全局变量arduino [英] Global variable arduino
问题描述
我使用 I2C 将 Arduino 主控与 4 个从属 Arduino 通信,并在每个 Arduino 从属设备上连接一个 Shield (OULIMEX Shield LCD 16x2).我使用 I2C 将数据从主机发送到从机.所以我在 master 中使用了这段代码:
I'm using I2C to communicate a Master Arduino to 4 Slaves Arduinos, and an Shield (OULIMEX Shield LCD 16x2) on every Arduino slave. I send Data from the master to slaves using I2C. So I use this code in the master :
#include <Wire.h>
#include <math.h>
#include <floatToString.h>
double incomingData;
void setup()
{
Wire.begin();
Serial.begin(9600);
incomingData = Serial.parseFloat(); //read incoming data
}
void loop()
{
delay (1000);
if (Serial.available())
{
incomingData = Serial.parseFloat(); //read incoming data
Wire.beginTransmission(8); // transmit to device #8
if ((M==0) || (M==1) || (M==2))
Wire.beginTransmission(8); // transmit to device #8 *****************************************************************
else
Wire.beginTransmission(7); // transmit to device #7 *****************************************************************
M++;
if (M==5)
M=0;
String a = "";
a = floatToString(test,incomingData,3,5,true);
for(i=0; a[i]!='\0'; ++i); // length of the string
Wire.write(i);
Wire.write(floatToString(test,incomingData,3,5,true)); // sends one byte
Wire.endTransmission(); // stop transmitting
}
}
我希望将数据打印在 Shield 上,但我正在以相同的方式将所有从设备与主设备连接起来.为此,我有两个问题:
I wanted the Data to be printed on the Shield, but I'm connecting all slaves with the same way with the master. For that I have two problems :
1- 我用来打印值的全局数据总是打印为 0,而不是给出实际值;
1- The global data I'm using to print value is always printed as 0, and not giving the real value;
2- 所有 Shield 都打印相同的内容:例如,我在第一个 Shield 中打印hello",在第二个 Shield 中打印hi",但是 both 打印相同的内容(hello 或 hi).
2- All Shields print the same thing : For exemple, I print "hello" in the first Shield, and I print "hi" in the second Shield, but bouth are printing the same thing (hello or hi).
第一个从站使用的代码是:
The code using for the first slave is :
#include <LCD16x2.h>
#include <Wire.h>
LCD16x2 lcd;
int buttons;
int sensorPin = A0; // select the input pin for the potentiometer
int sensorValue = 0; // variable to store the value coming from the sensor
float numOut;
int comp=1 ;
String wordd = "";
int M =0;
void setup()
{
Wire.begin(8); // join i2c bus with address #8
Wire.onReceive(receiveEvent); // register event
Serial.begin(9600); // start serial for output
}
void loop()
{
delay(500);
}
// function that executes whenever data is received from master
// this function is registered as an event, see setup()
void receiveEvent(int howMany) {
wordd = "";
int x = Wire.read();
for (int i=0; i<=x; i++)
{
char c = Wire.read();
wordd += c;
}
numOut = wordd.toFloat();
Serial.println(numOut,3); // print the integer
}
提前谢谢你!!
推荐答案
这个问题我已经问过了,但我想我已经有了答案.必须在 void 设置和 void 循环之前声明一个全局变量,如下所示:
I already ask this question but I think I have the answer of it. A global variable have to be diclared befor the void setup, and the void loop too, like that :
type YourGlobalVariable;
void setup()
{
}
void loop()
{
}
所以,这正是我所做的.它对我不起作用的原因是我使用了这个功能:
So, it is exactly how I did already. The reason it didn't work for me, it was cause of I used this function :
void receiveEvent(int howMany) {}
我真的不知道它的哪些属性让它不适用于全局变量,但它就像我已经说过的那样工作.
I don't really know what are the properties of it that let it not work for a global variables, but It works like I sayd already.
谢谢大家
这篇关于全局变量arduino的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!