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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.

2
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1answer
62 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 ...
0
votes
0answers
12 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 ...
0
votes
1answer
42 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 ...
0
votes
2answers
41 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 ...
1
vote
1answer
79 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 ...
0
votes
1answer
29 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 ...
1
vote
2answers
31 views

Multiple defintion error, Linker error

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 ...
0
votes
1answer
27 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) ...
1
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0answers
38 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 <...
0
votes
0answers
11 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 ...
0
votes
1answer
43 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-...
0
votes
0answers
17 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 ...
0
votes
1answer
25 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
vote
1answer
55 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:\...
3
votes
2answers
170 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 ...
0
votes
0answers
34 views

PWM C Code some logical error

I don't know what's wrong with the code I have activated all the bits I need. I want the code to slowly increase the brightness of the bulb and then reset and then the same thing goes on. Please help ...
2
votes
4answers
159 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(...
0
votes
1answer
30 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 ...
0
votes
1answer
32 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 ...
-2
votes
1answer
43 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
votes
1answer
47 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 ...
1
vote
1answer
296 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 ...
0
votes
1answer
549 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 ...
0
votes
1answer
73 views

Random number/sequence output

The program I'm trying to build is: Type in 1st name, hit enter, type in 2nd name and then hit enter again. Register those names from string input to char naming in student struct. Print out the ...
0
votes
1answer
44 views

What's going wrong with my EEPROM?

I've been chipping away at a project for a long time now and I've found a serious bug. Basically the user has an 8x8 grid, and each cell in this grid has a number of properties. I want to be able ...
1
vote
3answers
86 views

How to assign text stored in a local file to a string at compile time

I'm developing a program that uses the HTML server in the WiFi101 library. My hardware does not have SD card storage so all source html needs to be stored as strings in the sketch at compile time. ...
0
votes
1answer
95 views

Read Serial data from an arduino with c code

I am trying to receive data through the serial port from my SBC (a TS-7200), i am working with linux and handle serial communication using C/C++.To send data to the SBC i'am using an arduino uno. So ...
0
votes
1answer
23 views

Can you save data to heap section in Arduino memory?

On normal computers, heap will be cleaned as you close the program, but can I save data to Arduino's heap with malloc function. And will it be cleaned after I power off the Arduino?
0
votes
1answer
56 views

C: No communication to a connected serial port?

I'm trying to connect to an arduino Mega At2560 unit connected via usb serial port in my linux based PC. Using C code, I'm trying to send and receive simple text strings, just I'm able to send and ...
0
votes
1answer
101 views

How to handle concurrent HTTP request when using interrupt

I'm trying to make a door sensor with a reed switch. Each time the there is a change, the ESP8266 sends an HTTP request to web service. Unfortunately, the ESP8266 serial monitor dumps a huge stack ...
0
votes
0answers
59 views

append a String on ArduinoJson Object value

I've a json string request coming from server and I convert it into json object StaticJsonBuffer<500> jsonStaticBuffer; JsonObject& root = jsonStaticBuffer.parseObject(String(msg)); ...
0
votes
0answers
81 views

Double precision floating point operations using Arduino

Today we were programming something in university which dealt with really large numbers (even larger than unsigned long) and we had to create a code that broke the numbers into an array and performed ...
0
votes
3answers
173 views

Creating a library for arduino

I found a really nice 24 bit I2C adc which was fairly cheap as well (ADS1219) but as far as I could tell there are no libraries for it so I decided to make my own. I have managed to write functions ...
1
vote
0answers
27 views

Low Level programming - MKR Fox1200

I'm working on a project using this board and wish to do so on a low level ,as in enabling certain registers to enable interrupts etc. I can't seem to find the correct header files to support ...
1
vote
3answers
511 views

Why to store a function parameter value in a class private variable?

I'm just curious, I'm going through a C++ library for the mcu2.4 TFT display. And this method I notice when I run through C++ libraries. Which is when a parameter is passed through a function, it's ...
1
vote
0answers
74 views

Why does the program size increase so drastically with these switch-cases?

EDIT: The problem is my op-code catch is op >= 0x20 || op <= 0x2F rather than op >= 0x20 && op <= 0x2F and so most of the switch-case was being optimised away! This is a really ...
0
votes
1answer
39 views

Optocoupler on Tinkercad acting weird

So, maybe it's my understanding that is at fault or maybe it's tinkercad. It's probably the former. But anyway here's my problem I've connected it according to picture https://imgur.com/a/h2HYgUE ...
0
votes
1answer
190 views

How can I concatenate these two values as a string?

I've tried all the supposed solutions for the exact error, pasted into google, that I could find on every forum including this one and no matter the alleged solution I will either get the error about ...
0
votes
2answers
42 views

Button state changes despite not being connected?

I have written some code to test buttons that I want to use const int buttonPin1 = 1; const int buttonPin2 = 2; const int buttonPin3 = 3; const int buttonPin4 = 4; const int buttonPin5 = 5; const ...
0
votes
1answer
58 views

Value assignment on Arduino

I have a thermocouple k. I want this thermocouple to select the first value OF TEMPERATURE that it read and assign it to a variable in an Arduino program. How should I do that?
0
votes
1answer
216 views

Read Multiple Sensors Data from a text file located in SD Card in Arduino/ESP32

I am working on a small home project 'glucose meter' via non invasive techniques. I am using four sensors like RGB color sensor, two multi-wavelength photo diodes (A & B) and temperature sensor (K-...
1
vote
3answers
610 views

Code for a rolling average

Below is some code I wrote to find the rolling average of a temp sensor hooked up to an arduino and display it to an lcd display. My issue is that for the first minute it is running, the average is ...
0
votes
1answer
54 views

Formula creation

I was creating a scoring formula for a game. The formula in question is millis() * 1.1 ^ (millis()/10000); However, I'm having trouble understanding the different error messages that the Arduino ...
1
vote
1answer
571 views

How do I directly access a memory mapped register of AVR with C

Assume I want to write the following without using DDRD or PORTD: #include <avr/io.h> #include <util/delay.h> int main(void) { DDRD = 0xFF; PORTD = 0xFF; } I found this link ...
1
vote
1answer
196 views

How is it possible to access the CPU registers using memory addresses?

The following is taken from ATmega328-328P Data sheet. According to this, I can access all the 32 registers in CPU using memory addresses. For example: unsigned char *register = 0x0; will access ...
1
vote
1answer
46 views

How is a long int stored in an 8 bit Arduino register

Assume the following code in C: long int a = 262143; which in binary will be 111111111111111111 (18 bits). If an atmega328p register can hold 8 bits, how is the above represented in the register? ...
0
votes
1answer
98 views

ESP8266 12-E can't connect to any Access Point with converted variables from strings to char arrays

I'm using an esp8266 12-E nodemcu I wrote a code that scans the available WiFi networks, print them through serial communication,ask the user which network he wants to connect to and then the password ...
1
vote
2answers
72 views

Why is there no embedded c code in arduino libraries?

When I took a look at how the arduino libraries were coded I expected to see register names like I/O registers(PINx,DDRx,PORTx) and other such registers with values assigned to them but instead I saw ...
0
votes
7answers
865 views

How to parse 20180810T143000Z to time_t

What is the shortest/most elegant way (i.e. use existing lib functions) to parse a string in the form of 20180810T143000Z to a time_t? Note that the literal always represents a UTC timestamp. I ...
0
votes
3answers
4k views

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) { ...