

Re: Send Output to Composite/HDMI At Boot Time

Turn on HDMI: tvservice -p Turn on Composite: tvservice -c "PAL 4:3" (change the attributes to suit your TV. Only one output can be on at a time, so turning one on will disable the other. You can't detect if the TV is connected. If HDMI is inactive the Pi will default to composite output even if not...
by rpdom
Fri Jul 20, 2018 5:18 am
Forum: General discussion
Topic: Relay Module KY-019 5V
Replies: 196
Views: 8767

Re: Relay Module KY-019 5V

I closely watched his perhaps 50 years old ugly calculator ... There were no calculators like that 50 years ago. ... But 50 years ago Little Clive was already selling his little, pocket size calculator. So Big Clive's big, notebook size calculator must be over 50 years old. Or have I been reading G...
by rpdom
Thu Jul 19, 2018 5:17 pm
Forum: General discussion
Topic: Relay Module KY-019 5V
Replies: 196
Views: 8767

Re: Relay Module KY-019 5V

I closely watched his perhaps 50 years old ugly calculator and forgot what he was saying. There were no calculators like that 50 years ago. There were some purely mechanical ones. Some worked by pulling a lever to do the calculation. Others used electricity to drive a motor to do the work. His othe...
by rpdom
Thu Jul 19, 2018 5:00 pm
Forum: Troubleshooting
Topic: Raspberry Pi 3B+ overheating during zero activity or low activity (PiAware & Dump1090-fa Installed)
Replies: 21
Views: 435

Re: Raspberry Pi 3B+ overheating during zero activity or low activity (PiAware & Dump1090-fa Installed)

Room temperature 25.250°C
Raspi 3B+ temperature 60.686°C

Official case with lid on.

Nothing major running on it yet.
by rpdom
Thu Jul 19, 2018 4:53 pm
Forum: General discussion
Topic: RPi (Zero) in extreme temperatures experiences
Replies: 7
Views: 231

Re: RPi (Zero) in extreme temperatures experiences

W. H. Heydt wrote:
Thu Jul 19, 2018 4:48 pm
That's the Pi3B. The defaults have been: Model B, 700MHz. Model A, 700MHz, Model B+, 700MHz, Model A+, 700MHz, Pi2B (both variants), 900MHz, Pi0/Pi0W, 1GHz, Pi3B, 1.2GHz, Pi3B+, 1.4GHz.
IIRC, when I got my first Pi 1B (May 2012), the default was 600MHz, later raised to 700.
by rpdom
Thu Jul 19, 2018 7:05 am
Forum: General programming discussion
Topic: What Does Hiding the Details of I/O in Library Calls Teach?
Replies: 63
Views: 1384

Re: What Does Hiding the Details of I/O in Library Calls Teach?

bensimmo wrote:
Thu Jul 19, 2018 6:32 am
That's when you get Orangutans.
In the library?
by rpdom
Thu Jul 19, 2018 7:04 am
Forum: General discussion
Topic: How can i use my own domain on Raspberry Pi to serve a website?
Replies: 4
Views: 139

Re: How can i use my own domain on Raspberry Pi to serve a website?

Unless you host your own nameservers, you leave those fields alone. The provider should have another page for adding an IP address A or AAAA record to your domain name.
by rpdom
Wed Jul 18, 2018 6:43 pm
Forum: General discussion
Topic: Relay Module KY-019 5V
Replies: 196
Views: 8767

Re: Relay Module KY-019 5V

I have recently bought some 220VAC 15W LED lamps. They use transformers (I guess from 220VAC to 12/24DAC) and say they are flicker free. Unlikely, almost always capacitive-dropper circuits nowadays. BigClive on Youtube does some interesting tear-downs of this sort of thing and reverse engineers the...
by rpdom
Tue Jul 17, 2018 8:22 pm
Forum: Python
Topic: Light off function problem
Replies: 1
Views: 89

Re: Light off function problem

Looks like a simple typo in the code

Code: Select all

        var lightOff = function() {
            document.getElementById('myImage').src='/static/pic_bulboff.gif';
            sendCommand('On');
            console.log("Light Off");
        };
Shouldn't that be sendCommand('Off'); ?
by rpdom
Tue Jul 17, 2018 6:21 pm
Forum: General discussion
Topic: How to automatically run a program in Raspberry Pi?
Replies: 15
Views: 347

Re: How to automatically run a program in Raspberry Pi?

