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by rew
Fri Nov 18, 2016 4:43 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Serial port "noise".
Replies: 3
Views: 500

Re: Serial port "noise".

Scotty101: Thanks! That's it!

I was starting to look for the "Send this string to uart" code in the kernel and compiling my own kernel, but just extracting the uncompressed kernel from the distributed kernel.img is easier.
by rew
Fri Nov 18, 2016 12:05 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Serial port "noise".
Replies: 3
Views: 500

Serial port "noise".

I have "stuff" connected to my UART. It does funny things when it gets sent "random" data. I see "Uncompressing " at 115200baud, then "Linux..." at around 1800kbps and 0.31 seconds later "done...\r\n" (still at 1.8Mbaud). Is there a way to prevent this output? I have: dtoverlay=pi3-disable-bt in boo...
by rew
Sun Jul 10, 2016 2:10 pm
Forum: Troubleshooting
Topic: ttyAMA0 returns EOF.
Replies: 1
Views: 264

ttyAMA0 returns EOF.

I have a "smart meter" connected to my pi (zero). I want to log the data to a mysql database, but until then I want to log the raw output to a file... cat /dev/ttyAMA0 >> thelogfile.log that should do the trick. (besides setting the baud rate). I've configured my pi not to do serial console. There i...
by rew
Sat Mar 26, 2016 6:38 pm
Forum: General discussion
Topic: Interaction setting the font and changing the resolution?
Replies: 0
Views: 158

Interaction setting the font and changing the resolution?

A friend has a pi, that was used with a TV. i.e. a lot of pixels but you tend to sit a long distance away. So I increased the console fontsize. Now she bought a small display. When setting the display mode using "tvservice" , the screen always blanks, and never comes back. Could it be that changing ...
by rew
Sat Mar 26, 2016 6:33 pm
Forum: General discussion
Topic: How reliable is the Raspberry Pi 3
Replies: 19
Views: 4086

Re: How reliable is the Raspberry Pi 3

Using the compute module is IMHO only advised if you really need 'pi compatiblity and price is of no concern.
by rew
Tue Mar 01, 2016 2:10 pm
Forum: Beginners
Topic: PI 3 and Raspbian Wheezy
Replies: 48
Views: 33004

Re: PI 3 and Raspbian Wheezy

you may get away with sudo apt-get update && sudo apt-get dist-upgrade sudo rpi-update sudo reboot So far I can report that this does NOT work. I just get the rainbow square. The green led sends MORSE: - - - - . . . . (dash dash dash dash dot dot dot dot (pause) ) UPDATE: I thought I had upgraded t...
by rew
Tue Dec 15, 2015 5:57 pm
Forum: General discussion
Topic: Adding more RAM - presumably impossible?
Replies: 84
Views: 16709

Re: Adding more RAM - presumably impossible?

It's quite possible that SD cards can claim 40Mbyte per second or even more, but certain restrictions in the interface between the processor and the SD card mean that the pi cannot use the fastest communication method with modern SD cards. With a 32-bit bus and 900 M transfers per second, the DDR on...
by rew
Tue Dec 15, 2015 9:59 am
Forum: Raspbian
Topic: Calling a script when WIFI attaches.
Replies: 2
Views: 368

Re: Calling a script when WIFI attaches.

Thanks Dougie. I thought: let's look in the source where that file (or a pointer to it) gets stored, but as far as I can tell, this command will attach to wpa-supplicant and then wait for the event to happen and execute the script whenever it happens. That would mean I'd have to put it in a startup ...
by rew
Mon Dec 14, 2015 11:35 am
Forum: Raspbian
Topic: Calling a script when WIFI attaches.
Replies: 2
Views: 368

Calling a script when WIFI attaches.

Hi, I've mounted a "zero" on my bike. I want it to connect to my home- and work-wifi when I get there. That works. But I also want to trigger running a script to synchronize things: upload the measurements that it has taken over the trip. Everybody suggests that I use an "post-up" script. This works...
by rew
Mon Dec 14, 2015 11:27 am
Forum: Raspbian
Topic: Lite faster than Full version?
Replies: 4
Views: 1125

Re: Lite faster than Full version?

The main reason for "lite" is that it is meant as "non desktop" so there are less files to download and install. It is a good starting point for a server, the non-lite for when you want to use it as a workstation.
by rew
Tue Jul 07, 2015 10:32 am
Forum: Other projects
Topic: Open source USB DMX-512 with RDM (Enttec USB Pro protocol)
Replies: 12
Views: 4371

Re: Open source USB DMX-512 with RDM (Enttec USB Pro protoco

Hi cyrano, Thanks for the feedback. We've changed to the "new look" because google warned us that our site was "hard-to-use" on mobile devices. We now use a "standard" layout that is supposedly better. According to Google the new version is better (they seem to be rendering the site on tons of virtu...
by rew
Thu May 14, 2015 9:47 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI has more speeds
Replies: 15
Views: 28894

Re: SPI has more speeds

Just FYI: I think the datasheet has a typo. It says: "CDIV has to be a power of two", while it intended to say: "CDIV has to be a multiple of two". This suspicion is strengthened by: "Odd numbers rounded down.". There is also a hardware-explanation for this: The SPI and I2C modules in the BCM2835 (a...
by rew
Mon Jul 21, 2014 8:08 pm
Forum: Automation, sensing and robotics
Topic: MCP4728 Quad DAC Help
Replies: 10
Views: 2869

Re: MCP4728 Quad DAC Help

I2C addresses are 7 bits. The eighth bit in the "addressing byte" specifies read/write. This read/write bit is the lowest bit. Now, some people say that the address is "0xC0" and that to read you need to send "0xC1". They mention the WHOLE byte, not just the top 7 bits representing the address. It a...
by rew
Mon Jul 21, 2014 8:00 pm
Forum: Automation, sensing and robotics
Topic: 433 what?
Replies: 46
Views: 7536

Re: 433 what?

