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Closed 9 years ago.
I have been investigating the use of the PJSIP SIP stack on a small micro-controller such as the PIC32 MCU and I've come to realise that it may just be possible. I want only the absolute minimal SIP functionality so I just might be able to fit PJSIP on a small MCU. Of course, it's a VERY ambitious project but I'm gonna give it a try anyway. I just can't seem to wrap my mind around the right operating system for use so I'm gonna spend a good couple weeks on this subject. I'm gonna take a look at FreeRTOS. Any thoughts on the compatibility of FreeRTOS with something like PJSIP?
I think the project site itself answers your question:
On portability
On Size
The memory resources suggested would be at the upper end for most on-chip memory. The RTOS's listed are all significantly more fully featured than FreeRTOS which provides little more than thread scheduling, timer services, synchronisation and IPC. You'd need to understand what OS services it assumes. Presumably it uses the platform's network stack? FreeRTOS has no network stack - you'd have to provide that too - more resources again.
Related
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Closed 9 years ago.
Whats the best way to do an application where an phone is the server and the others phones are the clients. The clients will do requests to the server and the server will respond..Requests maybe to the server sends the real time audio that they are capturing..Whats the best way to do this in ios? Using UDP Multicast? Or an TCP Socket per client?
Using UDP multicast will cast your messages to all devices in your network (hence the name). It also does not guarantee delivery and it does not garauntee delivery order (FOFI) either. In most situations, UDP isn't really a good idea.
TCP is a really great alternative, it's easy to use, and it does garuantee all those things and there are many frameworks or C libraries out there that can help you a lot.
Personally, I'ld recommend using libuv and attaching the uv runloop to NSRunloop, but you can use AsyncSocket too, if you'ld rather like to stick to Objective-C.
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Closed 10 years ago.
How do I get started writing an operating system that runs on the arm architecture? I want to write a bootloader if possible and my own kernel. Can anyone help me get started?
I'd start by familiarising yourself with what is already out there - Linux is a good start. Look at the bootloaders used in the distributions on the rPi - what is used in Debian Squeeze for example, uBoot and BareBox. Another option is CFE - which is under BSD license and good during debugging/early development.
Another thing is to look at the ucLinux and ucLibC systems, along with buildroot and OpenWRT - all designed to squeeze it onto a small system.
Of course - building your own kernel - you are going to want to go far deeper - and spend time understanding MMU's, process management/multitasking, interrupts and so on. A good background in programming microcontrollers, a knowledge of assembler language and CPU/SOC architecture would be essential. With the ARM family - you'll want to know the various instruction sets supported, and which chips have features like MMU's, FPU's and similar.
Good luck - it sounds like an interesting project.
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Closed 10 years ago.
If I am using CLLocationManger with kCLLocationAccuracyThreeKilometers for getting Coordinates and never stop it.
Have you any idea that in how much time my iPhone battery will drain?
This question is difficult to answer as there are many variables involved, such as, device model, device age, OS version, GPS chipset (varies among device models), ... This is one of the reasons why you should strive to optimize your usage of the GPS functionality.
Apple, for example, caches location data on regular time intervals so it can provide third party applications with location data (1) fast and (2) without the need to fire up the onboard GPS, which requires time and power. (For your information, cached location data is of course not an option if your application relies heavily on location services).
In short, don't count the battery for your application to function properly. Instead, make clever use of the location services.
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Closed 11 years ago.
Can I write an operating system using machine language directly?
Please give me a general idea or sources as to how to do it.
First, study the x86 or ARM instruction sets. Then, study up on operating systems. You'll see why it's not a great idea: it's like filling a sandbox one grain at a time with tweezers.
Yes, all you need is a lot of patience, sanity, and a binary editor.
After awhile you will realize why assemblers were created, which is the lowest level I would generally bother going to.
** yes you can but this is very diffecult for any one
and if you do this what make programmers and all design programming lanaguages to make things
easily comparing by machine code
and this is project as you ask
it's an OS written in machine code it's still under developing
http://www.magicschoolbook.com/computing/os-project
note : your name is like my name iam glad to answer you
best wishes**
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Closed 11 years ago.
I have seen Operating Systems described as "the software that controls the hardware". I don't understand what it really is however.
For example, if we are writing code for a calculator, if we write the code to implement the interface between the LCD and KEYPAD, that code is not considered an operating system is it?
what really does "Operating System" mean?
Jack, the wikipedia page on operating systems gives a pretty good overview to start with. To put it pretty simply, when you want to run multiple pieces of software on a single piece of hardware (in your case, the ARM chip) then something needs to control the access to the hardware. The operating system will schedule tasks and allocate hardware to allow the multiple different bits of software to co-exist peacfully. Without this control, there is no way to run multiple pieces of software at once. Your calculator example would not require an operating system, as it is a single piece of code to do a single job.
For compilers for the ARM devices, I would suggest looking at either GCC (which I believe can cross compile to ARM) or getting a development kit, which will likely come with a suite of tools to allow you to develop on it.
I'm afraid I can't help you on which version of ARM chips to choose though, as my experience with them is a little limited. If price of the hardware is an issue though, I believe the ARM 7 hardware will be cheaper, but it is always worth comparing.
Hope this helps.