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by rpdom
Sun May 20, 2018 3:39 am
Forum: Troubleshooting
Topic: Pi 3 is Destroying SD Cards
Replies: 34
Views: 6686

Re: Pi 3 is Destroying SD Cards

It is very possible that the heat was caused by a fault in the card. The card slot does not normally get hot, maybe a bit warm if anything. A very small number of people have reported cards getting very hot and failing - not just in Pi's, but in all sorts of other devices. Not just microSD cards, fu...
by rpdom
Sat May 19, 2018 6:28 pm
Forum: General discussion
Topic: Upgrade confusion?
Replies: 15
Views: 437

Re: Upgrade confusion?

Just one follow-on question: How does one know that a reboot is necessary to load the upgraded kernel? Is this (should it be) a routine part of the upgrade procedure? That is a very good question. I seem to remember upgrades on older Debian Linux systems used to give a message that a reboot was req...
by rpdom
Sat May 19, 2018 8:42 am
Forum: General discussion
Topic: Problem on MAX30105 sensor on Raspberry Pi 3
Replies: 14
Views: 333

Re: Problem on MAX30105 sensor on Raspberry Pi 3

Hi Lawson and rpdom, Thanks for your reply. It means that if I really supply the 5V to the sensor, the 5V will burn my SDA or SCL pins of raspberry pi? As long as the sensor doesn't have pull-ups to 5V on board (and most don't), you'll be OK. However, from the schematic it appears that board does h...
by rpdom
Sat May 19, 2018 8:05 am
Forum: General discussion
Topic: Problem on MAX30105 sensor on Raspberry Pi 3
Replies: 14
Views: 333

Re: Problem on MAX30105 sensor on Raspberry Pi 3

I have two I2C RTCs and a BMP180 temp sensor all running at 5V. I use 5V for MCP23017s. I haven't fried a RPi yet. So the pull-up on the open drain is 5V safe. That's got nothing to do with it. 5V never appears on the i2c lines, no matter what the other devices are powered at. They are NOT 5V SAFE!...
by rpdom
Sat May 19, 2018 7:29 am
Forum: General discussion
Topic: Problem on MAX30105 sensor on Raspberry Pi 3
Replies: 14
Views: 333

Re: Problem on MAX30105 sensor on Raspberry Pi 3

DougieLawson wrote:
Sat May 19, 2018 7:24 am
Because I2C is open drain.
That doesn't make it "5V safe" at all. Put 5V on it and it dies. If any device on the bus has pull-ups to 5V then you risk frying the GPIO.
by rpdom
Sat May 19, 2018 7:02 am
Forum: General discussion
Topic: Problem on MAX30105 sensor on Raspberry Pi 3
Replies: 14
Views: 333

Re: Problem on MAX30105 sensor on Raspberry Pi 3

DougieLawson wrote:
Sat May 19, 2018 6:47 am
The I2C interface on pin#3 & pin#5 has 1.8KOhm resistors so that it's 5V safe. The secondary interface on pin#27/pin#28 doesn't have that hardware so is NOT 5V safe.
How does a pull-up to 3.3V make the pins "5V safe"?
by rpdom
Sat May 19, 2018 5:50 am
Forum: Troubleshooting
Topic: Can't Get LED to light
Replies: 14
Views: 256

Re: Can't Get LED to light

The circuit looks good and the LED sounds like it is the right way around. If the LED doesn't light even when the connection is made to pin 1 (3.3V) instead of pin 11 (GPIO17), then the LED is dead, the resistor is wrong (that looks like a 390 Ohm to me, but that should work), or one of the wires is...
by rpdom
Sat May 19, 2018 5:16 am
Forum: Troubleshooting
Topic: Can't Get LED to light
Replies: 14
Views: 256

Re: Can't Get LED to light

You can upload small images (up to 64KB) as attachments and place inline with your post. Otherwise upload to an external site like imgur and post a link to the image.

I just noticed I forgot one other possibility: The LED could be the wrong way round. They don't work if connected backwards.
by rpdom
Sat May 19, 2018 4:11 am
Forum: Troubleshooting
Topic: Raspberry pi 3 won't download php5
Replies: 2
Views: 51

Re: Raspberry pi 3 won't download php5

PHP5 is old news. PHP7 is the current version. There are a few differences, but most code will run under 7 with no changes, and faster too. I recently updated a load of my code from php5 to php7 and the only changes I had to make were for the mysql access. The old mysql_* functions aren't available,...
by rpdom
Sat May 19, 2018 3:51 am
Forum: Troubleshooting
Topic: Can't Get LED to light
Replies: 14
Views: 256

Re: Can't Get LED to light

If the LEDs don't work when connected to 3.3V and GND, via the resistor of course, then there are a few possibilities: * The LEDs are dead. * The wiring is wrong. Can you show a picture of your breadboard setup? Some breadboards have a break in the middle of one of the power rails at the side which ...
by rpdom
Sat May 19, 2018 3:48 am
Forum: General discussion
Topic: What is the latest version of tmux I can install without having to compile it?
Replies: 4
Views: 103

Re: What is the latest version of tmux I can install without having to compile it?

It looks there are some arguments in the tmux community about this. https://github.com/tmux/tmux/issues/810

If you build from the source on github it always sets the version to be "master". That should be the latest version or higher, whatever the version number of that is.
by rpdom
Sat May 19, 2018 3:41 am
Forum: Off topic discussion
Topic: Front panel program?
Replies: 12
Views: 335

Re: Front panel program?

