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.

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2answers
490 views

Arduino stops sending/receiving data over Serialport after random time

I got a C# WPF application wich communcates with my arduino uno over serial port. Everything works fine for 3 to 20 seconds then i can not send or receive anything from/to the arduino. What im trying ...
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1answer
582 views

Can't use uint16_t in library

I wonder why the following minimal example sketch doesn't compile (unknown type name 'uint16_t'): sketch_does_not_compile.ino: #include "myheader.h" void setup() { char a[]="hello world"; ...
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2answers
128 views

Mixed structure with int and string

I want to create a structure like this: struct commands { int cmd; char descr[25]; }; commands cmds[] = { {16, "Hammond Organ"}, {17, "Percussive Organ"}, {18, "Rock Organ"}, { 0, "" ...
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1answer
194 views

Scope of RtcDateTime object when declared outside of a function

I'm trying to merge 2 Arduino samples, in order to be able to use DS3231 RTC module with ESP8266 WiFi simple web server. My RTC library is this: https://github.com/Makuna/Rtc/wiki Generally, to code ...
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0answers
90 views

ESP8266-01 Serial.print returns a blank given a valid string

I am currently trying to create a led matrix with ws2812b leds. I am using an uno on the rear of the display to control the leds and now I want to add wifi capabilities. Since I already had serial ...
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1answer
241 views

String to Dynamic Byte array

I'm new in Arduino stuck in String to a dynamic byte array. My String: String Finalval="6D616320747820636E662031352033300D0A"; Dynamic Byte array: byte ft[]={0x6D,0x61,0x63,0x20,0x74,0x78,0x20,...
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1answer
79 views

PWM using timer3 for servo control won't generate any output

I'm making a program for a small robot arm controlled by four servos. Problem: I need for PWM outputs, timer1 has three so i need to use timer3 for the last one The main program and the timer1 ...
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0answers
287 views

SPI communication with Arduino and PGA411-Q1 resolver sensor

I have been trying to implement SPI communication between an Arduino board and a PGA411-Q1 resolver sensor board. I have set up the Arduino SPI settings as indicated on the resolver sensor's datasheet ...
2
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1answer
307 views

Publish chipid to mqtt using ESP32-CAM

I have been trying to push the data of temp, humidity, and pressure from a sensor to MQTT using ESP 32Cam, and was able to do using the following code: pressure = bme.readPressure(); //Convert the ...
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1answer
36 views

Is if statement correct?

if(temperature < baselineTemp)else{ digitalWrite(2, LOW); digitalWrite(3, LOW); digitalWrite(4, LOW); }else if(temperature >= baselineTemp+2 && temperature < baselineTemp+4){ ...
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1answer
164 views

Laser Controller using Arduino Uno

---> I am trying to create a controller using Arduino Uno that simply detects pulses from a waveform generator mimicking a Laser Machine and then switches between 4 state machines states at the output ...
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1answer
173 views

Code conversion

Following is the zabbix documentation with the query header format. Document Zabbix I have difficulty implementing this header in C ++ (Arduino), I saw an implementation of what I need in this forum ...
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1answer
111 views

Receiving i2c bytes on an attiny85

I've been trying to write a small i2c lib in C over the past week. I managed to get writing to slaves working (for example I can write to an ssd1306 oled) but reading (for example date/time from an ...
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0answers
41 views

Where is tcp.c?

This question is related to my other question, which I already answered. I want to add modify tcp.c to include my own code. The problem is I can't find tcp.c. The first thing I tried was looking in ...
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3answers
819 views

How can I connect 6 solenoid locks to an arduino

Im in college and our research is about a fingerprint based door lock system. We really dont have any idea about arduino. Now we bought arduino mega for our research but I dont know how to connect ...
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3answers
15k views

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 ...
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0answers
52 views

about required memory size in ATmega32 to execute a certain program

If I want to add two numbers and print the output on LCD char answer[8]; float a=5.1,b=3.2,c; c=a+b; dtostrf(c,8,3,answer);//convert float to ASCII to print it on LCD for(i=0;i<8;i++) ...
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0answers
292 views

Arduino error in code Stack smashing protect failure!

