embedded

问题 I'm currently developing on a STM32F302VB and I need to perform a software reset. On all my previous projects (with STM32F427 and STM32F030C8), I've always used the NVIC_SystemReset() function successfully. But for some reason it won't work with this chip. The implementation is in CMSIS core_cm4.h and is as follows: __STATIC_INLINE void NVIC_SystemReset(void) { __DSB(); /* Ensure all outstanding memory accesses included buffered write are completed before reset */ SCB->AIRCR = ((0x5FA << SCB

问题 I want use serial port to communicate with another device txdev, the problem is that txdev is sending data asynchronously and i don't want the read function to block, the good thing is that txdev is sending data with fixed size but i don't know how to use this trick. what i'am doing is the following : fd = open(DEVICE_NAME, O_RDWR | O_NOCTTY); bzero(&termios_p, sizeof(termios_p)); termios_p.c_cflag = CS8|CSTOPB|CLOCAL|CREAD; termios_p.c_iflag = IGNPAR; termios_p.c_oflag = 0; termios_p.c_lflag

问题 I am working on SPI communication.Trying to communicate SST25VF032B(32 MB microchip SPI Flash). When I am reading the Manufacturer Id it shows MF_ID =>4A25BF but originally it is MF_ID =>BF254A. I am getting it simply reverse, means first bite in 3rd and 3rd byte in first. What could be the possible reason for that? My SPI Init function is here: //Enable clock control register CLKCON 18 Bit enables SPI CLKCON |= (0x01 << 18);//0x40000; printk("s3c2440_clkcon=%08ld\n",CLKCON); //Enable GPG2

问题 I am working on SPI communication.Trying to communicate SST25VF032B(32 MB microchip SPI Flash). When I am reading the Manufacturer Id it shows MF_ID =>4A25BF but originally it is MF_ID =>BF254A. I am getting it simply reverse, means first bite in 3rd and 3rd byte in first. What could be the possible reason for that? My SPI Init function is here: //Enable clock control register CLKCON 18 Bit enables SPI CLKCON |= (0x01 << 18);//0x40000; printk("s3c2440_clkcon=%08ld\n",CLKCON); //Enable GPG2

问题 I am working with the Zynq 7 of Xilinx. On the Zynq there is a FPGA, an ARM processor and 512 MiB of DDR RAM. When the board is powered on, the ARM processor starts Ubuntu, which initializes the DDR RAM and claims it as its own. On the FPGA, I am developping another processor and I want to give it a piece of DDR memory. Since I am still developing, I would like to somehow allocate a piece of 64 MiB of continous DDR RAM from linux userspace (the device has a MMU). I would then get the start

问题 Let's say you have a pointer to function whose source you do not have and which is "untrusted" because it might read/write to disallowed memory region. Before it executes each assembly instruction, you want to verify that it doesn't access disallowed memory regions. The OS is (almost) bare-metal i.e. a custom RTOS (so no Linux or QNX). This is for a functionality that needs to be enabled not only during development but during normal runtime. Ideally, it'd run something like this: void (*fptr)

问题 We have a Tcl built in our C/C++ application, I found the place in our code where Tcl_EvalObjv is called if the command was not found. I have to admit that the code is pretty old and not many of our developers know what happens in this module. It looks like this: // ... there is some checking if command is registered etc., it fails and the code goes here: std::vector<Tcl_Obj*> tclArgs = { NULL }; for (int i = 1; i < objc; ++i) tclArgs.push_back(objv[i]); tclArgs.shrink_to_fit(); // ...

问题 I am working with a c++ multi-platform project using visual studio 2010, there is a shared portion of code among all platforms, but there is a big portion that is dedicated to each one, I separate them using #if def, but it turns out that code maintenance become very though and the code is cluttered, in addition to problems like code does not compile with some defines turned on or off. Is there any plugin or tool for visual studio that helps in developing multi-platform projects, for example

问题 I am generating a LUT dividing 0-2PI into 512 fragments and then finding sine of these values and storing them as Q1.31 values. Example: LUT[0] = 0 LUT[1] = sin((1/512) * 2*PI) * (2^31) .. .. LUT[511] = sin((511/512) * 2*PI) * (2^31) My inputs are also values in the Q1.31 format. My question is how do I go about using the LUT i.e. what is the algorithm to find the offset values in the table when I get a random value as an input to figure out the sine value Example: int sample_input = 0.125 *

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 9 months ago . is there any alternative of % operator in embedded c ? there are some other ways of doing it such as using while loops in c++. but is it true that modulo operators slow down microcontroller systems ? 回答1: Whether or not the modulo operator slows down embedded systems depends a