Actually, my server.c is C++ program but I can use "g++ server.c -o server -lwiringPi" to compile it. After that, I got a server exe file. That would be a "server" executable file. Not an "exe" which is a windows thing. So, your file should be called server and the line to run it should be ExecStar...
by rpdom
Tue Jul 17, 2018 5:23 am
Forum: General discussion
Topic: Using Hard Drive with Raspberry Pi
Replies: 45
Views: 9397

Re: Using Hard Drive with Raspberry Pi

I tried taking the board out of the enclosure/300GB hard drive and put it on a 7200RPM hard drive that is supposed to have 320GB of data on it. On the sticker, it says it has 5VDC and 0.65A, then it says 12VDC 0.50A right under that. I'm guessing that means 5 volts, 0.65A direct current or 12 volts...
by rpdom
Mon Jul 16, 2018 8:07 pm
Forum: Troubleshooting
Topic: Pi 3B+ / Shorting 3.3V to GND
Replies: 14
Views: 310

Re: Pi 3B+ / Shorting 3.3V to GND

The chip doesn't need to melt, just a small amount of damage will be enough.
by rpdom
Mon Jul 16, 2018 4:46 am
Forum: Java
Topic: a quick performance comparison of java on raspbian
Replies: 39
Views: 31993

Re: a quick performance comparison of java on raspbian

They are the output from the "time" command shown by -rst-, which measures resources used by your code. You can put "time" in front of any command line to see what it uses. "real" is the actual time the process took to run. "user" is the amount of cpu time used for your user process. "sys" is the am...
by rpdom
Sun Jul 15, 2018 3:35 pm
Forum: Troubleshooting
Topic: File attachments
Replies: 6
Views: 109

Re: File attachments

Zip the file and attach that. Zip files are allowed.
by rpdom
Sun Jul 15, 2018 8:01 am
Forum: Troubleshooting
Topic: Raspberry pi 3 b+ won't boot with multiple SD cards
Replies: 7
Views: 149

Re: Raspberry pi 3 b+ won't boot with multiple SD cards

As you are using a 3B+, can you try putting one of the SD cards into a USB adaptor, plugging that in to the Pi (with no card in the usual slot) and see if that boots. If it does, it means that the SD card slot has been broken in some way, but you can still boot from USB. If it doesn't, it possibly m...
by rpdom
Sun Jul 15, 2018 7:56 am
Forum: Teaching and learning resources
Topic: Seeking help on curriculum design for kids
Replies: 11
Views: 370

Re: Seeking help on curriculum design for kids

Thank you for the Code Club site! The projects are so well designed and structured. We have been seeking curriculum for young girls especially at elementary school age (a high percentage of girl scouts are under 13). Code Club's projects are for 9-13, which are great resources. Four of our last lot...
by rpdom
Sun Jul 15, 2018 7:13 am
Forum: Networking and servers
Topic: Best choice of web server on Raspberry Pi
Replies: 5
Views: 264

Re: Best choice of web server on Raspberry Pi

I don't know where you get the idea that Apache is insecure.

I use Apache and nginx web servers.
by rpdom
Sun Jul 15, 2018 6:46 am
Forum: Teaching and learning resources
Topic: Seeking help on curriculum design for kids
Replies: 11
Views: 370

Re: Seeking help on curriculum design for kids

There's also the Code Club projects (now run by the RPF). All Code Clubs must register, but anyone is able to access and use the course material available. There are projects for Scratch, Python and HTML/CSS, along with some for the micro:bit, Sonic Pi and the Raspberry Pi and Sense Hat (with online...
by rpdom
Sat Jul 14, 2018 8:02 pm
Forum: General programming discussion
Topic: Question About Compiling RasPi Apps
Replies: 9
Views: 340

Re: Question About Compiling RasPi Apps

Build on a Pi 3B and move it to the Zeroes once complete.
by rpdom
Sat Jul 14, 2018 5:15 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: ADC for analog video (possible?)
Replies: 26
Views: 689

Re: ADC for analog video (possible?)

It does both. If you use raspivid to record a video it uses H264 hardware encoder to compress it. Sure, but that isn't going to be real-time, is it? The accelerator hardware can provide real-time decoding. Easily. I've use the omxtx program to hardware decode mpeg2 video and encode to H264 (mp4) at...
by rpdom
Sat Jul 14, 2018 7:04 am
Forum: Beginners
Topic: Connect USB device via GPIO pins?
Replies: 4
Views: 155

Re: Connect USB device via GPIO pins?

If you are really keen, and good at soldering/desoldering, you could remove one of the USB connector pairs and wire the device in to the holes.

You could break your Pi if you get it wrong.

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