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Questions tagged [data-type]

Identifies the size and nature of information held by a variable in a program. It is language-dependent. Examples for C/C++ include: `int`, `float`, and `char`.

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2answers
59 views

SoftwareSerial receives beginning of data mangled

I'm using SoftwareSerial to communicate with a Sigfox module. Documentation for the read function assigns its value to a char. However using it I get mangled characters and also have read in other ...
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1answer
34 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
26 views

Data Structures and Color Data Types in FastLED

So i'm doing something wrong but i don't exactly know what and hope somebody can give me a quick pointer: I declared a starting color for my fastled animation: CHSV startcolor(100, 255, 255); and ...
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1answer
38 views

Unexpected results when creating 32-bit int from byte array

I'm having problems creating a 32-bit integer from a 4-byte array. In the following complete, minimal, and verifiable example, converting a byte array containing 0x00, 0x04, 0x04F, 0x45 results in ...
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1answer
53 views

Change data-type String

I'm currently working with an ESP8266 NodeMCU V3 and an IR transmitter breakout board. The module receives NEC IR commands trough a HTTP request and then sends them trough the IR transmitter. Getting ...
3
votes
1answer
130 views

Print unsigned long long in ESP8266

I need to print an unsigned long long variable: unsigned long long t = 1559072327000ULL; I have tried the following: Serial.println(t); // call of overloaded 'println(uint64_t&)' is ambiguous ...
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2answers
73 views

Problem in defining a variable as multiplication

I have a simplest code to turn on and off a led. The variable holding time definition is onTime, using Arduino Nano. When it is written as: onTime=1000*30, all is good. When onTime is greater than ...
0
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1answer
37 views

Data type conversion problem

I have a Wemos D1 board with a OLED display using the u8g2 library. I am printing my MAC-adress on the serial port & would like to print the same information on the OLED: #include <...
0
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1answer
61 views

invalid conversion from 'uint16_t* error when creating an array of uint16_t items

I'd like to create an array of remote control codes provided by the raw read feature of the irlib2 library. irlib2 provides the following uint16t arrays using the following format: #define ...
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2answers
110 views

What data type are the analog pin labels (A0, A1, etc)?

Arduino Mega I would like to have an array containing analog pin labels something like... int analog_pins[] = {A0, A1, A2, A3}; int num_analog_pins = sizeof(analog_pins) / sizeof(analog_pins[0]); ...
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0answers
67 views

Buffer to string

I'm a bit of a noob, so excuse if this is more obvious to me than to you. I want to convert a u16 to a string. The u16 is the data coming in from the sensor. I need it as a string, or anything else ...
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1answer
96 views

How to parse multi line serial data with an unknown number of lines? [closed]

Here's the example data I've read in H-Term: \r\n \r\n NO:0015\r\n G: 5.97kg\r\n T: 0.00kg\r\n N: 5.97kg\r\n \r\n \r\n How to save the number including "kg" to each variable (NO, G,...
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0answers
141 views

Integer corruption

I use a sensor to measure the temperature. This is returned as float. I feed this float using typecasting (int) to a blink function. This works fine. But the next is step is using this same unchanged ...
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vote
1answer
2k views

Can't create an array of type const char*

I have something being returned as a const char* and would like to save it to an array. I've tried this: const char* book[amtBooks] = ""; and get this error: error: array must be initialized with ...
2
votes
3answers
81 views

Is the strange problem I'm having to do with comparing floats?

I have a timer interrupt that controls a stepper motor, on an UNO board. In the interrupt handler it checks the speed of the motor and compares it to the target speed. This allows the motor to ...
0
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3answers
92 views

How to map 6 bytes of raw data to long long type?