I get the error when I compiled my code below. I am making an application to read temperature on board ttgo esp32 oled lora stack smashing protect failure! abort() was called at PC 0x400da3e8 on ...
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1answer
461 views

Can't Compile .ino using ArduinoJson Library

I am using an ESP32 NodeMCU for which I wrote working software before. This also occurs when I just try to compile without uploading, so no hardware problem. I am using the newest version of ...
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0answers
68 views

Problem in fetching http get request after put float number

I have this codes that works correctly! #include <DFRobot_sim808.h> #include <SoftwareSerial.h> #define PIN_TX 7 #define PIN_RX 8 SoftwareSerial mySerial(PIN_TX,PIN_RX); ...
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1answer
121 views

How can I stop a loop when using a servo with a Key input?

How can I stop my following code using a key? Basically the code should run the servo in a loop if "t" is pressed and stop the loop if "s" is pressed. #include <Servo.h> Servo myservo; // ...
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1answer
41 views

arithmetic operation outcome differs from the expected outcome

I am writing a function void Sound_Play(int frequency,int millisec) A part of this function is: counting=(millisec*frequency/1000); //counting is type int Serial.println((String)"millisec="+...
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0answers
328 views

ESP32 OTAWebUpdater only works on mobile

I'm experiencing something strange. I opened the default ESP32 example "OTAWebUpdater" in the ArduinoIDE and modified just the network part (I created a soft AP instead). The problem is, when I ...
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1answer
226 views

Serial communication PC to Arduino using C and send via NRF

I'm trying to communicate my PC with an Arduino Mega via serial and after send the message via NRF to another Arduino. But I don't know if the message is send correctly or if it even send the message....
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2answers
305 views

How do I implement reverse enumeration?

Basically I'm trying to output a string based upon a value in an array, the following code is what I have come up with to achieve my desired result, but I have a feeling that there is a better way to ...
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1answer
134 views

Serial communication between PC and Arduino using C

I'm trying to send some data to my arduino mega 2560 using serial communication. I'm using the exemple that I found here without success. Every site I read say that I can send data to the arduino ...
2
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3answers
1k views

Variable declaration inside main loop

In the past I declared variables inside the main loop which worked just fine. In a new project I did the same: void loop(void) { uint8_t counter; .... if (buttonPress) counter = 0;...
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1answer
739 views

Rounding float number

I want to enable user to change the duration of PWM from 0 to 255, the number should be in minute and increase/decrease with two push buttons. (X) x 255 / 60000 = minute In above example each time ...
2
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1answer
770 views

Arduino wrap or subclass print() to work with multiple Serial

I am writing an Arduino program that uses Bluetooth on Serial1 to print text to a Bluetooth terninal on an Android phone and also normal Serial to print text to the serial monitor on a laptop. I would ...
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0answers
216 views

How to control motor in trapezoidal manner using arduino

I am Working on a project in that i have to control motor in a Trapezoidal motion profile. on Y-axis is the velocity and X- axis as a time. Velocity increases linearly for a certain time, then ...
1
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1answer
185 views

Problems with Serial.read()

void loop() { if (sensor.begin() == true) { Serial.print("Current Conversion Mode: "); Serial.println(sensor.getConversionMode()); Serial.println("Enter your mode of Conversion (number ...
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2answers
138 views

strtoul behavior between C and Arduino

I have this code C code that compiles OK on my laptop #include <stdlib.h> #include <stdio.h> #include <string.h> unsigned int crc32(const void *m, size_t len) { const unsigned ...
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1answer
725 views

Running Python on Arduino

I've been using Python for quite long, and I was wondering if it can be used as a programming language for Arduino, rather than C/C++. When I'm using the Arduino IDE, the sketch is compiled into a ...
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1answer
615 views

