Questions tagged [embedded]
Embedded refers to embedded systems, which involves areas such as microcontroller/DSP firmware programming, real-time systems, electronic interfaces, hardware drivers, serial bus communication etc.
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Compiling an application for use in highly radioactive environments
We are compiling an embedded C++ application that is deployed in a shielded device in an environment bombarded with ionizing radiation. We are using GCC and cross-compiling for ARM. When deployed, our ...
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31
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Unit Testing C Code [closed]
I worked on an embedded system this summer written in straight C. It was an existing project that the company I work for had taken over. I have become quite accustomed to writing unit tests in Java ...
762
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36
answers
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Sorting 1 million 8-decimal-digit numbers with 1 MB of RAM
I have a computer with 1 MB of RAM and no other local storage. I must use it to accept 1 million 8-digit decimal numbers over a TCP connection, sort them, and then send the sorted list out over ...
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How can I unit test Arduino code?
I'd like to be able to unit test my Arduino code. Ideally, I would be able to run any tests without having to upload the code to the Arduino. What tools or libraries can help me with this?
There is ...
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Understanding Linux /proc/pid/maps or /proc/self/maps
I am trying to understand my embedded Linux application's memory use. The /proc/pid/maps utility/file seems to be a good resource for seeing the details. Unfortunately I don't understand all the ...
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How do you implement a class in C? [closed]
Assuming I have to use C (no C++ or object oriented compilers) and I don't have dynamic memory allocation, what are some techniques I can use to implement a class, or a good approximation of a class? ...
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How are everyday machines programmed? [closed]
How are everyday machines (not so much computers and mobile devices as appliances, digital watches, etc) programmed? What kind of code goes into the programming of a Coca-Cola vending machine? How ...
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When is CRC more appropriate to use than MD5/SHA1?
When is it appropriate to use CRC for error detection versus more modern hashing functions such as MD5 or SHA1? Is the former easier to implement on embedded hardware?
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Quickly find whether a value is present in a C array?
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 ...
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votes
9
answers
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Difference between const & const volatile
If we declare a variable as volatile every time the fresh value is updated
If we declare a variable as const then the value of that variable will not be changed
Then const volatile int temp;
What ...
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Is there any reason to use C instead of C++ for embedded development? [closed]
Question
I have two compilers on my hardware C++ and C89
I'm thinking about using C++ with classes but without polymorphism (to avoid vtables).
The main reasons I’d like to use C++ are:
I prefer to ...
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Writing a parser like Flex/Bison that is usable on 8-bit embedded systems
I'm writing a small interpreter for a simple BASIC like language as an exercise on an AVR microcontroller in C using the avr-gcc toolchain.
If I were writing this to run on my Linux box, I could use ...
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84
votes
12
answers
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Embedded C++ : to use STL or not?
I have always been an embedded software engineer, but usually at Layer 3 or 2 of the OSI stack. I am not really a hardware guy. I have generally always done telecoms products, usually hand/cell-phones,...
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Why is C++ template use not recommended in a space/radiated environment?
By reading this question, I understood, for instance, why dynamic allocation or exceptions are not recommended in environments where radiation is high, like in space or in a nuclear power plant.
...
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What are the available interactive languages that run in tiny memory? [closed]
I am looking for general purpose programming languages that
have an interactive (live coding) prompt
work in 32 KB of RAM by itself or 8 KB when the compiler is hosted on a separate machine
run on a ...
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11
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What does this GCC error "... relocation truncated to fit..." mean?
I am programming the host side of a host-accelerator system. The host runs on the PC under Ubuntu Linux and communicates with the embedded hardware via a USB connection. The communication is performed ...
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What is a jump table?
Can someone explain the mechanics of a jump table and why is would be needed in embedded systems?
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68
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Simple serial point-to-point communication protocol
I need a simple communication protocol between two devices (a PC and a microcontroller). The PC must send some commands and parameters to the micro. The micro must transmit an array of bytes (data ...
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10
answers
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Unit Testing Embedded Software [closed]
What best practices have you used in unit testing embedded software that are peculiar to embedded systems?
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1
answer
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What is the difference between RTOS and Embedded Linux? [closed]
RTOS and Embedded Linux are used for embedded systems programming. Is Embedded Linux itself an RTOS ? Can anyone list the comparison or difference please?
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Will printf still have a cost even if I redirect output to /dev/null?
We have a daemon that contains a lot of print messages. Since we are working on an embedded device with a weak CPU and other constraint hardware, we want to minimize any kinds of costs (IO, CPU, etc..)...
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Alternatives to Lua as an embedded language?
I am working on an embedded system running Linux on a DSP. Now we want to make some parts of it scriptable and we are looking for a nice embeddable scripting language. These scripts should integrate ...
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How much footprint does C++ exception handling add
This issue is important especially for embedded development. Exception handling adds some footprint to generated binary output. On the other hand, without exceptions the errors need to be handled some ...
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Using Haskell for sizable real-time systems: how (if?)?
I've been curious to understand if it is possible to apply the power of Haskell to embedded realtime world, and in googling have found the Atom package. I'd assume that in the complex case the code ...
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7
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Floating point linear interpolation
To do a linear interpolation between two variables a and b given a fraction f, I'm currently using this code:
float lerp(float a, float b, float f)
{
return (a * (1.0 - f)) + (b * f);
}
I think ...