I'm trying to solve some problems for a contest, and I have a problem with it. I have to implement a function that has 3 arguments like this: void foo(unsigned char* A, unsigned char* B, unsigned ...
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1answer
84 views

Casting custom shared_ptr object

I am using custom shared_ptr class for some program on Arduino, and I need to do something like this: shared_ptr<Base_class> b_ptr; shared_ptr<Child_class> ptr((shared_ptr<Child_class&...
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1answer
138 views

Arduino variables loaded from SD card

I am trying to load some variables from an SD card on the start up of my arduino Uno. I have been given some advice but am unable to communicate at the same hours. Using this advice, I have the ...
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1answer
1k views

Arduino: load variables with values read from SD card

I am having a bit of trouble loading values stored on an SD card and assigning them to variables within my program. I can achieve this as one big block of data, but would much prefer them to be saved ...
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2answers
29 views

Comparing custom variable type definitions

In a library I am using with an OBD adapter, they define a public function to get the state of the OBD connection using some strange (and, in my opinion, useless) custom defined variable type: // ...
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3answers
6k views

How can i get rid of the error “cannot convert 'String' to 'const char*'”

I want to get this code to recognise different commands and be able to parse the rest of the command, fore example I send "/sleep 5", and it will sleep for 5 seconds. However, I keep on getting this ...
1
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1answer
70 views

DS18B20 sending variable via Enthernet shield

I am trying to send temperature read from DS18B20 to a web server. I know two things: to read a temperature, and to send something to web server. What I don't know is how to convert float that ...
1
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1answer
2k views

Put integer and double into char array

I want to print text and numbers mixed in a table with Serial.print(); from a char array. My problem is the conversion between the different data types. My idea is to print the data of the rows in a ...
0
votes
1answer
475 views

Store values in array

I'm trying to implement the "BNO055 9 Axes Motion Shield". There is an existing Arduino sketch GitHub that reads out the Euler data, I changed it a bit to print out quaternion data. #include "...
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2answers
4k views

Converting (char*)variable to int

I have the following code: uint8_t buf[1]; uint8_t buflen = 1; if (driver.recv(buf, &buflen)) // Non-blocking { int i; // Message with a good ...
0
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1answer
967 views

RF receiver for integer only, how to cast uint8_t to int?

I'm using the RadioHead library with ASK Driver to transmit/receive data with generic RF modules. It works fine, but I'm lacking some knowledge in programming the code to use the data received. Most ...
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2answers
853 views

How can I write an integer to a Mifare RFID card using the RFID library?

I'm a beginner to C++ and I'm clearly missing some fundamental knowledge of data types. As such, I'm struggling to adapt the examples in the miguelbalboa/rfid library to my use case. I'm simply trying ...
0
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1answer
2k views

Receiving hex data from terminal [closed]

I am trying to transmit serial data from terminal to Arduino and I want to reconfirm that its the same data. But I am not able to get the right answer. I want data to be HEX. I want to check only the ...
1
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2answers
1k views

Const data optimisation for Arduino

I'm taking a course on Arduino Uno programming and on today's talk I heard that the const data is optimized by Arduino, so that it occupies less space than the actual data type (namely, a const int ...
1
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3answers
1k views

Why char 0x80 == 0xFFFFFF80?

As far as I know a char is an 8 bit variable void setup() { Serial.begin(9600); } void loop() { char x = 0x80; if(x != 0x80){ Serial.println(x, HEX); } delay(1000); }
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2answers
836 views

Unable to compare two integer values in Arduino Mega

I wrote Arduino code (code is given at the end) to compare two integer values. The steps I took was: Give input to DC motor to rotate it using serial port. Input was: G254 Then I store it in XX ...
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1answer
2k views

String to unsigned long conversion

I'm trying to use strtoul() to convert an Arduino String to an unsigned long (like the return of millis();) using the following code snippet: unsigned long foo (String time) { unsigned long mili; ...
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1answer
2k views

What is causing this 'narrowing conversion' warning?

Because I'm still figuring out 'Arduino C' I leave all warnings on. Recently I got this one: narrowing conversion of '(int)(((unsigned char)bx_0) | ((unsigned char)bx_1))' from 'int' to 'const byte.....
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2answers
91 views

Arithmetic types in Arduino

I'm looking for a complete list of the arithmetic types in the Arduino framework. On the Internet I found various incomplete lists: sometimes there is short, sometimes word, but other types are ...
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1answer
109 views

Determine whether a variable is of an arithmetic type

Is there a way to determine whether a variable is of an arithmetic type or not? arithmetic: integer, floating point numbers, boolean values not arithmetic: pointers, references; e.g. strings, and ...
1
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2answers
212 views

Is this assignment valid or needs casting?

