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nordin59
Joined: 04 Jun 2009
Posts: 3
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| 18F2480 CAN bus and MCP2551 |
 Posted: Mon Jun 08, 2009 8:25 am |
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I'am trying to configure the can bus of the pic 18f2480 with the CAN Transceiver MCP2551.
I'am using a 40Mhz crystal and i would a speed of 250kbits/s.
I'am also using the library functions titled can18xxx8.c and can18xxx8.h
I configured the 3 baud rate registers by using the software that was given by PCM Programmer :MBTime
| Code: | #IFNDEF CAN_USE_EXTENDED_ID
#define CAN_USE_EXTENDED_ID TRUE
#ENDIF
#IFNDEF CAN_BRG_SYNCH_JUMP_WIDTH
#define CAN_BRG_SYNCH_JUMP_WIDTH 1 //synchronized jump width (def: 1 x Tq)
#ENDIF
#IFNDEF CAN_BRG_PRESCALAR
#define CAN_BRG_PRESCALAR 7 //baud rate generator prescalar (def: 4) ( Tq = (2 x (PRE + 1))/Fosc )
#ENDIF
#ifndef CAN_BRG_SEG_2_PHASE_TS
#define CAN_BRG_SEG_2_PHASE_TS FALSE //phase segment 2 time select bit (def: freely programmable)
#endif
#ifndef CAN_BRG_SAM
#define CAN_BRG_SAM 0 //sample of the can bus line (def: bus line is sampled 1 times prior to sample point)
#endif
#ifndef CAN_BRG_PHASE_SEGMENT_1
#define CAN_BRG_PHASE_SEGMENT_1 4 //phase segment 1 (def: 6 x Tq)
#endif
#ifndef CAN_BRG_PROPAGATION_TIME
#define CAN_BRG_PROPAGATION_TIME 0 //propagation time select (def: 3 x Tq)
#endif
#ifndef CAN_BRG_WAKE_FILTER
#define CAN_BRG_WAKE_FILTER FALSE //selects can bus line filter for wake up bit
#endif
#ifndef CAN_BRG_PHASE_SEGMENT_2
#define CAN_BRG_PHASE_SEGMENT_2 2 //phase segment 2 time select (def: 6 x Tq)
#endif
#ifndef CAN_USE_RX_DOUBLE_BUFFER
#define CAN_USE_RX_DOUBLE_BUFFER TRUE //if buffer 0 overflows, do NOT use buffer 1 to put buffer 0 data
#endif |
And my program is :
| Code: | #include <18F2480.h>
#fuses HS,NOPROTECT,NOLVP,NOWDT
#use delay(clock=40M,oscillator=10M)
#include <can-18xxx8.c>
#define put_off output_low
#define put_on output_high
#define can_error pin_C1
#define can_led pin_C3
void main() {
int out_data[8];
int32 tx_id=24;
int1 tx_rtr=1;
int1 tx_ext=0;
int tx_len=8;
int tx_pri=3;
int i;
for (i=0;i<8;i++) {
out_data[i]=0;
}
can_init();
while(1)
{
if ( can_tbe() && (delay_ms(200))
{
i=can_putd(tx_id, out_data, tx_len,tx_pri,tx_ext,tx_rtr);
if (i != 0xFF) {
put_on(can_led);
delay_ms(150);
put_off(can_led));
}
else {
put_on(can_error);
delay_ms(150);
put_off(can_error);
}
}
}
} |
I have the software called NSI527 on my computer in order to check the communication of the CAN bus.
The problem is the pic doesn't send any data. And when i tried to send datas from my pc just for checking the status of the connection, it sends 1 or 2 datas then the software is in mode BUS OFF !!!!
Here is a scheme of my connection:
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Jun 08, 2009 11:02 am |
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| Quote: |
I have the software called NSI527 on my computer in order to check the
communication of the CAN bus. |
What CAN bus adapter hardware is used with the NSI527 program ?
There must be some kind of cable or adapter board that goes between
your PC and your CAN bus board. I assume that it is connected to J1
on your board. Explain how you connect the PC to the CAN bus on your
board. |
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nordin59
Joined: 04 Jun 2009
Posts: 3
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| Posted: Mon Jun 08, 2009 1:14 pm |
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I have on my computer a CAN PCI and the software NSI527.
With Windows Millenium, It allows to send and receive frames on many channels CAN. Both are linked (pic an computer). |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Jun 08, 2009 1:36 pm |
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| Quote: | | I have on my computer a CAN PCI and the software NSI527. |
Is your PC program setup to use standard or extended ID's ?
In your posted code, you are using standard IDs. Make sure
the PC program is setup for the same thing.
| Quote: | int out_data[8];
int32 tx_id=24;
int1 tx_rtr=1;
int1 tx_ext=0;
int tx_len=8;
int tx_pri=3; |
In my test program here, in can_putd(), I set tx_rtr = 0, so I think
you should try that.
http://www.ccsinfo.com/forum/viewtopic.php?t=29627&start=7
| Quote: | while(1)
{
if ( can_tbe() && (delay_ms(200))
{
i=can_putd(tx_id, out_data, tx_len,tx_pri,tx_ext,tx_rtr);
if (i != 0xFF) {
put_on(can_led);
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According to the CAN bus driver here,
| Quote: | | c:\program files\picc\drivers\can-18xxx8.c |
the data type returned by can_putd() is an 'int1'.
| Code: |
int1 can_putd(int32 id, int * data, int len, int priority, int1 ext, int1 rtr) {
// Returns:
// If successful, it will return TRUE
// If un-successful, will return FALSE
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It can only have a boolean value of 1 or 0 (TRUE or FALSE). But in your
code, you are comparing it to 0xFF. You need to fix that. |
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nordin59
Joined: 04 Jun 2009
Posts: 3
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| Posted: Tue Jun 09, 2009 6:23 am |
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Thanks for your help,
Yes, the PC program is setup for using standard IDs.
And i've modified the condition | Code: | if ( i==1 ) {
put_on(can_led);} |
But the problem still not solved. |
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