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CAN Node with PIC16F877A and MCP2515
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girichavana



Joined: 21 Oct 2008
Posts: 17

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CAN Node with PIC16F877A and MCP2515
PostPosted: Thu Aug 06, 2009 8:35 am     Reply with quote
Hi,

I am designing the two CAN nodes with PIC16F877A and MCP2515.

I am using the CCS C libraries:
Code:

#include <can-mcp251x.h>
#include <can-mcp251x.c>

But I am not getting the proper output.
Please verify my code.

Here is my code:

For NODE1:
Code:

#include <16F877A.h>
#fuses HS,NOPROTECT,NOLVP,NOWDT
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)

#define CAN_DO_DEBUG TRUE

#define EXT_CAN_CS   PIN_D1
#define EXT_CAN_SI   PIN_C4
#define EXT_CAN_SO   PIN_C5
#define EXT_CAN_SCK  PIN_C3

#include <can-mcp251x.h>
#include <can-mcp251x.c>

#define PIN_LED1  PIN_A1
#define PIN_LED2  PIN_A2
#define PIN_LED3  PIN_A3

#define LED1_HIGH output_low(PIN_LED1)
#define LED1_LOW  output_high(PIN_LED1)
#define LED2_HIGH output_low(PIN_LED2)
#define LED2_LOW  output_high(PIN_LED2)
#define LED3_HIGH output_low(PIN_LED3)
#define LED3_LOW  output_high(PIN_LED3)

int16 ms;

#int_timer2
void isr_timer2(void) {
   ms++; //keep a running timer that increments every milli-second
}

#define RESPOND_TO_ID_AD   0x201
#define RESPOND_TO_ID_LED  0x202

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

   int i;

   setup_port_a(RA0_ANALOG);
   setup_adc(ADC_CLOCK_INTERNAL);
   set_adc_channel(0);

   for(i=0;i<8;i++) {
      buffer[i]=0;
   }

   LED1_HIGH;
   LED2_HIGH;
   LED3_HIGH;
   printf("\r\n\r\nCCS CAN EXAMPLE\r\n");
   delay_ms(1000);
   LED1_LOW;
   LED2_LOW;
   LED3_LOW;

   setup_timer_2(T2_DIV_BY_4,53,3);

   can_init();

   enable_interrupts(INT_TIMER2);   //enable timer2 interrupt
   enable_interrupts(GLOBAL);       //enable all interrupts (else timer2 wont happen)

   printf("\r\nRunning...");

   while(TRUE)
   {

      if ( can_kbhit() )   //if data is waiting in buffer...
      {
         if(can_getd(rx_id, &buffer[0], rx_len, rxstat))   //...then get data from buffer
       {                   
            if (rx_id == RESPOND_TO_ID_LED)
         {
               printf("Chaning LEDs\r\n\r\n");
               if (bit_test(buffer[0],0)) {LED1_HIGH;} else {LED1_LOW;}
               if (bit_test(buffer[0],1)) {LED2_HIGH;} else {LED2_LOW;}
               if (bit_test(buffer[0],2)) {LED3_HIGH;} else {LED3_LOW;}
            }
            if (rx_id == RESPOND_TO_ID_AD)
         {
               i=read_adc();
               printf("Sending AD reading: %X\r\n\r\n",i);
               can_putd(RESPOND_TO_ID_AD, &i, 1,1,1,0); //put data on transmit buffer
            }
         }
      }
   }
}


For NODE2:
Code:

#include <16F877A.h>
#fuses HS,NOPROTECT,NOLVP,NOWDT
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)

#define CAN_DO_DEBUG TRUE

#define EXT_CAN_CS   PIN_D1
#define EXT_CAN_SI   PIN_C4
#define EXT_CAN_SO   PIN_C5
#define EXT_CAN_SCK  PIN_C3

#include <can-mcp251x.H>
#include <can-mcp251x.c>

#define BUTTON    PIN_A4

#define BUTTON_PRESSED  !input(BUTTON)

