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quad3
Joined: 23 Jan 2007
Posts: 5
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| CAN - can_putd |
 Posted: Tue Jun 05, 2007 5:41 am |
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Hi,
I'm trying to get 2 PIC to communicate with each other via CAN.
The ouput from 1 PIC is from PC (character from keyboard) using this char
| Code: | char out_data;
out_data = getchar();
printf("\r\n\n you pressed %c", out_data); |
but data in CAN messages are int
| Code: | int1 can_putd(int32 id, int * data, int len, int priority, int1 ext, int1 rtr) {
int i;
int * txd0;
int port; |
My question is, how do I display the correct data at the receiving node? For example if I key in the letter 'a' at keyboard, the letter 'a' will be displayed at the receiver's terminal.
Here are the two codes that I'm using:
1. Transceiver
| Code: | #include <18F458.h>
#fuses XT,NOPROTECT,NOLVP,NOWDT
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7) // Jumpers: 8 to 11, 7 to 12
#include <can-18xxx8.c>
int16 ms;
#int_timer2
void isr_timer2(void) {
ms++; //keep a running timer that increments every milli-second
}
#define SEND_TO_PORT_B 0x201
#define SEND_TO_PORT_C 0x202
void main() {
char out_data;
int1 tx_rtr=1;
int1 tx_ext=0;
int tx_len=8;
int tx_pri=3;
int i;
printf("\r\n\r\nCCS CAN EXAMPLE\r\n");
setup_timer_2(T2_DIV_BY_4,79,16);
can_init();
can_set_mode(CAN_OP_NORMAL);
enable_interrupts(INT_TIMER2);
enable_interrupts(GLOBAL);
printf("\r\nRunning...");
while(TRUE)
{
if ( can_tbe() && (ms > 500))
{
printf("\r\n\Transmit buffer ready");
out_data = getchar();
printf("\r\n\n you pressed %c", out_data);
ms=0;
//Data for Port B
if (out_data=='a' || out_data=='b' || out_data=='c'){
i=can_putd(SEND_TO_PORT_B, out_data, tx_len,tx_pri,tx_ext,tx_rtr); //put data on transmit buffer
if (i != 0xFF) { //success, a transmit buffer was open
printf("\r\nSend data to Port B");
printf("\r\nPUT %U: ID=%LU LEN=%U ", i, SEND_TO_PORT_B, tx_len);
printf("PRI=%U EXT=%U RTR=%U\r\n DATA = ", tx_pri, tx_ext, tx_rtr);
for (i=0;i<tx_len;i++) {
printf("%c ",out_data);
}
printf("\r\n");
}
else { //fail, no transmit buffer was open
printf("\r\nFAIL on PUTD\r\n");
}
}
//Data for Port C
if (out_data=='d' || out_data=='e' || out_data=='f'){
i=can_putd(SEND_TO_PORT_C, out_data, tx_len,tx_pri,tx_ext,tx_rtr); //put data on transmit buffer
if (i != 0xFF) { //success, a transmit buffer was open
printf("\r\nSend data to Port B");
printf("\r\nPUT %U: ID=%LU LEN=%U ", i, SEND_TO_PORT_C, tx_len);
printf("PRI=%U EXT=%U RTR=%U\r\n DATA = ", tx_pri, tx_ext, tx_rtr);
for (i=0;i<tx_len;i++) {
printf("%c ",out_data);
}
printf("\r\n");
}
else { //fail, no transmit buffer was open
printf("\r\nFAIL on PUTD\r\n");
}
}
}
}
} |
2. Receiver
| Code: | #include <18F458.h>
#fuses XT,NOPROTECT,NOLVP,NOWDT
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7) // Jumpers: 8 to 11, 7 to 12
#include <can-18xxx8.c>
int16 ms;
int i;
#int_timer2
void isr_timer2(void) {
ms++; //keep a running timer that increments every milli-second
}
#define DATA_FROM_A 0x201
void main() {
struct rx_stat rxstat;
int32 rx_id;
char in_data[8];
int rx_len;
printf("\r\n\r\nCCS CAN EXAMPLE\r\n");
setup_timer_2(T2_DIV_BY_4,79,16); //setup up timer2 to interrupt every 1ms if using 20Mhz clock
can_init();
can_set_mode(CAN_OP_NORMAL);
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...
{
printf("\r\nData in receive buffer");
if(can_getd(rx_id, &in_data[0], rx_len, rxstat)) { //...then get data from buffer
if (rx_id == DATA_FROM_A) {
printf("\r\nGOT: BUFF=%U ID=%LU LEN=%U OVF=%U ", rxstat.buffer, rx_id, rx_len, rxstat.err_ovfl);
printf("FILT=%U RTR=%U EXT=%U INV=%U", rxstat.filthit, rxstat.rtr, rxstat.ext, rxstat.inv);
printf("\r\n DATA = ");
for (i=0;i<rx_len;i++) {
printf("%c ",in_data[i]);
}
printf("\r\n");
}
}
else {
printf("\r\nFAIL on GETD\r\n");
}
}
}
}
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Jun 05, 2007 11:08 pm |
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| Quote: |
char out_data;
i=can_putd(SEND_TO_PORT_B, out_data, tx_len,tx_pri,tx_ext,tx_rtr);
i=can_putd(SEND_TO_PORT_C, out_data, tx_len,tx_pri,tx_ext,tx_rtr);
|
The 2nd parameter in can_putd() is a pointer. Look at the source code
for can_putd() in this file: c:\program files\picc\drivers\can-18xxx8.c
Here's what it says:
| Quote: |
int1 can_putd(int32 id, int * data, int len, int priority, int1 ext, int1 rtr)
// Parameters:
// id - ID to transmit data as
// data - pointer to data to send
// len - length of data to send
// priority - priority of message. The higher the number, the
// sooner the CAN peripheral will send the message.
// Numbers 0 through 3 are valid.
// ext - TRUE to use an extended ID, FALSE if not
// rtr - TRUE to set the RTR (request) bit in the ID, false if NOT
//
// Returns:
// If successful, it will return TRUE
// If un-successful, will return FALSE
|
In addition to that, you're telling the driver that you have a buffer that
is 8 bytes in length, but your "buffer" is actually only one char:
| Quote: |
char out_data;
int1 tx_rtr=1;
int1 tx_ext=0;
int tx_len=8;
int tx_pri=3;
int i; |
Look at all the CCS examples for the CAN bus. Here are the filenames:
c:\program files\picc\examples\ex_can_ccs_b.c
c:\program files\picc\examples\ex_can.c
c:\program files\picc\examples\ex_can_ccs_a.c
Also, use the forum's search page to look for all threads that contain
either can_putd or can_getd. Study the examples. |
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