I am working on a program in ARM Assembly and C that runs with no OS. I am basing my code on these examples.
I am looking into using all four cores on my ARM board and didn't know where to start. I have seen explanations of how this works in x86, but I haven't come up with anything for ARM assembly in my search. Where should I start to develop multicore ARM assembly? Could somebody provide a basic example that shows this?
EDIT: I am using an Allwinner H3 CPU and I am already planning to use four different programs. I have seen this. However, after doing some research, I cannot find the mailbox addresses for the cores in the datasheet.
Related
I have been developing code for an older device which has an NXP i.MX28 single core CPU which is ARM-based. The device runs Embedded Linux.
I am now upgrading to a better device which has an NXP i.MX6UL quad core processor, of course ARM-based also, and also running Embedded inux.
Is it normal that the same toolchain which I was using for the for building the code for the i.MX28 will also work for the i.MX6UL, even though the i.MX6UL is more advanced with more cores etc.?
I have built my code now for a test with the same compiler and even run it on a Rasberry Pi which seems to run ok. The Rasberry Pi uses a Broadcom BCM2711 SoC with an ARM Cortex-A72 processor which again is a different CPU.
I therefore must ask, will any ARM toolchain build code and be able to run on any type of ARM device regardless?
CPUs differ by the core architecture (incl. instruction set) and set of peripherals. Difference in the peripherals is solved by drivers and HALs. Difference in core arch is solved by the toolchain.
If the toolchain "knows" new arch it will emit the corresponding assembly code, that will run on the new CPU. So, compilers will not produdce the same assembly, but the same source code will run after rebuild, that's the idea of high-level languages.
Problems emerge when old code contains an inline assembly, or uses some specific DSP instructions or libraries
I am currently learning how to emulate both mips(el) and arm architecture using Qemu. The images which I used for both architecture is by aurel32 from this website, https://people.debian.org/%7Eaurel32/qemu/
I noticed that the mips images does not have initrd while the arm images have initrd. I am unsure why arm requires initrd when running Qemu but mips does not.
Anyone know why this is the case?
Thanks for the help!
There is no inherent reason -- you can build an Arm kernel with enough devices built-in to not need an initrd, and you can build a MIPS kernel that does require an initrd. You'd have to ask Aurelien why the two sets of images he built had different configs (assuming he even remembers 6 years later!), but I suspect it's just that for MIPS he was able to use the stock Debian kernel whereas for Arm he had to compile his own kernel, and so the configuration choices for the two weren't identical.
I am reading a primer text on embedded C programming (it is: Barr & Massa, 2007). For companion hardware board to run examples, they recommend Arcom VIPER-Lite. But I do already have Beaglebone Black (BBB) board and I don't want to buy a new board.
The two boards have same architecture, namely, ARM but BBB uses TI AM3358BZCZ100 processor, clocked at 1GHz, whereas VIPER-Lite uses Intel's PXA255 processor, clocked at 200MHz. The BBB board has more memory and basically more of everything.
My question is, can I follow and execute embedded C code examples given in this book on my BBB board? Does embedded C code depend on processors or architecture or something else? I understand that very specific examples addressing particular peripherals/drivers may not be portable from one platform to next but is entire embedded code like this? I am hope I am making sense.
Intel X-Scale is not the same as Cortex-A8 - ARM architecture has been through a number of versions since then, and Intel implemented some proprietary features too. Moreover ARM licencees are free to implement proprietary peripheral sets and subsets of the core architecture.
In particular for board bring-up the PLL and SDRAM controller will be entirely different between different vendor's devices and even between different generations of device from the same vendor.
If you are running code on an already implemented OS (BeagleBone is delivered with Linux already installed), then you will not need to worry about board bring up and peripheral support; but you will also miss out in learning a great deal about embedded systems (other than perhaps embedded systems that run pre-installed or vendor supplied Linux distros, which is a small subset or all embedded systems).