#define PIN_LED1  PIN_A1
#define PIN_LED2  PIN_A2
#define PIN_LED3  PIN_A3

#define LED1_HIGH output_low(PIN_LED1)
#define LED1_LOW  output_high(PIN_LED1)
#define LED2_HIGH output_low(PIN_LED2)
#define LED2_LOW  output_high(PIN_LED2)
#define LED3_HIGH output_low(PIN_LED3)
#define LED3_LOW  output_high(PIN_LED3)

int16 ms;

#int_timer2
void isr_timer2(void) {
   ms++; //keep a running timer that increments every milli-second
}

#define ASK_FOR_ID_AD_B      0x201  //ask for AD info from CAN port B
#define SET_LED_ID_B         0x202  //set LEDs for CAN port B

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

   int i;

   setup_port_a(RA0_ANALOG);
   setup_adc(ADC_CLOCK_INTERNAL);
   set_adc_channel(0);

   for(i=0;i<8;i++) {
      buffer[i]=0;
   }

   LED1_HIGH;
   LED2_HIGH;
   LED3_HIGH;
   printf("\r\n\r\nCCS CAN EXAMPLE\r\n");
   delay_ms(1000);
   LED1_LOW;
   LED2_LOW;
   LED3_LOW;

   setup_timer_2(T2_DIV_BY_4,53,3);

   can_init();

   enable_interrupts(INT_TIMER2);   //enable timer2 interrupt
   enable_interrupts(GLOBAL);       //enable all interrupts (else timer2 wont happen)

   printf("\r\nRunning...");

   while(TRUE)
   {
      if ( can_kbhit() )
      {
         printf("\r\n");
         if(can_getd(rx_id, &buffer[0], rx_len, rxstat)) {
            if (rx_id == ASK_FOR_ID_AD_B) {
               printf("Channel B AD: %X\r\n",buffer[0]);
            }
         
         }
      }

      if ( can_tbe() && (ms > 2000))       //every two seconds, send new data if transmit buffer is empty
      {
         ms=0;

         //change leds on port b
         printf("\r\n\r\nSet LEDs on Port B to %U",b_leds);
         can_putd(SET_LED_ID_B, &b_leds, 1, 1, 1, 0);
         b_leds++;
         if (b_leds > 7) {b_leds=0;}
      }

     
   }
}

Thanks and regards.
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Thu Aug 06, 2009 11:11 am     Reply with quote
Your code is too complicated. Try a simple test with two CAN boards
as shown in my post in this thread:
http://www.ccsinfo.com/forum/viewtopic.php?t=29627&start=3
girichavana



Joined: 21 Oct 2008
Posts: 17

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PostPosted: Thu Aug 06, 2009 10:14 pm     Reply with quote
Hi,

Thanks for the reply

How to set my hardware to the LOOPBACK mode.

Its not mentioned in the forum

Thanks and regards
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Thu Aug 06, 2009 11:11 pm     Reply with quote
There's a link to the loopback code, in the link that I posted above.
All you have to do, is to change the #include file for your PIC,
and for the CAN driver. I can't test this in hardware at the moment,
but it will probably work. Change the #define statements for the
pin connections to your MCP2515 chip if they are different than the
connections given below.
Code:

#include <16F877A.h>
#fuses HS, NOWDT, BROWNOUT, PUT, NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)

// *** Change these pins to match your connections ***
#define EXT_CAN_CS   PIN_B1
#define EXT_CAN_SI   PIN_C1
#define EXT_CAN_SO   PIN_C0
#define EXT_CAN_SCK  PIN_C3
#include <can-mcp251x.c>

void main(void)
{
int32 can_id;
int can_data[8];
int can_length, counter;
struct rx_stat rxstat;

can_init();
can_set_mode(CAN_OP_LOOPBACK);
counter = 0;
puts("Starting");

can_data[0] = 0x55;

while(1)
{
 if(kbhit())
   {
    getch();

    if(can_putd(42, can_data, 1, 3, TRUE, FALSE))
       puts("tx ok");

    while(!can_kbhit());
   
    if(can_getd(can_id, &can_data[0], can_length, rxstat))
       puts("rx ok");

    counter++;
   }
}

}
girichavana



Joined: 21 Oct 2008
Posts: 17

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PostPosted: Fri Aug 07, 2009 2:20 am     Reply with quote
Hi,

