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`.
119
questions
2
votes
2
answers
527
views
Read one byte from file and convert to decimal
Ok, I'm fairly new to Arduino and I'm trying to read bytes from a file in an SD card and convert to integer values (0-255).
I have a file, with 1 byte on it (128 int value, created in Python, can ...
- 71
0
votes
4
answers
409
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
vote
1
answer
541
views
Wire.write invalid conversion from ‘char*’ to ‘const uint8_t*
I have written this code:
char message[4];
memcpy(message, &delta, 4);
Wire.write(message, 4);
When I try to compile I get this warning:
warning: invalid conversion from ‘char*’ to ‘const ...
- 33
0
votes
1
answer
101
views
Conversion from `const char* datac="0x21,0x10,0xfa,0x7a,0xff";` to `uint8_t datat[]={0x21, 0x10, 0xfa, 0x7a, 0xff}`
The below reading data from API:
#include <WiFi.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>
const char* ssid = "****";
const char* pass = "****";
void ...
0
votes
2
answers
187
views
String() vs char for simple flow control
I am newbie in Arduino and writing a program where I want to control the flow by using Serial monitor input (PI controller).
I've read that using String() although easier it is slower than using char. ...
0
votes
1
answer
122
views
What's the difference between CloudTemperature, CloudTemperatureSensor and Float data types?
I have a SHT30 sensor for Wemos and I am learning to use Arduino IOT Cloud.
I use float data type for my temperature variable but I see two more data types:
CloudTemperature
CloudTemperatureSensor
...
- 448
1
vote
1
answer
558
views
How to know the data type of constant in arduino IDE?
For example constant of MSBFIRST, It used to as input in SPI.setBitOrder(MSBFIRST). But sadly i don't know the type data of MSBFIRST. This is applied to like SPI_MODE0 and other.
2
votes
1
answer
250
views
Arduino data-types
(Im new to the arduino side of stackexchange). Im working on a worksheet for to begin with arduino. I have prior experiences working with arduinos, but problem is new for my field of expertise. Any ...
- 23
1
vote
1
answer
615
views
Store Integer Value of Money on an RFID Tag
I am working on making an Arduino based arcade. I want each user of the arcade to have an RFID card that stores the amount of credits (basically money) they have. I know that RFID tags have 1028 bytes ...
- 113
2
votes
1
answer
144
views
Conditional compilation depending on sizeof(double)
Is there a macro (#define ...) somewhere in the bowels of Arduino IDE or core header files which tells me at compile time(!), if the double data type for a given platform/board is a true double ...
- 123
-2
votes
1
answer
497
views
Converting an int to an unsigned char for display on a Nokia 5110
I've been working on a small project getting some images displayed in a Nokia 5110 screen via an Arduino. I've been getting it working, but one of the issues I have is that I would like to have a list ...
- 105
1
vote
0
answers
738
views
converting int or float into bytes array in arduino
I am trying to send data from one arduino to another over ethernet using udp protocol.
In arduino writing data over udp is like this
UDP.write(buffer, size);
where buffer is an array to send as a ...
0
votes
1
answer
157
views
What is the purpose of putting a data type in brackets before a calculation?
sorry for the nooby question but I can't seem to find the answer to this anywhere, probably because I'm unsure what to search for with this problem!
I'm just wondering what the reason is for including ...
- 3
1
vote
0
answers
940
views
incompatible types in assignment of 'const String' to 'char [32] using server.arg
I am trying to create a class and getting getting the error
incompatible types in assignment of 'const String' to 'char [32]
when I declare
char inString[32];
and try to set it as
inString = server....
- 201
1
vote
1
answer
93
views
Import into Arduino a vintage data bus from TMS1000
For experimentation I want to import or receive into Arduino the output data from a TMS1000 (1980s) data bus. For model train controller Hornby Zero1, and the bus sends data to receivers, for loco ...
- 11
1
vote
1
answer
307
views
Why use \" in arduino code?
While working with JSON parsing I noticed that the char type data string is written like this:
char json[] = "{\"sensor\":\"gps\",\"time\":1351824120,\"data\&...
- 117
2
votes
2
answers
559
views
Not output on serial monitor, sending string on serial.print
I get two 10-bit values from analog pins. These two values in a string, ";" combine with.
for ex: 515; 510
I am sending it to another arduino via Serial.print. I cannot display this string ...
- 81
2
votes
2
answers
2k
views
Own type definition using a struct does not name a type
I need to initialize several buttons and LEDs connected to my Arduino. To store data related to an individual button or LED, I decided to define my own data type using two different structs. One for a ...
- 205
-1
votes
1
answer
203
views
storing 600 unsigned int values in an array and find minimum and maximum values
I am reading an ASCII serial data values from a sensor and storing it in an unsigned integer variable. The values are ~45000 to 50000 range. I need to store 600 values and then find the minimum and ...
- 1
2
votes
1
answer
10k
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 ...
0
votes
1
answer
295
views
Assigning value to a struct byte order
So i have struct:
typedef struct sendPacketStruct {
byte header = headerByte;//0x55
unsigned int time;//2 bytes
int height;//2 bytes
};
And i do this:
sendPacketStruct sendPacket;
...
- 308
0
votes
1
answer
439
views
AccelStepper library advanced codes!