Beyond board bring up the boards will have entirely different peripheral sets, different on-board devices, and differing I/O at different addresses and with different register sets - no code that directly accesses the I/O is will work. Code accessing devices through a standard Linus device driver interface may well work because an abstraction to a common interface is provided by the OS and board vendor or third party device drivers.
If you are not running the code on Linux - or are implementing low-level device drivers, then the programming environment in terms of memory map, MMU, PLL, I/O control, peripherals, and even instruction set will be different and any code will require adaptation, and you will need to get familiar with the corresponding data sheets or reference manuals and also the ARM technical reference.
So the answer is that it depends largely on where you are starting from; bare-metal or Linux.
There are resources related to "bare-metal" development on BeagleBone Black in particular TI's own bare-metal StarterWare library.
The concept you learn from most good text books can be applied any microprocessor or micro controller at a very high level. But if you want learn embedded system programming using Beagle Bone Black I suggest the following youtube links from Prof Derek Molloy. Prof Molloy does a fantastic job of teaching embedded System programming using BBB. Here are few links for you to get started.
The Beaglebone - Unboxing, Introduction Tutorial and First Example
Beaglebone: C/C++ Programming Introduction for ARM Embedded Linux Development using Eclipse CDT
Beaglebone: GPIO Programming on ARM Embedded Linux
The one problem you might want to be aware is that the video were based on Angstrom Distribution. The current BBB is shipped with Debian Distribution.
Also if you want to learn bare-metal embedded system program you might want check out
Embedded Systems - Shape The World
You might also want to take look at the following link for more material.
Beginning with programming microcontrollers
The xscale although ARM instruction set derived is not ARM in the sense that you want to use it. For some reason the native mode is big endian and normal ARM native mode is little endian. But more important the core processor is not insignificant, but not the bulk if the porting effort, most of not all of the peripherals are expected to differ between those two chips, most of the code would need a re-write unless it is a purely portable C program that runs on any say linux, then arm, xscale, x86 are completely irrelevant to the discussion. I suspect you are not in that situation. Even compiled as a generic command line linux app would still have problems in this situation with the endianness.
Basically you are saying I have two fords and I want to take the wheels off of one and put them on the other, without understanding that one is a ford festiva and the other is lets say an F350 pickup. Just because they have the same looking tiny ford badge on them, doesnt mean that the entirety of their components are identical.
If you are desperate to re-use these binaries, you are better off finding or making a simulator for the prior platform and then you can run that on anything.
I was using PIC micro controller for my projects. Now I would like to move to ARM based Controllers. I would like to start ARM using Linux (using C). But I have no idea how to start using Linux. Which compiler is best, what all things I need to study like a lot of confusions. Can you guys help me on that? My projects usually includes UART, IIC, LCD and such things. I am not using any RTOS. Can you guys help me?
Sorry for my bad English
Once you put a heavyweight OS like Linux on a device, the level of abstraction from the hardware it provides makes it largely irrelevant what the chip is. If you want to learn something about ARM specifically, using Linux is a way of avoiding exactly that!
Morover the jump from PIC to ARM + Linux is huge. Linux does not get out of bed for less that 4Mb or RAM and considerably more non-volatile storage - and that is a bare minimum. ARM chips cover a broad spectrum, with low-end parts not even capable of supporting Linux. To make Linux worthwhile you need an ARM part with MMU support, which excludes a large range of ARM7 and Cortex-M parts.
There are plenty of smaller operating systems for ARM that will allow you to perform efficient (and hard real-time) scheduling and IPC with a very small footprint. They range form simple scheduling kernels such as FreeRTOS to more complete operating systems with standard device support and networking such as eCOS. Even if you use a simple scheduler, there are plenty of libraries available to support networking, filesystems, USB etc.
The answer to your question about compiler is almost certainly GCC - thet is the compiler Linux is built with. You will need a cross-compiler to build the kernel itself, but if you do have an ARM platform with sufficient resource, once you have Linux running on it, your target can host a compiler natively.