The signal from the transmitter will be 100 times more powerful if the transmitter is at 1m than when it is at 10m. And both have to work. So.... the receiver has an automatic gain control. It will amplify the signals it recieves until it recieves SOMETHING. The led is supposed to flicker all the ti...
by rew
Mon Jul 21, 2014 7:46 pm
Forum: Troubleshooting
Topic: B+ second boot issues
Replies: 10
Views: 1370

Re: B+ second boot issues

That would be a hint that your bootcode.bin is the one listed as "old" above, dated 8 jul. I.e. too old to boot a B+.....
by rew
Mon Jul 21, 2014 7:39 pm
Forum: Troubleshooting
Topic: B+ External Hard Drives
Replies: 10
Views: 14044

Re: B+ External Hard Drives

I now have a "decent" setup that can measure the output capabilties of various powersources. Interesting to measure powersupplies marketed as "2A" and then finding out that they max out at 0.35A (just like most 0.5A supplies...)! Anyway, the best powersupply so far is one advertized as 2A which mana...
by rew
Mon Jul 21, 2014 7:28 pm
Forum: Beginners
Topic: Pi photoframe
Replies: 4
Views: 1299

Re: Pi photoframe

Instead of "*.jpg" use ` find . -name \*.jpg` Now the problem is with the filenames/directories that have spaces in them. So the command becomes: find . -name \*.jpg -exec fbi {} + The problem with this is that the number (actually total size) of the arguments to a command in Linux is limited. So if...
by rew
Mon Jan 27, 2014 11:26 am
Forum: General discussion
Topic: Adding more RAM - presumably impossible?
Replies: 84
Views: 16709

Re: Adding more RAM - presumably impossible?

Ah! That's another possibility. I thought he was talking about I2C SRAM, Most RTC chips still have an SRAM area that can be used to store BIOS settings. Those used to be separate chips, but are now normally integrated in the RTC chip. The fact that they used to be separate is apparent because the RT...
by rew
Mon Jan 27, 2014 9:14 am
Forum: General discussion
Topic: Adding more RAM - presumably impossible?
Replies: 84
Views: 16709

Re: Adding more RAM - presumably impossible?

No, I2C is too slow for "disk" like access. My first PC had a 20Mb harddrive. With the proper programming you could use "interleave zero": there would not be another sector between consecutive sectors. That means you could read a track in just over a full revolution. At 3600 RPM, or 60 rotations per...
by rew
Fri Jan 24, 2014 11:19 am
Forum: General discussion
Topic: Adding more RAM - presumably impossible?
Replies: 84
Views: 16709

Re: Adding more RAM - presumably impossible?

The way I understand things is: For larger-than-X memory POPs an extra address line is necessary. The BCM2835 does not have this extra address line(s). Thus it's impossible to add a larger POP memory. I'm not entirely sure if X is 512Mb or 1Gb. So 2G is definitively not possible, 512Mb /is/ possible...
by rew
Sun Dec 15, 2013 10:00 pm
Forum: Advanced users
Topic: How much power can Rpi throughput to USB?
Replies: 6
Views: 1838

Re: How much power can Rpi throughput to USB?

Just power the USB hub from a 12V -> 5V stepdown regulator. Then connect things up. If you use a sturdy enough cable to the hub, the hub will reverse-power the raspberry pi!


(I'm powering a hub from a 5V 60A powersupply and the 'pi from there...) :-)
by rew
Sun Dec 15, 2013 8:34 pm
Forum: Beginners
Topic: Running RPi for 20 mins on battery
Replies: 4
Views: 963

Re: Running RPi for 20 mins on battery

yeah, those LM2596 converters work. I've had a 'pi running on one of those for about a year now. It's powered from a 12V wall-wart. I would recommend getting a 200+ mAh 20C 2S LIPO battery. That will put out 7.4V nominal, allowing for the inefficiency of the DCDC converter. The raspberry pi will use...
by rew
Sat Oct 26, 2013 6:56 am
Forum: Camera board
Topic: Alternatives or replacements for camera flex cable?
Replies: 137
Views: 93454

Re: Alternatives or replacements for camera flex cable?

A few weeks ago, someone ordered an extension kit with only 20 or 30cm of "cable". We wondered WHY? So I asked. The answer was exactly this: He wanted to put the camera on a pan-tilt, the ribbon cable we provide is much more durable than the FPC. I haven't heard back, so I'm assuming this works........
by rew
Sun Jun 30, 2013 9:20 am
Forum: Add-ons
Topic: Powering the Pi and External 3.5" Hard drive with same PS
Replies: 5
Views: 8826

Re: Powering the Pi and External 3.5" Hard drive with same P

You can also get an LM2596 based DCDC converter. These are much cheaper than the one you found, but requires you to find a way to connect the output to the 'pi instead of a micro USB cable. (e.g. cut the micro USB cable).
by rew
Sun Jun 30, 2013 5:49 am
Forum: Camera board
Topic: CSI Camera, Car and Raspistill . Problems
Replies: 12
Views: 3622

Re: CSI Camera, Car and Raspistill . Problems

Apparently the max listed clock rate is 92 MHz for 1280x720 @60FPS.

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