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Two Nodes on CAN BUS

 
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swagistan



Joined: 10 Jan 2014
Posts: 2

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Two Nodes on CAN BUS
PostPosted: Fri Jan 10, 2014 10:16 am     Reply with quote
Hello,
I am relatively new to PIC programming. I have some experience in writing C code.
Currently I am trying to build the CAN BUS and using two nodes (A and B).

Objective:
I want to be able to press a button on node a and turn on led on node b, then press the button on node b and turn on led on node A.

I am able to get this code to turn on led on only one side, and am struggling for a week now. Any guidance will be appreciated.

Version of my Compiler: 5.016
PIC Microcontroller: PIC18F2580 for both nodes
Standard Run Mode
Target voltage: 5V system
Target oscillator speed: 20MHz

Here is the code I have for the Node A...
Code:

#include <18F2580.h>
#fuses H4,NOPROTECT,NOLVP,NOWDT
#use delay(clock=20000000)

#include <can-18xxx8.c>

#define PIN_LED1 PIN_B0 // LED PIN

#define BUTTON PIN_B4 ///Here is a change, use pin B4
#define BUTTON_PRESSED  !input (BUTTON)

#define LED1_HIGH output_low(PIN_LED1)
#define LED1_LOW  output_high(PIN_LED1)

#define WRITE_REGISTER_C_ID 0x300
#define WRITE_REGISTER_D_ID 0x18FEDF00


void main()
{
int buffer[8];
int i;
int32 rx_id;
int a_leds=0;
struct rx_stat rxstat;
int rx_len;



setup_adc_ports(AN0_ANALOG);
setup_adc(ADC_CLOCK_INTERNAL);
set_adc_channel(0);
     
      for(i=0;i<8;i++)
      {
         buffer[i]=0;
      }
     
      can_init();
     
while(True)
      {
        if (can_kbhit())
        {
        if (can_getd(rx_id, &buffer[0], rx_len, rxstat));
         if(rx_id == 0x400)
         {
            a_leds=(buffer[0]);
            if(bit_test(a_leds,0))
            {
               LED1_HIGH;
            }
            else
            {
                LED1_LOW;
            }
          }
         } continue;
      }
continue;

if (BUTTON_PRESSED)
            {
              buffer[0]=0xF0;
              delay_ms(10);
            }
            else
            {
              buffer[0]=0xFF;
            }
     
         can_putd(0x300, &buffer[0],1,1,1,0);
     
         i=read_adc();
         delay_ms(1);
         buffer[0]=0xAA;
         buffer[1]=i;
         buffer[2]=0xBB;
     
         can_putd(0x18FEDF00, &buffer[0], 3, 1, 1, 0);}




NODE B:
Code:

#include <18F2580.h>
#fuses H4,NOPROTECT,NOLVP,NOWDT
#use delay(clock=20000000)

#include <can-18xxx8.c>

#define PIN_LED1 PIN_B0 // LED PIN

#define BUTTON PIN_B4 ///Here is a change, use pin B4
#define BUTTON_PRESSED  !input (BUTTON)

#define LED1_HIGH output_low(PIN_LED1)
#DEFINE LED1_LOW  output_high(PIN_LED1)

#define WRITE_REGISTER_A_ID 0x400
#define WRITE_REGISTER_B_ID 0x12BADF00


void main()
{
int buffer[8];
int i;
int32 rx_id;
int a_leds=0;
struct rx_stat rxstat;
int rx_len;


      setup_adc_ports(AN0_ANALOG);
      setup_adc(ADC_CLOCK_INTERNAL);
      set_adc_channel(0);
     
      for(i=0;i<8;i++)
      {
         buffer[i]=0;
      }
     
      can_init();
       
while(TRUE)
       {  if (BUTTON_PRESSED)
            {
           
              buffer[0]=0x00;
              delay_ms(10);
            }
            else
            {
              buffer[0]=0x11;
            }
         
         can_putd(WRITE_REGISTER_A_ID, &buffer[0],1,1,1,0);
     
         i=read_adc();
         delay_ms(1);
         buffer[0]=i;
         buffer[1]=0xBB;
         buffer[2]=0xCC;
         can_putd(WRITE_REGISTER_B_ID, &buffer[0], 3, 1, 1, 0);
         }
 while(TRUE)
     
      {
        if (can_kbhit())
        {
         can_getd(rx_id, &buffer[0], rx_len, rxstat);
         if(rx_id == 0x300)
         {
            a_leds=(buffer[0]);
            if(bit_test(a_leds,0))
            {
               LED1_HIGH;
            }
            else
            {
                LED1_LOW;
            }
         }
         
        }
       
      } }   



I am using PCAN-VIEW to see the messages on the BUS. I am able to see the messages from Node B to A, but not from Node A and when I press the button on Node A... nothing happens on Node B.

Help!
alan



Joined: 12 Nov 2012
Posts: 356
Location: South Africa

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PostPosted: Fri Jan 10, 2014 10:34 am     Reply with quote
In your NODE A code you never get to the BUTTON statement. You sit in a forever while loop;

Regards
swagistan



Joined: 10 Jan 2014
Posts: 2

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PostPosted: Fri Jan 10, 2014 10:46 am     Reply with quote
Hi Alan,
Thanks for the feedback. I originally had two while loops and same issue. Then i changed this to the if statement, but still see the same problem...

I may be missing something very simple. Would you advise do i need to change something in Node B as well? for this to work?
alan



Joined: 12 Nov 2012
Posts: 356
Location: South Africa

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PostPosted: Fri Jan 10, 2014 11:04 am     Reply with quote
You never exit your while loop, so your if loop never evaluates, so can't send a message.
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