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57
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7
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How to determine maximum stack usage in embedded system with gcc?
I'm writing the startup code for an embedded system -- the code that loads the initial stack pointer before jumping to the main() function -- and I need to tell it how many bytes of stack my ...
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7
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What is the difference between C and embedded C?
Can any body tell me the differences between them?
srujan
54
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12
answers
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How does an assembly instruction turn into voltage changes on the CPU?
I've been working in C and CPython for the past 3 - 5 years. Consider that my base of knowledge here.
If I were to use an assembly instruction such as MOV AL, 61h to a processor that supported it, ...
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7
answers
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Embedded C++ : to use exceptions or not?
I realize this may be subjective, so will ask a concrete question, but first, background:
I have always been an embedded software engineer, but usually at Layer 3 or 2 of the OSI stack. I am not ...
53
votes
10
answers
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Optimizing member variable order in C++
I was reading a blog post by a game coder for Introversion and he is busily trying to squeeze every CPU tick he can out of the code. One trick he mentions off-hand is to
"re-order the member ...
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How to determine maximum stack usage?
What methods are available for determining the optimum stack size for embedded/memory constrained system? If it's too big then memory is wasted that could be used elsewhere. However, if it is too ...
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Static allocation of opaque data types
Very often malloc() is absolutely not allowed when programming for embedded systems. Most of the time I'm pretty able to deal with this, but one thing irritates me: it keeps me from using so called '...
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14
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Looking for an efficient integer square root algorithm for ARM Thumb2
I am looking for a fast, integer only algorithm to find the square root (integer part thereof) of an unsigned integer.
The code must have excellent performance on ARM Thumb 2 processors. It could be ...
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How can I make my own microcontroller?
How can I make my own microcontroller? I've done some work using GAL chips and programmed a chip to do simple commands such as add, load, move, xor, and output, but I'd like to do something more like ...
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46
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Direct Memory Access in Linux
I'm trying to access physical memory directly for an embedded Linux project, but I'm not sure how I can best designate memory for my use.
If I boot my device regularly, and access /dev/mem, I can ...
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1
answer
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Hosting multiple clients with freemodbus
I am working on a project involving a microcontroller communicating to a PC via Modbus over TCP. My platform is an STM32F4 chip, programming in C with no RTOS. I looked around and found LwIP and ...
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14
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Polling or Interrupt based method
When should one use polling method and when should one use interrupt based method ?
Are there scenarios in which both can be used ?
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Cool Hardware/Devices that can be programmed in .NET?
I'd love to start writting managed code for external devices and sensors. Are there any devices that come to mind that can be coded against using .NET? Any suggestions?
Edit: The main thing I'm ...
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Are Exceptions still undesirable in Realtime environment?
A couple of years ago I was taught, that in real-time applications such as Embedded Systems or (Non-Linux-)Kernel-development C++-Exceptions are undesirable. (Maybe that lesson was from before gcc-2....
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16
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Optimizing for space instead of speed in C++
When you say "optimization", people tend to think "speed". But what about embedded systems where speed isn't all that critical, but memory is a major constraint? What are some guidelines, techniques, ...
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10
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Device misdetected as serial mouse
I'm working on a device which communicates with a PC through a (virtual) serial port. The problem is that the data we are sending occasionally gets incorrectly identified by Windows as a bus mouse, ...
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votes
21
answers
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Embedded systems worst practices?
What would you consider "worst practices" to follow when developing an embedded system?
Some of my ideas of what not to do are:
Avoid abstracting the hardware layer, instead spreading hardware ...
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votes
9
answers
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How do you design a serial command protocol for an embedded system? [closed]
I have an embedded system I'm communicating with over serial. The command structure right now is designed to be operated interactively: it displays a prompt, accepts a few commands, and displays ...
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C++, can I statically initialize a std::map at compile time?
If I code this
std::map<int, char> example = {
(1, 'a'),
(2, 'b'),
(3, 'c')
...
42
votes
4
answers
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How to run a C program with no OS on the Raspberry Pi?
I'd like to experiment using the Raspberry Pi for some different low level embedded applications. The only problem is that, unlike the AVR and PIC microcontroller boards available, Raspberry Pi ...
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17
answers
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Power Efficient Software Coding
In a typical handheld/portable embedded system device Battery life is a major concern in design of H/W, S/W and the features the device can support. From the Software programming perspective, one is ...
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C/C++ HTTP Client Library for Embedded Projects [closed]
So I have trawled through pages and pages of search results on StackOverflow and Google and I have come across very few C/C++ HTTP client libraries suitable for a resource-constrained, embedded ...
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17
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Anyone using Python for embedded projects? [closed]
My company is using Python for a relatively simple embedded project. Is anyone else out there using Python on embedded platforms? Overall it's working well for us, quick to develop apps, quick to ...
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9
answers
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Algorithm to rotate an image 90 degrees in place? (No extra memory)
In an embedded C app, I have a large image that I'd like to rotate by 90 degrees. Currently I use the well-known simple algorithm to do this. However, this algorithm requires me to make another copy ...
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6
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Lookup table vs switch in C embedded software
In another thread, I was told that a switch may be better than a lookup table in terms of speed and compactness.
So I'd like to understand the differences between this:
Lookup table
static void ...
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