embedded

问题 While going through one embedded processor architecture, i have seen the block MMU and it is mainly mentioning about the memory protection functionality. May i know , How an MMU does this protection and why it is needed? What is mean by memory protection? What are the other uses of MMU other than protection(like virtual addressing)? Please consider an embedded system without an OS. __Kanu 回答1: For processors that use memory (most of them) there is a memory interface of some sort, some have

问题 While going through one embedded processor architecture, i have seen the block MMU and it is mainly mentioning about the memory protection functionality. May i know , How an MMU does this protection and why it is needed? What is mean by memory protection? What are the other uses of MMU other than protection(like virtual addressing)? Please consider an embedded system without an OS. __Kanu 回答1: For processors that use memory (most of them) there is a memory interface of some sort, some have

问题 I came across several references to the concept of a dual issue processor (I hope this even makes sense in a sentence). I can't find any explanation of what exactly dual issue is. Google gives me links to micro-controller specification, but the concept isn't explained anywhere. Here's an example of such reference. Am I looking in the wrong place? A brief paragraph on what it is would be very helpful. 回答1: Dual issue means that each clock cycle the processor can move two instructions from one

问题 What features of C++ should be avoided in embedded systems? Please classify the answer by reason such as: memory usage code size speed portability EDIT: Lets' use an ARM7TDMI with 64k ram as a target to control the scope of the answers. 回答1: RTTI and Exception Handling: Increases code-size Decreases performance Can often be replaced by cheaper mechanisms or a better software-design. Templates: be careful with them if code-size is an issue. If your target CPU has no or only a very tiny

问题 I have a legacy firmware application that requires new functionality. The size of the application was already near the limited flash capacity of the device and the few new functions and variables pushed it over the edge. Turning on compiler optimization does the trick, but the customer is wary of doing so because they have caused failures in the past. So, what are some common things to look for when refactoring C code to produce smaller output? 回答1: Use generation functions instead of data

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 6 years ago . I'm trying to familiarize myself with the embedded field, but also have limited resources in terms of time and equipment to buy. What

问题 I am developing an application in VBA. Userforms connect to a COM object that reads an SPSS Statistics SAV file or an SPSS Dimensions MDD file. Part of this application stores metadata in an XML document so that we can retrieve the metadata later and repopulate or update the graphics created from the userforms. This works fine as long as we rely on an XML file existing on a local drive - which is not a desirable solution. We would prefer to embed (not link) the XML in to the PPTM file, which

问题 What I Want : I want to run nodejs on ARMv7 freescale imx6q board with no internet but network connectivity. What I did : I took pre built binary from nodejs official download. extracted them and tried to run node binary. But it throws error "No such file or directory". I have tried changing permissions also. Have a look at logs below. mx6q:/node/node-v5.9.0-linux-armv7l/bin# ls node npm mx6q:/node/node-v5.9.0-linux-armv7l/bin# ./node bash: ./node: No such file or directory mx6q:/node/node-v5

问题 I think I'm thinking about this the wrong way, but I'm wondering how an embedded system with less than 32-bits can use 32-bit data values. I'm a beginner programmer so go easy on me :) 回答1: base 10 0100 <- carry in/out 5432 +1177 ====== 6609 never brought up in class but we can now extend that to two operations 100 32 +77 ====== 09 01 54 +11 ====== 66 and come up with the 6609 result because we understand that it is column based and each column treated separately. base 2 1111 +0011 =====

问题 I think I'm thinking about this the wrong way, but I'm wondering how an embedded system with less than 32-bits can use 32-bit data values. I'm a beginner programmer so go easy on me :) 回答1: base 10 0100 <- carry in/out 5432 +1177 ====== 6609 never brought up in class but we can now extend that to two operations 100 32 +77 ====== 09 01 54 +11 ====== 66 and come up with the 6609 result because we understand that it is column based and each column treated separately. base 2 1111 +0011 =====