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.
426
questions
0
votes
1
answer
37
views
SPI with DMA in a Arduino Due
I have a project where I need to store data (~16Mo) on a memory and be able to fetch the data fast (<36000bits/s) with DMA because I have other signals to take care of.
Currently I use a SD card ...
- 51
1
vote
2
answers
103
views
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 ...
- 11
1
vote
2
answers
74
views
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 ...
- 71
3
votes
0
answers
114
views
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 ...
- 131
1
vote
0
answers
64
views
Problem changing the state of the blue LED on an ESP8266
I am trying to change the blue LED on my ESP8266. I can do this (sort of...)
In the setupWifi() function below, there is a loop that is supposed to rapidly blink the LED while wifi is connecting. The ...
- 111
1
vote
0
answers
25
views
How to prevent the application code from getting stuck in forever loop when using SerialFlash library in Arduino-Adafruit framework
I have been working on a project that runs on Adafruit's Bluefruit nRF52 board. I used the SerialFlash library for Arduino provided by Paul Stoffregen: https://github.com/PaulStoffregen/SerialFlash....
2
votes
0
answers
77
views
TFT Screen with Arduino UNO does not display as expected
I have a 3.5" TFT LCD communicating in parallel connected to Arduino UNO.
I expect it draws a white circle on a black background but all it does is to show a white screen.
How to fix this?
main.c
...
- 173
2
votes
1
answer
237
views
How does the compiler/assembler work wrt bootloader?
I realized that on the atmega boards the bootloader is programmed into the chip.
I'm curious, when compiling a sketch how does the compiler/assembler differ from compiling a standard C program for a ...
- 161
0
votes
4
answers
297
views
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
-1
votes
1
answer
154
views
How to write arduino code in a c/c++ script
I'm pretty new to arduino. But I have some knowledge about programming in c/c++. I know that arduino is written in c. But it can't be used as normal c/c++ code.
for example ,
instead of including some ...
0
votes
2
answers
65
views
ESP8266 Wemos D1 min pro - how to change TCP_SND_BUF?
Is there any way to change the TCP send buffer size (TCP_SND_BUF) on this module ?
Now it is equal to TCP_SND_BUF = 2 * TCP_MSS = 2 * 1460 = 2920.
Editing lwipopts.h doesn't make any difference.
The ...
-1
votes
1
answer
69
views
Can't get input from 4x4 keyboard
I'd like to make some basic calculator. Currently, I'm struggling with inputs. I wanted to get from user some numerical input, then, I'd like to have an information, which type of calculation he is ...
2
votes
1
answer
2k
views
lcd.createChar() only allows for 8 custom characters
I have a teensy4.1, with a 16 by 2 LCD screen, and an I2C LCD interface.
I was trying to write a bunch of custom characters to an LCD screen, to flip some text.
my issue is that it works fine, but on ...
- 882
2
votes
1
answer
270
views
How to process 20-bit sensor data
I have an acceleration sensor (ADXL355) that returns 20-bit data in three bytes, formatted as 2s complement :
acc3 (bits 19-12) in byte register 3 (mapped to bits 7-0)
acc2 (bits 11-4) in byte ...
4
votes
1
answer
956
views
How arduino PORTB pins are addressed if I want to access them with pointer?
So Let say I want to access Digital Pin 13. Thats port B pin. Is there an memory address associated with this pin 13 of Arduino Uno r3?
How Port B pins are addressed with corresponding pin numbers ...
- 145
0
votes
1
answer
40
views
Do I need to use resisters and ICes for specific sensors.What if I dont use it,Will it impact my arduino board some how like making it useless &faulty
So I was reading about Simple AutomaticLight Controller using LDR. or with the help of LDRSenso. But I have LM393 Photoresistor (LDR) Sensor I like to know are they same thing or somewhat different. ...
- 145
1
vote
1
answer
126
views
Why use multiple filters output thousands value, use one or two filter can output normal value?
Problem
If the loop runs only one simulated pin and uses a filter, it will output normally (analog 1600~2200, filter 0~500), but creating an array to store multiple filtered simulated pin values will ...
- 45
2
votes
1
answer
2k
views
How to build an arduino project with multiple source files?
I'm building an arduino program on linux, using the following Makefile:
ARDUINO_DIR = /usr/share/arduino
BOARD_TAG = uno
ARDUINO_PORT = /dev/ttyAMA0
ARDUINO_LIBS = Wire
include /usr/share/arduino/...
