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Multidimensional array RAM location

 
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murgui



Joined: 23 Dec 2015
Posts: 37

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Multidimensional array RAM location
PostPosted: Wed Jul 06, 2016 7:33 am     Reply with quote

Hi,

I'm using the PIC 18f2685 and my compiler version is 4.114.
I'm programming a system that monitors temperatures. The information is organized in a 3 dimensional array:

T[location][Part1/Part2][sensor]
Being location the place where it's read. Part1/Part2 each of the 2 bytes that conform the temperature and finally sensor the number of sensor of that location:

25,12ÂșC in the first location by the first sensor would be:

T[0][0][0]=12;
T[0][0][0]=25;

All this information is received from 7 Slave PCBs, finally all the information is organized as mentioned before in T[a][b][c].

My doubt comes when using the can_putd function for retransmitting this information to an external data acquisition system. I don't know how does the PIC internally organizes the information and so if my code is fine.


Code:
#include <Master.h>
#define LED PIN_B7
int8 temp[7][2][6];
int8 adr[7] = {0xA1,0xAB,0xB5,0xBF,0xC9,0xD3,0xDD};
int8 n,i,Dir,cont,subcontador,stack=0,s,;
int32 cid=0x320;//cobid base de temperatura

void lectura(int8 Dir);
void escritura();
void canrx0_int();

void main(){
   if(1==1){//CAN ini
   can_init();
   disable_interrupts(GLOBAL);
   can_set_mode(CAN_OP_CONFIG);
   BRGCON1.brp=1;
   BRGCON1.sjw=1;
   BRGCON2.prseg=2;
   BRGCON2.seg1ph=7;
   BRGCON2.sam=FALSE;
   BRGCON2.seg2phts=FALSE; 
   BRGCON3.seg2ph=6;
   BRGCON3.wakfil=FALSE;
   can_set_mode(CAN_OP_NORMAL);
   enable_interrupts(int_canrx0);
   enable_interrupts(int_canrx1);
   enable_interrupts(int_cantx0);
   enable_interrupts(int_cantx1);
   enable_interrupts(int_cantx2);
   enable_interrupts(GLOBAL);}
 
   while(1){
      for (n=0;n<7;n++){
         lectura(adr[n]);}
      if (cont=1){
         cont=0;
         escritura();}
      delay_ms(5);//tiempo por ciclo, optimizar.
   }
}

void lectura(int8 Dir){//I2C Enlace

   i2c_start();
   i2c_write(Dir);// direccion de slave & slave->Master(1)

   for (i=0;i<6;i++){
      temp[n][1][i]=i2c_read(1);
      temp[n][2][i]=i2c_read(1);}
   
   temp[n][1][6]=i2c_read(1);
   temp[n][2][6]=i2c_read(0);
   i2c_stop();
   }
   
void escritura(){//envio de mensajes por CAN
   if (stack==7){
      stack=0;}
   
   [b]can_putd(cid+stack*10,&temp[stack][0][0],8,FALSE,FALSE);
   can_putd(cid+stack*10+1,&temp[stack][1][2],4,FALSE,FALSE);[/b]
   stack++;
   }

#int_canrx0
void canrx0_int ( ) {//Deteccion mensaje sincronismo
   cobid=((unsigned int16)RXB0SIDH << 3)|((RXB0SIDL & 0xE0)>>5);
   
   lengthCAN = (unsigned int8)RXB0DLC & 0xF;
   
   if (cobid == 0x80){
      subcontador++
      if (subcontador==20){
         cont=1;
         subcontador=0;
      }
   }
}


Is the can_putd system correct? The information will be transmitted correctly?
I'm afraid the written code will send the information haphazardly. I want it to send
Thank you very much,

Murguizur.


Last edited by murgui on Wed Jul 06, 2016 8:42 am; edited 1 time in total
Ttelmah



Joined: 11 Mar 2010
Posts: 19539

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PostPosted: Wed Jul 06, 2016 8:38 am     Reply with quote

This is actually a C question not CCS!.... Very Happy

C stores things in 'row major' order in memory.

So if you have an array [x][y][z]

Then in memory, you get [X0, Y0, Z0] , [X0, Y0, Z1], ...[X0, Y0, Zmax],
[X0, Y1, Z0] etc.

As you advance through memory, the right hand variable varies first, then the second etc..
murgui



Joined: 23 Dec 2015
Posts: 37

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PostPosted: Wed Jul 06, 2016 8:48 am     Reply with quote

Thank you very much, you were really helpful. I didn't know how to look for this.
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