If you truly want to use Linux on ARM against all my advice, then the lowest cost, least effort approach to doing so is perhaps to use a Raspberry Pi. It is an ARM11 based board that runs Linux out of the box, is increasingly widely supported, and can be overclocked to 900MHz
You can also try using the Beagle Bone development board. To start with it has few features like UART I2C and others also u can give a try developing the device driver modules for the hardware.
ARM Linux compilers and build toolchains are provided by many vendors. Below are your options which I know of:
1.ARM themselves in form of their product DS-5 ;
2.Codesourcery now acquired by Mentor graphics. See some instructions to obtain & install, codesourcery toolchain for ARM linux here
3.To first start programming using ARM (C , assembly ) I find this Windows-Cygwin version of ARM linux tool chain very helpfull. Here. These are prebuilt executables which work under Cygwin(A Posix shell layer) on Windows.
4.Another option would be to cross compile gcc/g++ toolchain on Linux for ARM target of your choice. Search and web will have information about how it is done. But this could be a slightly mroe involved and long-winding process.
enjoy ARM'ing.
First, you should question yourself if you really need to program assembly language, most modern compilers are hard to beat when it comes to generating optimized code.
Then if you decide you really need it, you can make life easier for your self by using inline assembler, and let the compiler write the glue code for you, as shown in this wikipedia article.
Then the compiler to use: For free compilers there are practically only two choices: either gcc or clang.
There is also a non free toolchain from arm which when i last tried, 5 years ago, produced about 30% faster code than gcc at the time. I have not used it since.
The latest version of this compiler can be found here
You can also write standalone assembler code in .s files, both gcc and clang can compile .s into .o in the same way you would compile a .c or .cpp file.
Compile
If you are using a STM32 based microcontroller you need to get CMSIS and GNU arm-non-eabi-gcc package installed. Then you need to write your own makefile to pass your c codes into arm gcc compiler.
Programming
For the programming step you need to install openocd and configure that for your specific programmer. You can find a full description on how to do that on my blog
http://bijan.binaee.com/index.php/2016/04/14/how-to-program-cortex-m-under-gnulinux-arch/ and in my GitHub repository.
IDE
I'm using vim with CTags but you can use gEdit with the Shortcut plugin if you need a simpler text editor.
I am looking for some information on programming ARM devices, in a particular non-particular way [1]. Assume that I am writing code for an ARM processor that is used a machine similar to a Apple II/Atari "**" XL/Commodore 64/DOS-PC, or even something that runs a multitasking OS like VMS or SUNOs. Assume further that any peripherals/OS specific stuff has already been abstracted into subroutines.Examples of this type of programing might be: a text/curses based game like rogue or moria; a curses based word processor ( or rather something based on a curses like library ) ; or a modem/terminal program.
I'm looking for two things. Materials to help learn ARM programming, though the ARM System Developers Guide may be enough, other resources would be helpful I'm looking in particular for something which explains the software ( and relative hardware ie registers ) differences of various generations of processor.
The other thing I'm looking for is a development environment which inculdes, emulation, a decent macro assembler, and a debugger. Along with any thing else that will help me see what is going on inside my programs.
[1] OK. Sorry I just couldn't resist that particular pun.
You have the choice of using ARM Cortex M or A series. If you are going to develop high end applications such as those which run on smartphones / tablets, then learning about ARM A is your choice. If you are going for an emphasis with hardware/low level stuff such as controllers then you should go for ARM Cortex-M. If you are into real time applications (which I doubt is your case, them use the R series).
Most of these new ARM generations are based on ARMv7 architecture and ISA, so reading the manuals on that could get you started. Most recently, a new ARMv8 architecture and ISA have been announced, it supports 64 bit processing.
Download the reference and technical manuals from ARM site to learn about the HW/peripherals.
