embedded

Is it safe to build with -fsigned-char with Android NDK?

由 徘徊边缘 提交于 2019-12-04 11:15:58
问题 For consistency with other platforms, I need to use signed char in some native code I'm working on. But by default on Android NDK char type is unsigned . I have tried to explicitly use signed char type but it generates too many warnings differ in signedness when string constant/library functions are involved, so I'm looking to build my code with -fsigned-char . I'm now trying to anticipate problems regarding Android ARM ABI and API when -fsigned-char is used, but I can't find any problem yet.

Is it worth offloading FFT computation to an embedded GPU?

由 人盡茶涼 提交于 2019-12-04 10:32:20
问题 We are considering porting an application from a dedicated digital signal processing chip to run on generic x86 hardware. The application does a lot of Fourier transforms, and from brief research, it appears that FFTs are fairly well suited to computation on a GPU rather than a CPU. For example, this page has some benchmarks with a Core 2 Quad and a GF 8800 GTX that show a 10-fold decrease in calculation time when using the GPU: http://www.cv.nrao.edu/~pdemores/gpu/ However, in our product,

RS232 (UART) on STM32F4-Discovery (STM32F429ZIT6) with HAL library?

由 不问归期 提交于 2019-12-04 10:10:28
Background Here is some of my background so that your guy could know what related knowledge I have or I don't have. I'm totally a newbie of this kind of embedded system. And I don't really know anything about electronics, I'm a pure software guy. My only experience of embedded system is Raspberry Pi, which is quite different from STM32F4 Discovery. I could implement a UART read / write programming by using standard Linux C library on Raspberry Pi, which is connected to a PC with an USB-to-RS232 adapter with a voltage converter IC. My Device and development environment An STM32F429I-DISCO board

What is an embedded system? Can Mobile be considered as an embedded product?

由 血红的双手。 提交于 2019-12-04 08:50:25
问题 What is mean by embedded system? If a system/machine or product which we are making is for multiple purposes, then can we consider it as an embedded system? Or is it that only a system dedicated for a particular task that is considered as an embedded system? Can a PC/mobile/laptop be considered as an embedded system or not? 回答1: Generally an embedded system is one placed into operation for a specific, narrow purpose, and lacking the kind of general purpose user interfaces you would find on an

Recommendations for embedded+realtime development training [closed]

由 拈花ヽ惹草 提交于 2019-12-04 08:46:04
问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 3 years ago . I am currently studying for a career in embedded real time engineering. But find it somewhat difficult to find good training material. Especially because you cannot experience embedded development as you would with desktop application development. Are there any books and or kits that would be useful for basic

Seeing how Instructions get Translated (Computer Architecture)

由 倾然丶 夕夏残阳落幕 提交于 2019-12-04 07:53:54
问题 Little bit of a confusing question. But Im really looking for learning some low level programming. Thing is, Dev boards like Arduino/Etc. really hide alot of whats going on. I have spent some time learning about Computer Architecture, Logic/Gates/Sequential Logic/etc.. (I went even as far as to learn the Physics of Semiconductors and Electronics related to it all, just to know what exactly is going on, as well as how Gates are made using CMOS Transistors and such). But thats about where it

Write on a mtd block device

由 眉间皱痕 提交于 2019-12-04 07:53:44
问题 I'm trying to write on a NAND flash memory using MTD block device but I don't understand everything. As I read here mtdblockN is the read only block device N mtdN is the read/write char device N mtdNro is the read only char device N But I'd like to directly write bytes to the partition using a simple write in C and I don't understand how it works (I read somewhre that I first must erase the sectors I want to write on). Which device should I use and how to write on this device? 回答1: Reading

What is the bootloader and startup code in embedded systems? [closed]

由 你。 提交于 2019-12-04 07:41:04
问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 6 years ago . What is the basic significance of bootloader and startup code in the embedded systems? What is the difference? Where are these placed?? And an overview of the flow from power on reset to the application start.

Quickly find whether a value is present in a C array?

由 ￡可爱￡侵袭症＋ 提交于 2019-12-04 07:38:47
问题 I have an embedded application with a time-critical ISR that needs to iterate through an array of size 256 (preferably 1024, but 256 is the minimum) and check if a value matches the arrays contents. A bool will be set to true is this is the case. The microcontroller is an NXP LPC4357, ARM Cortex M4 core, and the compiler is GCC. I already have combined optimisation level 2 (3 is slower) and placing the function in RAM instead of flash. I also use pointer arithmetic and a for loop, which does

ARM cortex: mutex using bit banding

由 爷，独闯天下 提交于 2019-12-04 07:35:22
Given that, on the ARM Cortex M3, I can: atomically read a single bit atomically set a single bit atomically clear a single bit How can I combine these for a mutex style set of operations: try lock take lock release lock It seems that try_lock or take_lock would require two operations that would not be atomic. Do I need more control to accomplish this? Disable global interrupts would do it but it seems there should be a more surgical approach. Your rwl_TryLock() doesn't necessarily return a failure if the lock is already held when it's called (your compiler should be giving at least a warning
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