How to choose your Linux Embedded Software Provider

July 23rd, 2015 by pteodorescu in Embedded, Linux

In order to master embedded software, a developer must posses a specific set of technical skills and know-how. The computer engineers who work in the realm of embedded systems, which by definition do not take the form of a traditional computer, design, develop and test specific and sometimes critical functions performed by the device. No easy task since these functions will decide whether a robot on another planet moves as it is supposed to or if a live saving call can be made.

Still wondering about the robot – Linux connection? Well, embedded Linux software can be found in nearly every device around us: in cars as Infotainment systems, in phones as Android and… finally, not so close to us, in the Mars Rover, “Curiosity”. Read the rest of this entry »


For your garden

July 10th, 2013 by Ioan Cocan in Android, Embedded, iOS, Linux, Mobile

RainMachine - The Forecast Sprinkler

In the past few months we’ve helped the guys at RainMachine.com to release a brand new intelligent sprinkler.

For those living in the US, this cool device will take weather forecasts from National Oceanic and Atmospheric Administration and will use them to calculate the perfect amount of water that your garden needs today. You can select smart programs and water your garden selectively on weekdays, even/odd days, or let the sprinkler automatically protect the pipes against freezing temperatures.

If there is no data available, don’t worry! The RainMachine sprinkler will automatically switch to historical weather statistics. This way the device saves water even if the Internet goes down.

You can control your sprinkler from its touch screen. If it’s in a hard to reach place, you can also connect to your sprinkler using your smartphone or tablet and remotely control everything.

The technologies we’ve used: iOS apps, Android apps, Android NDK, HTML5, JavaScript, Sencha, Backbone.js, lighttpd, sqlite, UPnP, and C/C++ Linux programming.

Go get your Sprinkler on Amazon now!


Getting updated Bluetooth discovery names from nearby devices

November 24th, 2008 by lstroie in Linux

I’ve needed to see updated information related to nearby Bluetooth devices.

When using < hcitool scan > command, the output is not updated on every run, and even when used with the –flush option, the obtained results did not reflect the reality because the data is cached.

Do you need cheap dedicated server?

The solution seems to be < hcitool scan –flush –info > . This forces a detailed inquiry that is not cached.

One minor disadvantage would be the bigger amount unuseful data obtained, if we are looking only for the Bluetooth discovery name.


Where in the /dev is the card reader?

November 3rd, 2008 by Bogdan Nitulescu in Linux

I’ve plugged a card reader in a USB socket on my Linux box and it’s not that trivial to know if it’s on /dev/sda or /dev/sdb or elsewhere. That can be even dangerous – I know someone who just erased his hard drive, trying to reformat a card. (Yes, he used a script that assumed the card reader is /dev/sda… and it worked so well on his old machine).

Here’s a method to find it out.

$ cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: ASUS     Model: DVD-E616A        Rev: 1.08
Type:   CD-ROM                           ANSI  SCSI revision: 05
Host: scsi2 Channel: 00 Id: 00 Lun: 00
Vendor: ATA      Model: WDC WD2500KS-00M Rev: 02.0
Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi4 Channel: 00 Id: 00 Lun: 00
Vendor: GENERIC  Model: USB Storage-CFC  Rev: I19B
Type:   Direct-Access                    ANSI  SCSI revision: 00
Host: scsi4 Channel: 00 Id: 00 Lun: 01
Vendor: GENERIC  Model: USB Storage-MSC  Rev: I19B
Type:   Direct-Access                    ANSI  SCSI revision: 00
Host: scsi4 Channel: 00 Id: 00 Lun: 02
Vendor: GENERIC  Model: USB Storage-SMC  Rev: I19B
Type:   Direct-Access                    ANSI  SCSI revision: 00
Host: scsi4 Channel: 00 Id: 00 Lun: 03
Vendor: GENERIC  Model: USB Storage-SDC  Rev: I19B
Type:   Direct-Access                    ANSI  SCSI revision: 00