I was trying to find out how this library can run multiple stepper motors at the same time, and I saw this important function called...
void AccelStepper::setOutputPins(uint8_t mask)
{
uint8_t ...
- 149
-3
votes
1
answer
1k
views
Any limitation on array size in Arduino Mega 2560?
I am writing an Arduino code with 3 arrays.
Two of those are double and other one is int. Further first two arrays have nearly 420 elements for each.
Now I noticed that with more that 89 elements on ...
- 1
1
vote
1
answer
351
views
What else is consuming Data Segment reported by avr-size?
I am facing a low memory available problem in arduino. I am compiling a big sketch for arduino mega 2560.
Analysing a .elf file, the avr-size tool gives:
text data bss dec hex filename
...
- 13
1
vote
1
answer
947
views
Int64_t aka long long acts as int32_t and overflows at 2^31
I have an int64_t variable. When I add another int64_t variable
and convert it to a double to print it on the serial monitor, it acts as if it was a int32_t variable. This is the program:
int64_t a =...
- 295
1
vote
0
answers
344
views
ModbusMaster - Read 64 Bit integer
i'm using ModbusMaster library (Repo) to read from a device some registers.
Many of them are float and i've no problem to read them using the following code:
//for float conversation
union
{
...
- 167
1
vote
1
answer
160
views
Data type explanation regarding analogRead of a photoresistor
This is a fundamental question - very new (1st post) and trying to learn. I have a photocell connected in series with a 10kOhm resistor between 5v & Gnd (to make a voltage divider) and the ...
- 13
0
votes
1
answer
2k
views
How to convert four uint16_t to double float IEEE754?
I am working in a Modbus project where I have to read modbus Holding and Input registers using ESP8266, I am using ModbusMaster232 library. I returns a response buffer array of uint16_t. I need to ...
- 67
0
votes
1
answer
117
views
Boolean function call with character pointer input - dont understand how to get updated pointer value
Thank you for everyone's help in trying to find a solution. This library I'm working with was prewritten and is one of the most buggy hardware libraries I've had the misfortune to use. I have now ...
- 13
3
votes
4
answers
628
views
Can I use 1-byte datatypes to store digital input?
I am reading the docs on DigitalRead() and wondering why it stores seemingly boolean HIGH and LOW inputs in int data type variable.
I have two issues with that:
int is 2-byte, while bool and ...
- 145
-1
votes
1
answer
388
views
Keyboard.write writing ASCII integer value as a String
I have the following code:
#include <SoftwareSerial.h>
#include <Keyboard.h>
SoftwareSerial ttySerial(10, 11); // RX, TX
void setup()
{
// Open serial communications and wait for port ...
- 109
1
vote
2
answers
988
views
Why does Arduino IDE recommend storing 0-255 numbers in "byte" instead of "char"?
I bumped into byte datatype recently. My knowledge of C/C++ is shallow, but I know char and I couldn't find much on byte in C++ docs. I looked it up in the Arduino docs:
It’s recommended to only ...
- 145
1
vote
1
answer
1k
views
cast double to long leads to unexpected results
I wrote a little program to show my problem:
void setup()
{
Serial.begin(9600);
double K=39.85;
double a=K*100;
Serial.print("a= ");
Serial.println(a);
long val_long = 0;
val_long = ...
- 19
1
vote
3
answers
4k
views
Set and extract individual bytes of a number (lowByte() and highByte())
You can extract
the low-order (rightmost) byte of a variable
or
the high-order (leftmost) byte of a word
with the functions lowByte() and highByte() respectively (the quotes are from the ...
- 295
0
votes
2
answers
348
views
What is the best data type to be used through i2C
i'm trying to send multiple commands to multiple slaves controlling motors. Slave Controller(Arduino Nano) will receive the command, and returns the current position of the motors to the Master(...
- 91
0
votes
1
answer
159
views
What kind of data type can be use store a binary bit-stream which is more than 64-bits?
I'm wondering if one needs to assign a bit-stream of 78 bits to a variable(later on to be processed), what datatype can be used? What is the max bit can be stored into a variable in C?
- 245
0
votes
2
answers
147
views
What are the sizes of each primitive datatype on a Metro M4 Express SAMD51?
What are the data sizes of all the primitive datatypes on a Metro M4 Express SAMD51 C++ implementation? In some C++ implementations, int has 16 bits and in other implementations it has 32 bits. Is
- 113
2
votes
1
answer
124
views
double to char* conversion. Weird results from dtostrf
Here’s the code:
void setup()
{
Serial.begin(9600);
delay(300);
double lat = 1111.11;
double lon = 4444.44;
const byte len{10};
char sLat[len];
char sLon[len];
...
- 439
1
vote
2
answers
514
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 ...
- 129
0
votes
1
answer
43
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="+...
- 105
1
vote
0
answers
168
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 ...
- 79
0
votes
1
answer
996
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 ...
1
vote
1
answer
334
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 ...
- 61
3
votes
1
answer
3k
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
...
- 173
0
votes
2
answers
199
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 ...
- 993
0
votes
1
answer
181
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 <...
- 41
0
votes
1
answer
3k
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 ...
- 131
0
votes
2
answers
2k
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]);
...
- 161
0
votes
1
answer
392
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,...
- 11
1
vote
0
answers
213
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 ...
- 422