I would go with auslen's suggestion of buying a board, you could go with TI's Stellaris Launch pad which has an ARM-M4F processor (supports floating point and SIMD), it sells for 12.99$
http://www.ti.com/ww/en/launchpad/stellaris_head.html?DCMP=stellaris-launchpad&HQS=stellaris-launchpad-b
or you could go with ST's discovery board (based on the same processor as above), but has audio, accelerometer and usb on board. it sells for 14.99$ http://www.st.com/internet/evalboard/product/252419.jsp
or the STM F3 board (10.99$)
http://www.st.com/internet/evalboard/product/254044.jsp
In any case, you need to check the examples which come with the board, without which you could go nowhere easily. The board comes with its own drivers, all is abstracted in a way, so you could get started from there!
As for OS, if your interest is an RTOS, ARM provides the CMSIS RTOS for it's M series processors
http://www.arm.com/products/processors/cortex-m/cortex-microcontroller-software-interface-standard.php
This book offers an introduction to the generations of ARM processors. Then focuses on cortex M3. It covers its ISA with lots of assembly code. It also addresses the built-in peripherals and how to start-up with C.
http://www.amazon.ca/Definitive-Guide-ARM-Cortex-M3/dp/185617963X/ref=sr_1_1?ie=UTF8&qid=1352506616&sr=8-1
good luck
infocenter.arm.com and look at the various ARM ARMs (architectural reference manuals) and TRM's (technical reference manuals) for the various architectures and cores. these manuals are better than most other companies documentation. except for the new 64 bit stuff, the difference from one architecture to the next is somewhat subtle as far as the instruction set goes. the major differences have to do with the peripherals, the mmu is a slow changing thing, the interrupt manager has taken big steps and the fpu has been replaced at least once if not twice wholesale (if you even have an fpu which, having one is the exception not the rule it consumes a huge real estate for such little return).
I am confused with your question. I think it is important to draw the line between learning the architecture/instruction set and learning the operating system calls, these are two separate things. Operating system stuff you rarely need to look beyond the source code (C/C++), and the limited asm is for hand tuned C libraries or boostrap code, and interrupt wrappers. Likewise the architecture, registers, instructions, etc vs the peripherals (the cores from arm generally have very very few peripherals, the bulk are in the vendor specific stuff) which I would separate as a separate learning curve, has little to do with asm and the instruction set so no different than learning a peripheral on any other platform, just some addresses you read and write.
If you are looking for non-operating system bare metal the stm32f0 discovery is $10, I highly recommend it. Looks like ti has a stellaris launchpad for just a little more (waiting for mine to arrive so I cant talk much about them, and shipping is free from ti so the cost is basically the same as the stm32 boards) the stm32f4 discovery is about $20 and I would barely call a microcontroller with all the stuff the cortex-m4 has.
Moving up to linux capable or designed for linux systems there is the raspberry pi, beaglebone and open-rd and on up (pandaboard). Again though you are just writing just another linux C/C++ program so there isnt much excitement there (related to a specific platform, the entertainment is the same for all platforms) and very little arm knowledge required if any. It is very easy to use any of these platforms for bare metal programming giving you race car like performance compared to the ARM based microcontrollers.
I have a thumb simulator which you are probably not interested in. gdb has the armulator which was the cornerstone of the company back in the day. skyeye or something like that has an arm instruction set simulator as does qemu, none of them will give you great visibility other than what gdb can provide. opencores has the amber project an armv2 clone, which you can see the close relationship to the armv4 and newer that you will not find rtl for without a box full of cash. with my arm and chip experience (No I do not work for arm) I do find the amber project worth looking at, but many folks wont know what to do with it and really are not interested in that level of visibility. (it is instruction compatible, a good design, but dont think you are looking at an arm design, no secrets there). you can learn the basic arm architecture from it and then move on to hardware for example...
With the microcontrollers being cortex-m based, you might find the older microcontrollers a better stepping stone to the upper end arm cores. ARM7tdmi based stuff like the sam7s and others from nxp, st, atmel, etc which you can still find at sparkfun and microcontroller pros and other places for arduino like prices.