- 153
1
vote
1
answer
71
views
Morse encoder code not working as expected on Arduino UNO [closed]
I'll start saying that I don't have much experience working with Arduino and programming in C. I have an Elegoo Arduino UNO clone.
Recently I was trying to build a morse encode which converts a text ...
- 63
1
vote
0
answers
197
views
I can get arduino code/board to show voltage using analog input but not python/board
I am trying to simply read a voltage from a battery. I am able to work out how to do this using arduino code on an arduino board. (UNO)
When I try to do the same thing on a board using python the ...
Stu Sutcliffe
1
vote
1
answer
291
views
Should I use C or C++ for a pure code implementation of Arduino?
I have an arduino board (SAMD21 microcontroller) which supports either Arduino or CircuitPython programming. I'd like to program in pure C/C++ instead of Arduino, which seems to be possible without ...
- 11
1
vote
1
answer
1k
views
How to fade LED in a defined time using FastLED
I'm using FastLED library, Arduino Nano and 5 addressable LEDs (WS2812B).
I'd like to create the sequence in the image attached. (all in white color for example)
I know how to turn ON each LED every 0....
- 11
12
votes
6
answers
4k
views
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
2
votes
1
answer
3k
views
Arduino parsing of a string using sscanf
Hello I am new to Arduino and C programming.
I wanted to parse string using sscanf fuction
This is my Program
String hith;
int field1,field2;
float field3;
int F1=0,F2=0;
float F3=0;
int h1,h3;
float ...
- 21
2
votes
2
answers
1k
views
How to write nonblocking code, for polling sensor at 100 Hz
I'm using this piece of code to try to poll an IMU sensor at 100 Hz (for a AHRS sensor fusion library).
void loop(void)
{
// nonblocking code variables
static uint32_t last_ms;
uint32_t ms;
// ...
- 377
-2
votes
1
answer
441
views
Do I use an LED or a pullup resistor for stopping "floating" or "ghosting" for a matrix keypad?
I know this sounds simple, but I have an Arduino Mega 2560 and I am making a matrix keypad for a claw machine. It's a 3*4 matrix keypad. Let's just say, I am making this keypad for the claw machine to ...
- 116
1
vote
0
answers
40
views
1 Button + Potentiometer [duplicate]
Sketch
arduino-uno programming
1 Button and 1 Potentiometer
Sketch: Each time the button is pressed, acquire the value of the potentiometer in a array of 10 positions of these values do the average ...
1
vote
1
answer
112
views
int array passed through function has wrong values only after multiple passes
I have this code:
for(int i = 0; i < its; i++) {
x1 = random(0,4);
y1 = random(0,4);
multiLamp(new int[2] {3,1}, new int[2] {x1,x2}, new int[2] {y1,y2}, wait, 2);
multiLamp(new int[...
- 113
2
votes
1
answer
101
views
Arduino buzzer code sequence not triggering
I have a problem with my arduino buzzer:
the code should be doing the following:
I have a security system where in order to open the door you have to enter a 4 digit code from the remote. If the code ...
1
vote
0
answers
190
views
Having trouble compiling in VsCode when including arduino libraries. (Win10)
I recently switched over to Visual studio code and away from the arduino IDE though I am a novice at both. When using VSC and the neopixel library and sample code(strandtest) containing animations ...
- 11
0
votes
1
answer
645
views
esp32s: error: 'WDT_TIMEOUT' was not declared in this scope
I am trying to initialize the watchdog timer.
I have installed
arduino-esp32-master.zip
I have
#include <esp_task_wdt.h>
set but it is not highlighted red indicating the IDE knows about it.
...
- 201
2
votes
2
answers
4k
views
Difference between char array and unsigned char array [closed]
I have written a small test code for Arduino Uno which is as follows:
unsigned char tes[4];
char testing[4];
void setup() {
Serial.begin(9600);
for (int i = 0; i < 4; i++) {
...
- 305
-1
votes
1
answer
158
views
Efficient workflow/tools for converting color images to hex arrays
I would like to display 65k color animated gifs on my oled. I'm using the adafruit library for https://learn.adafruit.com/096-mini-color-oled
Now I need to convert a significant number of images to ...
