embedded

问题 I am working with time-critical applications where the microsecond counts. I am interested to a more convenient way to develop my applications using a non bare-metal approach (some kind of framework or base foundation common to all my projects). A considered real-time operating system such as RTX, Xenomai, Micrium or VXWorks are not really real-time under my terms (or under the terms of electronic engineers). So I prefer to talk about soft-real-time and hard-real-time applications. An hard

问题 here i want to encrypt and decrypt files using AES 256 Algorithm than i have to provide Key for Encrypt the files and same key for decrypt the files. So which Key is better for good performance and Security also? Which type of Format of key i will use here so i can get more security. Here i have to use same key in Encrypt and Decrypt. So Any body please can suggest me the better suggestions for Key. 回答1: An AES key is just a bunch of bits with no structure. An AES-128 key is 128 bits, which

问题 In terms of embedded development using C code, I understand that when a program is compiled and linked, a binary or ELF file is produced which executes on the target. The ELF file will contain (along with alot of other stuff ) the addresses or address offsets of global variables. Now, when the C startup code executes first, it can copy non-const data / variables from flash memory into RAM if this data is to be modified throughout the program. This will then change the memory addresses of the

问题 I am using STM32f4 discovery board connected with xbee to receive temperature data from remote temperature sensor. Code used is CMIS UART example code. I will receive packet data, 1 byte at a time. In other words UART receive interrupt will be called whenever each byte receives. Once I gets the complete packet I will copy the temperature data. My UART callback function works without any issue. But after several hours, UART receive interrupt stops working and UART cannot receive anything.

问题 I am working on rasberry pi board. Is it possible to directly access the GPIO physical address from linux kernel space using inb(), outb()... ?. If yes how ?. GPIO register address link Page 90 http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf Thank you 回答1: Yes. Get a virtual address mapping setup to the registers in question using ioremap Use readl/writel to manipulate the physical memory. Beware that ARM processors will fault on unaligned accesses. Linux

问题 I would like to be able to debug how much total memory is being used by C program in a limited resource environment of 256 KB memory (currently I am testing in an emulator program). I have the ability to print debug statements to a screen, but what method should I use to calculate how much my C program is using (including globals, local variables [from perspective of my main function loop], the program code itself etc..)? A secondary aspect would be to display the location/ranges of specific

问题 I would like to be able to debug how much total memory is being used by C program in a limited resource environment of 256 KB memory (currently I am testing in an emulator program). I have the ability to print debug statements to a screen, but what method should I use to calculate how much my C program is using (including globals, local variables [from perspective of my main function loop], the program code itself etc..)? A secondary aspect would be to display the location/ranges of specific

问题 I wanted to ask, how will behave DMA SPI rx in STM32 in following situation. I have a specified (for example) 96 Bytes array called A which is intended to store the data received from the SPI. I turn on my circular SPI DMA which operates on each Byte, is configured to 96 Byte. Is it possible, when DMA will fill my 96 Bytes array, the Transfer Complete interrupt will went off, to quickly copy the 96 Byte array to another - B, before circular DMA will start writing to A(and destroy the data

问题 I wanted to ask, how will behave DMA SPI rx in STM32 in following situation. I have a specified (for example) 96 Bytes array called A which is intended to store the data received from the SPI. I turn on my circular SPI DMA which operates on each Byte, is configured to 96 Byte. Is it possible, when DMA will fill my 96 Bytes array, the Transfer Complete interrupt will went off, to quickly copy the 96 Byte array to another - B, before circular DMA will start writing to A(and destroy the data

问题 I see an issue where I can correctly draw a textured polygon if all vertices remain onscreen within a perspective projection, BUT if I scale the quad large enough such that one more more vertices fall 'too far behind' the viewing volume, then the resulting OpenGL drawing is incorrect (see screenshots). The texture mapping becomes skewed, and it appears as though the offscreen vertex 'moved' and becomes distorted. I am using GLES 2.0 code on a GLES 3.0 compliant driver (details at bottom). I