Questions tagged [c]
C is a procedural programming language which is widely used in embedded systems. PLEASE NOTE: Arduino is typically programmed in C++, not C.
431 questions
0
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1
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Serialise a struct containing a flexible array
I want to serialise and deserialise a struct containing a flexible array.
I did find a working code but wondering if it is the most elegant and optimum way to do it.
This is my first attempt below ...
- 163
0
votes
2
answers
83
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I need help with code with two IR sensors using ATMega16
I'm working on a ball-counting project using two IR sensors to detect balls entering and exiting a room, but I'm currently stuck. I need help refining the logic in my while loop. Here's how I want it ...
- 11
12
votes
6
answers
5k
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Using String instead of C string, yet another attempt to touch a loaded issue
I've been reading a lot over the years why we should not use the notorious String class and how heap fragmentation is bad practice and not professional and we should never use it in our programs or we'...
- 411
0
votes
1
answer
122
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Problem with char* variable malloc/free. Empty contents on recipient variable after using free
I am working on a custom SD card data logger using the following function and struct:
char *filenameCreator(const char *prefix, const char *num, bool addExtension)
{
char *filename = (char *)...
- 111
2
votes
2
answers
6k
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How to use Interrupt in Arduino to receive the data from Serial Input
Currently i have a project that forced me to make a program that receives several data from Serial Input using Interrupt in Arduino. I use Arduino as the receiver and ESP32 as the sender through ...
- 21
-1
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1
answer
363
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Declaration of global variables in separate file: compiler conflict
So I have:
1/ My myapp.ino file, that includes src.h (implemented in src.cpp). Compiled for Arduino Uno.
2/ I also have a unit-tests.cpp file that is meant to test functions in src.cpp. Compiled for ...
- 99
4
votes
1
answer
697
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Problem with reading data from ELM327
The idea was to create a bluetooth device on the arduino to read data from the machine (ELM327 v2.1) using the HC-05 bluetooth module.
In this code the bluetooth module is switched to MASTER mode and ...
- 141
-1
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1
answer
561
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SPI with DMA in a Arduino Due
I have a project where I need to store data (~16 Mo) on a memory and be able to fetch the data fast (<36000 bits/s) with DMA because I have other signals to take care of.
Currently I use an SD card ...
- 49
0
votes
1
answer
95
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Serial com register formula
i am working on a atmega328p, learning to uses its registers instead a coding with common arduino code.
i've found this formula to get the baud rate on the Serial port (using USART protocol) :
how ...
- 3
1
vote
2
answers
510
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Working with pulseIn() and millis()
I'm trying to use pulseIn with elapsed time using millis(), I don't want to use interrupts instead of pulseIn (I need pulseIn because I need accurate pulse time), the elapsed time doesn't need to be ...
- 89
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4
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1k
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How to send multiple bytes with Wire without copying
When I need to send multiple bytes via Wire, for example a long int, I cast it to a byte array and specify a length
long int i;
Wire.write((byte*)&i, 4);
But if I want to send bytes from more ...
- 33
4
votes
5
answers
18k
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How to convert byte *payload to String
I would like to convert a byte *payload to a String, because I want to compare the content of payload to another String.
void mqttCallbackHandler(char *topic, byte *payload, unsigned int length) {
...
- 175
16
votes
6
answers
21k
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Arduino: How to get the board type in code
I want to write a sketch that can be compiled on different Arduino boards.
I want to display on the PC which board is currently connected.
This means that the user connects the PC via USB cable to ...
- 481
7
votes
3
answers
52k
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How do I extract code from an arduino? [duplicate]
I updated and uploaded some code on another computer that got wiped and didn't send the new code to my current computer, the updated code is still on the board but I don't have access to it. How do I ...
9
votes
2
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8k
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Arduino interruption (on pin change)
I use the interrupt function to fill an array with values received from digitalRead().
void setup() {
Serial.begin(115200);
attachInterrupt(0, test_func, CHANGE);
}
void test_func() {
if (...
- 91