I am getting the output as follows for the above code

rx ok
Starting
tx ok
rx ok
rx ok
Starting
rx ok
tx ok
rx ok
rx ok
rx ok
rx ok
rx ok
rx ok
rx ok
rx ok
rx ok
rx ok
rx ok
tx ok
rx ok
tx ok

it is getting "rxok" continuously but not the "txok"

I am using the 4MHz for my PIC and 16MHz for my MCP2515

Thanks and regards
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Fri Aug 07, 2009 1:05 pm     Reply with quote
1. Post a list of connections between your PIC and the MCP2515.
Post the actual pin numbers, not just the signal names.

2. Did you build this board yourself, or did you buy the board ?
If bought the board, post the manufacturer and model number.

3. Did you modify the code that I posted ? If so, post the actual code
that you are using for the test.

4. Post your compiler version.
girichavana



Joined: 21 Oct 2008
Posts: 17

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PostPosted: Thu Aug 20, 2009 1:05 am     Reply with quote
Hi,

I don't know how to post the .jpg file.

The board is designed by myself.

I modified the code as follows:
Code:

#include <16F877A.h>

#fuses HS,NOPROTECT,NOLVP,NOWDT
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)

// *** Change these pins to match your connections ***
#define EXT_CAN_CS   PIN_D1
#define EXT_CAN_SI   PIN_C4
#define EXT_CAN_SO   PIN_C5
#define EXT_CAN_SCK  PIN_C3

#include <can-mcp251x.c>

void main(void)
{
int32 can_id;
int can_data[8];
int can_length, counter;
struct rx_stat rxstat;

puts("Can Sample");
can_init();
can_set_mode(CAN_OP_LOOPBACK);
counter = 0;
puts("Starting");

can_data[0] = 0x55;

while(1)
{
    if(kbhit())
      {
       getch();

       if(can_putd(42, can_data, 1, 3, TRUE, FALSE))
             puts("tx ok");

       while(!can_kbhit());
   
       if(can_getd(can_id, &can_data[0], can_length, rxstat))
             puts("rx ok");

       counter++;
    }
}

}

I am using the PCM version 4.068.
PCM programmer



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PostPosted: Thu Aug 20, 2009 1:17 am     Reply with quote
Post the output that you get from that program, during a recent test.
girichavana



Joined: 21 Oct 2008
Posts: 17

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PostPosted: Thu Aug 20, 2009 2:58 am     Reply with quote
Hi,

The following is the output

Can Sample
Starting
tx ok
rx ok
rx ok
tx ok
rx ok
rx ok
tx ok
rx ok
rx ok
rx ok
tx ok
rx ok
tx ok
rx ok
tx ok
rx ok
tx ok
rx ok
rx ok
PCM programmer



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Posts: 21708

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PostPosted: Fri Aug 21, 2009 2:23 pm     Reply with quote
It worked for me. Here's the output. I added some printf statements
at the start of the program to trace the program flow.
Quote:

Can Sample
Can init done
Loopback mode set
Starting
tx ok
rx ok
tx ok
rx ok
tx ok
rx ok
tx ok
rx ok
tx ok
rx ok
tx ok
rx ok
tx ok
rx ok
tx ok
rx ok
tx ok
rx ok
tx ok
rx ok
tx ok
rx ok
tx ok
rx ok

I installed vs. 4.068 of the compiler. I modified a Microchip MCP2510
Development kit board to use a 4 MHz external oscillator for the PIC
(but keeping the 16 MHz oscillator for the MCP2510).