I seriously lusted after an Acorn Archimedes at the time. I got an early one (with a decent trade discount), after I'd seen them at the launch party in London, then played with one at Acorn in Cambridge. It was really nice to work with. :-) If I understand correctly the ARM1 only had about 24000 tr...
by rpdom
Sat May 19, 2018 3:30 am
Forum: Troubleshooting
Topic: Can't Get LED to light
Replies: 14
Views: 256

Re: Can't Get LED to light

LTolledo wrote:
Sat May 19, 2018 3:17 am
Have you tried lighting the LED on the breadboard connecting the wire originally for GPIO17 to the +5V? We are taking out the RPi first to check if your breadboard circuit works.
Better to try connecting the wire to +3.3V, as that is what the GPIOs can supply.
by rpdom
Sat May 19, 2018 3:25 am
Forum: Off topic discussion
Topic: Front panel program?
Replies: 12
Views: 335

Re: Front panel program?

the memory management hardware built into the ARM processor. You're making me feel old now :lol: In the first ARM computer (Acorn Archimedes), the memory management was a separate chip to the ARM, as was the IO controller and Video/audio controller. Acorn produced all four chips (called ARM2, MEMC,...
by rpdom
Sat May 19, 2018 3:12 am
Forum: General discussion
Topic: What is the latest version of tmux I can install without having to compile it?
Replies: 4
Views: 103

Re: What is the latest version of tmux I can install without having to compile it?

Raspbian Stretch (stable) has version 2.3-4 Raspbian Buster (testing) has version 2.7-1, but I wouldn't recommend upgrading to Buster yet. Otherwise you could try building from source, or maybe look at Debian's stretch-backports section, which has 2.7-1 that looks like it will install under Stretch ...
by rpdom
Sat May 19, 2018 3:03 am
Forum: General discussion
Topic: Upgrade confusion?
Replies: 15
Views: 437

Re: Upgrade confusion?

What happened here? Why was a reboot required to get the newer/updated kernel release loaded? You can't upgrade the kernel that is currently running the system*. It is loaded at boot time. That would be like trying to change the engine in your car while driving at 70mph. However, when you performed...
by rpdom
Fri May 18, 2018 2:57 pm
Forum: General discussion
Topic: omxplayer download & install
Replies: 16
Views: 134743

Re: omxplayer download & install

ToryGW wrote:
Fri May 18, 2018 2:51 pm
When I follow that link, it takes me to a Raspbian version called 'STRETCH", not "WHEEZY"
That's what comes of reading a five year old post. When that was posted, Wheezy was the current version of Raspbian. Now it has been replaced by Stretch.
by rpdom
Fri May 18, 2018 5:35 am
Forum: General discussion
Topic: How to install tmux?
Replies: 4
Views: 127

Re: How to install tmux?

The problem was that a recent apt-get upgrade changed the package indexes, so you needed to run apt-get update again after that upgrade to rebuild them, otherwise no software appeared to be available. Generally it isn't required, but it is generally worth doing an update before starting to install s...
by rpdom
Fri May 18, 2018 5:00 am
Forum: Other languages
Topic: moving mysql database to a usb drive
Replies: 14
Views: 403

Re: moving mysql database to a usb drive

pi9 wrote:
Fri May 18, 2018 1:03 am
I tried different variations for the mount command, but I couldn't figure it out.

Code: Select all

sudo mount -t vfat -o uid=mysql /dev/sda1 /mnt/usb
by rpdom
Thu May 17, 2018 7:47 pm
Forum: Beginners
Topic: Where to buy SD cards from?
Replies: 17
Views: 403

Re: Where to buy SD cards from?

It varies. I get some from supermarkets and some from places like https://www.7dayshop.com which have various brands at reasonable prices if you're prepared to wait a few days for them.
by rpdom
Thu May 17, 2018 6:15 am
Forum: Troubleshooting
Topic: Unable to update Rpi in China, DNS issue?
Replies: 9
Views: 185

Re: Unable to update Rpi in China, DNS issue?

It's definitely a DNS issue then, whether because it is being blocked, or for some other reason.
by rpdom
Thu May 17, 2018 5:37 am
Forum: Troubleshooting
Topic: Unable to update Rpi in China, DNS issue?
Replies: 9
Views: 185

Re: Unable to update Rpi in China, DNS issue?

Does "ping 8.8.8.8" work? If not, I suspect Google's DNS is being blocked too. Try one of the other DNS services, like OpenDNS and see if that works, otherwise try and route DNS via your VPN and your local system.
by rpdom
Thu May 17, 2018 5:11 am
Forum: Troubleshooting
Topic: Ethernet LED questions - what is normal?
Replies: 3
Views: 103

Re: Ethernet LED questions - what is normal?

On my 3B+ connected to a 1000Mb switch, I get the orange light on most of the time and it blinks off when there is network activity. I think the green one comes on instead when connected to 100Mb. I'm happy to be corrected on that.
by rpdom
Mon May 14, 2018 3:02 pm
Forum: Beginners
Topic: USB Booting Question
Replies: 6
Views: 167

Re: USB Booting Question

I never got this to work reliably on a 3B with a WD Foundation Edition Pi drive. Maybe 1 time out of 10. Are things fundamentally different on a 3B+? I ended up having to use a small SD card just to get reliable booting. Yes, the 3B+ has some improvements in the boot ROM that support more devices. ...
by rpdom
Mon May 14, 2018 8:25 am
Forum: Beginners
Topic: USB Booting Question
Replies: 6
Views: 167

Re: USB Booting Question

With the 3B+ you shouldn't need the SD card at all. There will be a few seconds delay while the Pi checks to see if there is a valid SD card, before moving on to boot from the USB device.

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