embedded

Do interrupts interrupt other interrupts on Arduino?

人盡茶涼 提交于 2019-12-03 09:43:27
I have an Arduino Uno (awesome little device!). It has two interrupts; let's call them 0 and 1 . I attach a handler to interrupt 0 and a different one to interrupt 1, using attachInterrupt() : http://www.arduino.cc/en/Reference/AttachInterrupt . Interrupt 0 is triggered and it calls its handler, which does some number crunching. If interrupt 0 's handler is still executing when interrupt 1 is triggered, what will happen? Will interrupt 1 interrupt interrupt 0 , or will interrupt 1 wait until interrupt 0 's handler is done executing? Please note that this question specifically relates to

Library for audio resampling

此生再无相见时 提交于 2019-12-03 09:29:05
问题 In an embedded (Windows CE) C++ project, I have to resample an arbitrary sample-rate down (or up) to 44100 Hz. Is there a free and portable C/C++ library for audio resampling? 回答1: This page lists a bunch of options. Formatted exert, for the records. Please check out the above link for important details and licence information: libresample and sndfile-resample (from libsamplerate ) (in the Planet CCRMA Distribution). libsoxr , the SoX resampler library ssrc (from Shibatch) There is a project

Need some ignition for learning Embedded Systems [closed]

℡╲_俬逩灬. 提交于 2019-12-03 09:09:16
I'm very much interested in building applications for Embedded Devices. I'm in my 3rd year Electrical Engineering and I'm passionate about coding, algorithms, Linux OS, etc. And also by Googling I found out that Linux OS is one of the best OSes for Embedded devices(may be/may not be). I want to work for companies which work on mobile applications. I'm a newbie/naive to this domain & my skills include C/C++ & MySQL. I need help to get started in the domain of Embedded Systems; like how/where to start off, Hardware prerequisites, necessary programming skills, also what kind of Embedded

u-boot : Relocation

北战南征 提交于 2019-12-03 09:08:52
问题 This one is a basic question related to u-boot. Why does the u-boot code relocate itself ? Ok, it makes sense if u-boot is executing from NOR-flash or boot ROM space but if it runs from SDRAM already why does it have to relocate itself once again ? 回答1: This question comes up frequently. Good answers sometimes too. I agree it is handy to load the build to SDRAM during development. That works for me, I do it all the time. I have some special boot code in flash which does not enable MMU/cache.

sources of “uniqueness”/entropy on embedded systems

杀马特。学长 韩版系。学妹 提交于 2019-12-03 09:06:23
问题 I have an embedded system. What I would like for it to do when it powers up or otherwise resets, is to generate a unique ID, so that on different restarts a different unique ID is generated with high probability. It does not have access to a real-time clock, but it does have access to an ADC and a UART. I am wondering if there is a decent way to gather entropy from these sources to generate a unique ID. I am vaguely familiar with Yarrow. Is there a good way to use this? Unfortunately I do not

Debug Linux kernel pre-decompression stage

夙愿已清 提交于 2019-12-03 09:04:22
I am trying to use GDB to debug a Linux kernel zImage before it is decompressed. The kernel is running on an ARM target and I have a JTAG debugger connected to it with a GDB server stub. The target has to load a boot loader. The boot loader reads the kernel image from flash and puts it in RAM at 0x20008000 , then branches to that location. I have started GDB and connected to the remote target, then I use GDB's add-symbol-file command like so: add-symbol-file arch/arm/boot/compressed/vmlinux 0x20008000 -readnow When I set a breakpoint for that address, it does trap at the correct place - right

Acoustic Echo Cancellation (AEC) in embedded software

六月ゝ 毕业季﹏ 提交于 2019-12-03 08:57:24
I am doing a VoIP project on embedded device. I have built a sample using a 32bits MCU with a low grade audio codec. Now I found that there is echo issue on my device, that is I can hear what I said from the speaker. I have do some research and found that most appliaction use a DSP codec with acoustic echo cancellation feature. However, is it possible that I do the acoustic echo cancellation in the software, using my 32bits MCU? Can you adive the algorithm, or even source code:P, for doing acoustic echo cancellation? I know sophisticated method is not possible on a MCU, whereas a simple

Unravelling Assembly Language Spaghetti Code

别等时光非礼了梦想. 提交于 2019-12-03 08:48:23
问题 I've inherited a 10K-line program written in 8051 assembly language that requires some changes. Unfortunately it's written in the finest traditions of spaghetti code. The program--written as a single file--is a maze of CALL and LJMP statements (about 1200 total), with subroutines having multiple entry and/or exit points, if they can be identified as subroutines at all. All variables are global. There are comments; some are correct. There are no existing tests, and no budget for refactoring. A

Lightweight encryption key exchange protocol

送分小仙女□ 提交于 2019-12-03 08:46:07
I have an embedded system posting data to a JSON REST service via HTTP. I'm currently using HMAC-SHA1 for authentication, the same way that Amazon AWS does it. I'm now exploring options for encrypting the data in transit. HTTPS Seems like the logical choice as the server-end would need very little changed. However, my microcontroller has a relatively small flash (256KB) and RAM (96KB) and the only HTTPS clients I can find are commercial products. The microcontroller makes encryption simpler with built in 'AES encryption lookup tables', but I'm guessing I need a secure way to exchange the keys.

ARM TrustZone development

时光总嘲笑我的痴心妄想 提交于 2019-12-03 08:26:32
问题 I am wondering if anyone have any information on development boards where you can utilize ARM TrustZone? I have the BeagleBoard XM which uses TI's OMAP3530 with Cortex-A8 processor that supports trust zone, however TI confirmed that they have disabled the function on the board as it is a general purpose device. Further research got me to the panda board which uses OMAP4430 but there is no response from TI and very little information on the internet. How do you learn how to use trust zone?