I have this assignment and while i don't get any error not even warning from the compiler. uint16_t Buffer[40000]; for (int n=0; n<40000 ; n++){ Buffer[n] = (0.99 * cos(((2.0*PI)/40000)*n); } ...
3
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2answers
2k views

inttypes vs Arduino defined integral types

In my Arduino projects I use both Arduino types and types defined in the "inttypes.h" file, which #includes stdint.h. So far I've always written code only for the ATmega328P microcontroller (either in ...
0
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2answers
70 views

character input for an integer variable? [duplicate]

Im trying out the code found here , let me quote the section of code that bothers me. // set pin numbers for switch, joystick axes, and LED: const int switchPin = 2; // switch to turn on and off ...
0
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1answer
404 views

What datatype is the names of the analog inputs?

I am writing a code for an automatic garden, and for this, I will use an array of sensors. I want to represent each plant as a class, and so one of the private variables will then be the sensorID, the ...
8
votes
4answers
24k views

Convert to and from Unix Timestamp

What is the best way to convert between date, hours, min, seconds to Unix timestamp in milliseconds in Arduino? I need to have this conversion, since I'm using RTC (date, hours, min, secs etc) and ...
0
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2answers
128 views

Testing ID and Serial Communication (Update)

Here is my challenge: I have to create a sketch where I would have a prompt asking the user to enter an ID. If it is successful, it would turn on the green LED and response with "Hello, your name is ...
0
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2answers
790 views

Having problems with I2C - Slave is receiving “b ~ ,,,”

so I'm facing a pretty large problem. I'm experimenting with I2C and using one Arduino that acts as a countdown timer to send the current reading on the timer to another Arduino. I'm pretty new to ...
0
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1answer
117 views

Understanding SevSeg

I need to write a library for a display I created with eight segments. So, I decided to try to use SevSeg (https://github.com/DeanIsMe/SevSeg) as a starting off point. It can't be that different, ...
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3answers
575 views

How is a local variable address retrieved/returned inside the CPU of Arduino?

How is the address of a local variable retrieved in Arduino's ATMEGA328 micro-controller? Lets say somewhere inside the main we have lines as: int x = 5; //a variable declared and value of 5 stored ...
2
votes
2answers
117 views

How does an 8bit MCU make use of data-types over 8bits?

how does an 8bit MCU handle 16bit output? How does an 8bit MCU store values higher than 8bits? I am using an attiny, on an adafruit trinket. and other 8bit MCUs. http://www.atmel.com/devices/attiny85....
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1answer
340 views

What is the datatype of the pinMode function?

I just tried it, but the Arduino IDE crashed, I hope its not related. I want to declare a datatype like this: int a = pinMode(pin, OUTPUT); or something like that, but I'm not sure what datatype the ...
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3answers
2k views

What Arduino data type allows decimals?

This probably sounds dumb, but I am not getting any clear answer for this. What data type allows a reasonable amount of decimals?
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2answers
1k views

Writing a float to a BLE characteristic. What data format?

I am currently working on a python-based Bluetooth Low Energy client for OS X and I got stuck while trying to write a remote float characteristic value. First of all: my setup is an Arduino 101 with ...
2
votes
2answers
164 views

How can i do something like multi threathing in arduino?

I am checking for ways to implement multi threathing in Arduino, I have also tried using the library TimerOne but it doesn't seem to work, what I'm trying to make is an Arduino application then, every ...
1
vote
1answer
1k views

What does 16u and 128u mean?

The below is a snippet of a code for operating SI4455 Rf module with Arduino. I have some doubts which I'd like to seek some help in clearing. byte numOfBytes = *pSetPropCmd++; if (numOfBytes &...