- 121
0
votes
3
answers
848
views
Run multiple function with different argument/return structure by one function pointer
Edit:
I tried a simple code in Arduino IDE which should've done in the first place instead in doing it in a desktop compiler. Because the results are different by experiment. In the desktop C compiler,...
- 283
3
votes
2
answers
1k
views
How to upload code without closing puTTY
My question is quite simple: can you, somehow, upload Arduino code without closing puTTY's serial console? I hate having to close the program to open it again for reading the incoming information.
- 33
4
votes
1
answer
394
views
Why does Arduino round off some integers but not others when my desktop PC does not do this?
I am writing (in C) some low level digit manipulation routines that convert int to float and vice versa for Arduino. I came across some puzzling behaviour with Arduino rounding some numbers but not ...
- 303
1
vote
0
answers
91
views
Arduino LCD only display image for few second and turn screen to white
I have a problem with my Arduino and LCD touch screen. I create a few functional button in my Arduino. One of the button is START button. Right now, I want the image is display when I touch START ...
- 11
3
votes
2
answers
792
views
Switch case options get broken after a function call
I'm sorry for the basic question, but I have a switch case where any code placed after a certain function call simply never gets called, and I've spent half a day looking at it, so thank you so much ...
- 71
0
votes
1
answer
2k
views
How to include a file from another (parent) directory
This is my structure
program/
src/
Makefile
main.ino
test.h
...
lib/
i2c.h
In main.ino I include test.h and in test.h I'm trying to include i2c.h but it is just not working, I ...
- 153
-1
votes
1
answer
210
views
Arduino waits until button release to activate
I'm fairly new to arduino, and on my own I'm trying to move a servo to the left and right using 2 buttons. I've got it working for the most part, however when I hold the button down nothing happens, ...
- 57
1
vote
1
answer
423
views
Cannot compile F() macro with R"string"
I am trying to compile the following code:
logger.log_info(F(R"(some text here that may take
multiple lines
and here it is done.)"));
But the compiler exists with the following ...
1
vote
0
answers
35
views
serially parse integer after serially read
I want to write below code but I don't know where I doing wrong, so please help me solve this issue.
Serially read some text like number then I want to serially parse integer value into some variable ...
- 31
1
vote
0
answers
89
views
Send message to multiple number
sim.println("AT+CMGS=\"+91xxxxxxxxxx\"\r");
I don't want to write this. I want to write mobile number on serial monitor in Arduino and on that number, i want to send message. how ...
- 31
0
votes
1
answer
419
views
Arduino + Codeblocks C++
I'm writing the code for my Arduino board using Code::Blocks editor. When I create a new project, there is AVR Project and Arduino Project under Projects category. Which one do I select?
- 103
2
votes
1
answer
9k
views
Need help: Cast from 'char*' to 'uint8_t {aka unsigned char}' loses precision [-fpermissive]
I'm trying to convert the string that I receive from the Websocket to uint8_t that I can copy to the data bytes of CAN protocol frame. I'm using an ESP32 chip and programming it on an Arduino IDE. The ...
1
vote
2
answers
945
views
help explain pulseIn function with arduino and Ultrasonic sensor
dears Engineers.. i got stuck with this issue couldn't understand.. please help with explanations.
first i was upset of my ultrasonic sensor reading deviations, that is i examine my sensor indoor and ...
- 11
5
votes
2
answers
2k
views
Jumping to bootloader from application code in atmega328p
I'm trying to program an Arduino Uno (atmega328p) using only the serial Tx/Rx lines (no DTR, so no automatic reset). This is so I can upload code via WiFi/TCP using an ESP-01.
To achieve this, I need ...
- 63
2
votes
0
answers
130
views
Arduino EPROM dumper with utility program in C
I am writing EPROM dumper with Arduino UNO and utility program in C and I am using Ubuntu 20.04. The Arduino sketch works fine, but I am having few problems with the utility program. The first problem ...
- 21
2
votes
1
answer
4k
views
Which Arduinos support ATOMIC_BLOCK?
Is there a definitive list of which Arduino architectures support the ATOMIC_BLOCK() macro, and a list of #defines for each architecture?
I've tried searching through the Arduino cores on GitHub to ...
- 699
1
vote
1
answer
289
views
How I can send data information without work WiFi to LCD?
Hi everyone I am beginning learn coding and the second language English. I have small project I use Arduino uno , esp8266 , dht11 , lcd I2C and use blynk app in my project I have the code and work ...
- 11