char and char x[] i don't understand the behavior of that

Using Arduino Programming Questions
#1

hello ,
few days ago i did post to get some help on a CRC calculation and i did maneged to include a peace of code in my own code...

now i have some trouble with the char value ,i'm really a newbie so i'm sure that's not a bug but a real missundertanding of the programing language

'im able to control the LUT colors by changing the variable declaration in void( setup) but i don't know how to change that in void (loop) on demand:

void setup()
{
  Serial.begin(57600);
  mouse_one.initialize();
  mouse_one.set_scaling_1_1();
  pinMode(13, OUTPUT);      // sets the digital pin as output
   delay (8000);
  
char Header [3] = {
0x6E,0x00,0x00};
char Function [1] = {
0x10}; 
char ByteCount [2] = {
0x00,0x02};  //02
char CRC1[6] ={
Header[0],Header[1],Header[2], Function[0],ByteCount[0], ByteCount[1]};
char Data[2] ={
0x00,0x0B};
char CRC2[2] ={ 
Data[0],Data[1]};



  switch (colors_LUT) 
  {
case 1://rainbow  
     {        
    char Function [1] = {
    0x10};                     
    char ByteCount [2] = {
    0x00,0x02};  //02
    char Data[2] ={
    0x00,0x0B};
     }
 break; 
case 2://sepia  
{
    char Function [1] = {
    0x10}; 
    char ByteCount [2] = {
    0x00,0x02};  //02
    char Data[2] ={
   0x00,0x07}; 

  }



  if (transmit == 0)
  {
  //Serial.println("transmit");// rainbow colors sentence :6E,$00,$00,$10,$00,$02,$BC,$9A,$00,$0B,$B1,$6B
  crc_out1 = calc_crc(CRC1,6); //Calculate CRC on-the-fly 
  crc_out2 = calc_crc(CRC2,2); //Calculate CRC on-the-fly 
 
 Serial.write( (uint8_t*)Header, sizeof(Header)); //why need -3 ??
 Serial.write( (uint8_t*)Function, sizeof(Function));
 Serial.write( (uint8_t*)ByteCount, sizeof(ByteCount));
 
 //crc2 calculated manualy
 //Serial.write(188);
 //Serial.write(154);
 Serial.write(crc_out1 >> 8);     //MSB
 Serial.write(crc_out1 & 0xFF);  //LSB

 Serial.write( (uint8_t*)Data, sizeof(Data)); 

//CRC2 cxalculated manualy
 //Serial.write(177);
 //Serial.write(107); 
 Serial.write(crc_out2 >> 8);     //MSB
 Serial.write(crc_out2 & 0xFF);  //LSB
// Serial.write(10);  //CR
// Serial.print(transmit);
 transmit =1 ;
  }

ok so i would like to be able to change the color LUT of my thermal camera with the select case but i have no idea how to change the values in my char buffer, i know this is a bad way to do that:
char Function [1] = {
0x10};
char ByteCount [2] = {
0x00,0x02}; //02
char Data[2] ={
0x00,0x0B};

but i would like to be able to change that values so i can send to serial port other values . and if it is possible to even write ,for example in Data[2] the two bytes as an integer (keeping the two byte to be send) it is even better ex: 000B = B

is there a way to do so, is there some advance documentation about variable (i'm kind of lost...)?

Moderator edit: quote tags swapped for code tags

#2

You haven't posted your loop function, but variables declared inside setup are not visible to any other function.
Declare the variables outside of functions to give them global scope.

#3

sorry i didn't post the whole code because it is a big mess (learning) if you want it i can post it...

but i also try to declare that before the setup, what i don't know is the syntax to change the value char [x] {0x00,0x0B] in my loop

Moderator edit: code tags again.

#4

You can do it one array element at a time, or you can use memcpy.

#5

sorry for the code tag!

one array element at a time sounds good:

will it be something like so?

Data[1] = 0x0B;
Data[2] = 0x00;
#6

Yes, but don't forget indices start at zero, not one.

#7

oh yes of course, thanx i'll try right away.

#8

ok it works very well:

if(Mdata[0]==9)
  {
    clic=0;
    Mdata[0]= 0; //mouse data
   }
  
    
    Data[0] = 0x00;   //type of color  White hot Black hot Fusion Rainbow Globow Ironbow1 Ironbow2 Sepia Color1 Color2 Ice and fire Rain Custom #1
    Data[1] = page;      //from 0 to 12
    
  }//wend
#9