Also, I didn't have a MCP2515 so I had to use an MCP2510. In the
mode that we are using in this program, I think they are compatible.
But still, there could possibly be a difference that is causing a problem.
Code:

#include <16F877A.h>
#fuses HS,NOPROTECT,NOLVP,NOWDT
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)

// These connections are for the Microchip MCP2510 Dev. board
#define EXT_CAN_CS   PIN_C2 
#define EXT_CAN_SO   PIN_C4
#define EXT_CAN_SI   PIN_C5
#define EXT_CAN_SCK  PIN_C3

#include <can-mcp251x.c>

void main(void)
{
int32 can_id;
int can_data[8];
int can_length, counter;
struct rx_stat rxstat;

puts("Can Sample");

can_init();
puts("Can init done");

can_set_mode(CAN_OP_LOOPBACK);
puts("Loopback mode set");

counter = 0;
puts("Starting");

can_data[0] = 0x55;

while(1)
{
    if(kbhit())
      {
       getch();

       if(can_putd(42, can_data, 1, 3, TRUE, FALSE))
             puts("tx ok");

       while(!can_kbhit());
   
       if(can_getd(can_id, &can_data[0], can_length, rxstat))
             puts("rx ok");

       counter++;
    }
}

} 
girichavana



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Posts: 17

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PostPosted: Fri Oct 16, 2009 7:34 am     Reply with quote
After a long time again I started to fight with the CAN.

My board is not answering properly for the loopback mode.

Is it needs any pullups for the IO lines b/w the PIC and the MCP2551?

Thanks
PCM programmer



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Posts: 21708

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PostPosted: Fri Oct 16, 2009 12:42 pm     Reply with quote
Quote:
Is it needs any pullups for the IO lines b/w the PIC and the MCP2551?

The PIC doesn't connect to the MCP2551 transceiver. The PIC connects
to the MCP2515 controller. The connections look like this:
Code:
PIC <---> MCP2515 <---> MCP2551 <---> CAN bus cable

Also, in LOOPBACK mode, the MCP2515 controller doesn't use any
external components. The MCP2551 transceiver is not required.
See the MCP2515 data sheet:
http://ww1.microchip.com/downloads/en/DeviceDoc/21801e.pdf
Quote:
10.4 Loopback Mode

The Loopback mode is a silent mode, meaning no
messages will be transmitted while in this state
(including error flags or acknowledge signals).
The TXCAN pin will be in a recessive state.
girichavana



Joined: 21 Oct 2008
Posts: 17

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PostPosted: Sat Oct 17, 2009 11:26 pm     Reply with quote
Sry,

I connected PIC to MCP2515 only. By mistake I entered MCP2551 instead of MCP2515.

With the above program I am not getting the CAN Initializing properly.

It is giving the output as follows.

Can Sample

<here it is waiting for a long time, if I touch the soldering side of the board at the MCP2515 then it is giving the below sentence>

Can init done
Loopback mode set
Starting

<Now I am pressing the keys in my PC, for the each key press it is not giving the txok and rxok strings, it is giving randomly as follows >

txok
rxok
txok
rxok
txok
rxok
rxok
txok
rxok
txok
rxok
rxok

like it is giving only rxok for a key press.

Thanks
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Sun Oct 18, 2009 3:21 pm     Reply with quote
Quote:

If I touch the soldering side of the board at the MCP2515 then it is giving
the below sentence.

1. What is connected to the \RESET pin on the MCP2515 ? Describe
the circuit.

2. Describe the connections to the OSC1 and OSC2 pins on the MCP2515.
What components are connected to those pins ? What are their values ?

Or, post a link to the schematic for your board.
girichavana



Joined: 21 Oct 2008
Posts: 17

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PostPosted: Tue Oct 20, 2009 6:03 am     Reply with quote
I am giving the link to my circuit pls verify it

http://tinypic.com/r/1zohr2b/4
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