So here they are – the DVD-ROM, the hard drive, and readers for various types of cards. I’m interested in the SD card reader, so that would be the device identified by “scsi4 Channel: 00 Id: 00 Lun: 03” – that’s 4:0:0:3 .
The second piece of magic

$ ls -l /sys/bus/scsi/drivers/sd/4:0:0:3/block*
lrwxrwxrwx 1 root root 0 2008-11-03 15:03 /sys/bus/scsi/drivers/sd/4:0:0:3/block:sde -&gt; ../../../../../../../../../block/sde

So the SD card I’ve just plugged is in /dev/sde .


Escaping in Bash: how to handle multiple file names containing spaces

October 6th, 2008 by Bogdan Nitulescu in Linux

Did you ever saved file names in a bash parameter, and everything crashed down when they contain spaces?

The script started simple:

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FILENAMES="log-file-1.txt log-file-2.txt"
cp $FILENAMES logs
rm $FILENAMES

When you have spaces, it becomes a nightmare. You’ll probably add a lot of quotes and try first something like this:

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FILENAMES='"log file 1.txt" "log file 2.txt"'
cp $FILENAME logs
rm $FILENAME

Don’t try it at home, it does not work. Bash applies its dreadfully complex parameter expansion rules and you will end up useless errors about things called “log”, “file” and “1.txt” which cannot be found.

Solution: use arrays:

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FILENAMES=(
"log file 1.txt"
"log file 2.txt"
)
cp "${FILENAMES[@]}" logs
rm "${FILENAMES[@]}"

They work only on bash. Here’s a page about how they work.


Create directories in C using mkdir with proper permissions

October 6th, 2008 by Bogdan Nitulescu in Linux

I just wrote a C application where I had to create a directory and let everyone read and write it.  That should be plain easy:

int result_code = mkdir("/usr/local/logs", S_IRWXU | S_IRWXG | S_IRWXO)

Apparently it’s a bit more complex, and I made a beginner’s error. I did forgot about the UMASK (http://www.tech-faq.com/umask.shtml).

Briefly: When you create a new file or directory, some of its permissions are restricted and cannot be set. Each process has a set of restrictions called the umask, and you must use the umask system call to disable or enable those restrictions. In my case, I set the umask to 0, that is no restrictions, created the directory, then restored the umask to its previous value:

mode_t process_mask = umask(0);
int result_code = mkdir("/usr/local/logs", S_IRWXU | S_IRWXG | S_IRWXO)
umask(process_mask);

The code above is not reentrant and it gets a bit more complex if your program is multithreaded, but you get the idea.


Change your Bluetooth address of your Linux machine

August 10th, 2007 by Bogdan Nitulescu in Bluetooth, General, Linux

Do you have Bluetooth on your computer? Is it a Linux machine? For some weird reason, do you need it to have a different address?

If you answered yes to the above, here’s the magic command:

bccmd -d 0 psset -s 0 bdaddr 0x44 0x00 0x66 0x55 0x33 0x00 0x22 0x11

…and your Bluetooth device address (BDA) becomes 11:22:33:44:55:66. Of course, you will replace the underlined numbers with the actual address that you want to write.

It does not always work. You need bluez-utils 3, and you need a CSR chip in your computer or USB dongle. To find out, type hciconfig hci0 version and the manufacturer should be Cambridge Silicon Radio. Last time I checked, they had~70% market share, so you have a good chance of having one.

If you have more than a single device, use “bccmd -d 1 …” for hci1, and so on.

The option -s 0 stores it into the default memory, which is usually RAM – so the new address may be lost after reboot. Your chip may have various ROM stores – use -s 1 to -s 3. If you want specifically to write your new address in ram, use -s 4. Note that the store with the highest number has priority (e.g. if an address is stored in both RAM and flash, RAM has priority)

For gory details about programming CSR chips, you can get documents from http://www.csrsupport.com/