"variable does not name a type

Hey guys I'm getting an error that is im pretty sure to do with how i am initializing my variables. It is: exit status 1 'threshold' does not name a type Here's my code: //Global Variables for ...
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2answers
305 views

Multiple defintion error, Linker error [closed]

Trying to create an elf file for two sets of files in different folders. LIDARBOT.h ----------- #ifndef LIDARBOT_H_ #define LIDARBOT_H_ #include <avr/io.h> #include "drivers/motors.h" #endif ...
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1answer
58 views

Split serial monitor output to only save part of the output

This is the output i get from the serial monitor from using a HM10 in . How could i go about splitting the data using arduino uno. I only want to save the last 12 digits before the :- (4CAA0DE091B7) ...
2
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0answers
189 views

local libraries and include dependencies

I'm using PlatformIO in Atom for Arduino programming. I get dependencies error when build. This is my reproduction sample code: /lib/mylib/mylib.h #ifndef MYLIB_H #define MYLIB_H #include <...
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0answers
207 views

Arduino Sensor Values to Raspberry Pi using NRF24

Im trying to send temperature sensor data through NRF24L01 to Raspberry Pi and read it in Raspberry Pi using python. But the temperature sensor data comes to the Raspberry Pi as letters, which I found ...
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1answer
2k views

Stack smashing protect failure ESP32 with Modbus RTU

I'm doing a project using an ESP32 TTGO with LoRa, the Max485 and a WELLPRO ADAM 8082 for Modbus communication. I'm trying to use the ESP32 as a master to and the ADAM as a slave. I'm also using Node-...
1
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0answers
439 views

UDP Packet not receiving

I started a project where I wanted to send sensor data from one arduino to another and let this 2nd Arduino send the data to a tablet to visualize sensordata like speed, temperature etc. I wanted to ...
1
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1answer
290 views

Display not showing output - Arduino Wattmeter

I have been playing with this code for some time now, I am able to show the results in an 16X2 LCD display, but I am not able to do it in an OLED. here is the code #include <SPI.h> #...
1
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1answer
453 views

Working with Wire core library

I'm studying the Wire library code driver utility/twi.h to learn how twi buffering and ISR management work. What I did actually, is that I copied the header/source files from the Arduino path F:\...
4
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3answers
5k views

Using an external header file

I have a project that is part of a larger repository, and shares header files with non-Arduino C programs. I know that it's possible to use these headers by copying them to the libraries folder, or ...
3
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5answers
9k views

How to compare a string

How to compare a string coming from serial monitor with some predefined text stored as a local variable? If I say: int led = 2; String a = " abcds"; void setup(){ Serial.begin(9600); } void loop(...
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1answer
2k views

Pass structure pointer as an argument to a function in c

I am developing a code in which I need to pass a structure pointer value to a function as a parameter. I am calling function "proto485Compare()" in "RS485TaskSlave()". "rs485Msg" contains my data for ...
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1answer
126 views

Question on pin management using PCA9534PW IO Extender

There is an IO expander PCA9534PW, Arduino UNO. I don’t really understand how I can manage this expander using UNO over I2C. I found an example, but here is the reading mode. What I need: Set the ...
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1answer
193 views

Using two leds with one push button [closed]

How can I make the code of this project where I will press one time a button, to turn on the first led (and turn off second led) and when other one press to turn on second led (and turn off the first ...
0
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1answer
64 views

When does a pre/post increment occur? [closed]

Editing here to clarify. The headline asks the question but the example given was not ideal. This was a more general Q than about the example code. Compilers have sequence points, places where you ...
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1answer
5k views

Length of uint8_t* const array

I've an array of type uint8_t* const with 6 items, defined like this uint8_t* const neighbourSet[] = {PEER1, PEER2, PEER3, PEER4, PEER5, PEER6}; Whereas each element in this array is static uint8_t ...
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1answer
5k views

'RtcDateTime' does not name a type

I've tested a code that compiles successfully. But after i merged it to another code, here it shown an error says RtcDateTime doesn't name a type. Used library : https://github.com/Makuna/Rtc Some ...

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