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neverlog
Joined: 02 May 2010
Posts: 36
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 Posted: Thu Aug 12, 2010 9:29 pm |
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Dear All,
in the ex_PBUSM.c example, in line 71.
#bit intf=11.1
May I know what is this line means?
Thank you very much on your help.
I really appreciate the help. Thanks!! |
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Humberto
Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata
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| Posted: Fri Aug 13, 2010 7:48 am |
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Well, I'm agree with you that some examples there are not so good documented as one expect and some
lines of code is hidden behind an abstraction, like: #bit intf=11.1
If you look at in the Microchip MCU datasheets, you will note that intf is the name of bit 1 of the INTCON
Register, this apply to all midrange MCUs, where the Registers names and its bits Position names, are the same.
See the PIC16F877 datasheet, P.15
TABLE 2-1: SPECIAL FUNCTION REGISTER SUMMARY On Bank0, at the address 0x0B you will see the
INTCON Reg, hence: #bit intf=11.1 // has the same meaning in decimal notation.
Regarding your previous question:
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Does anyone know what is PBUS_NEED_CS=0x84 using for?
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It is also undocumented info, it is an implementation of One-wire communication.
The example use some concepts from LIN protocol, that is an open collector driver line and, being a
Master/Slave protocol, both handle the transfer of information, hence it is necesary a tight protocol in order
to arbitrate how to handle an unique communication line. In the LIN protocol there are defined only one
command: SLEEP (command code 0x80) and CCS use the command line PBUS_IDLE=0x80 with the same efect.
The LIN Protocol Specification does not define the content of each message (except for the SLEEP),
hence command like PBUS_NEED_LEN=0x81,PBUS_NEED_TO=0x82, PBUS_NEED_FROM=0x83,
PBUS_NEED_CS=0x84 can be freely created/used according with the applications needs.
All the previous comments regarding ex_pbus.c and the relation with LIN are my own conclusion, I would
appreciate corrections from somebody that had been putting your hand in this stuff and/or have a better
info to share, will be welcome to enrich the forum.
Humberto |
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neverlog
Joined: 02 May 2010
Posts: 36
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| Posted: Mon Aug 16, 2010 8:57 am |
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Thank you Humberto for your kind sharing.
It helps me look into this matter from different perspective. Thanks! |
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neverlog
Joined: 02 May 2010
Posts: 36
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| Posted: Thu Aug 19, 2010 3:08 am |
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Dear All,
I have study the whole code for ex_PBUSM.c
I have modify the program, but the master just won't receive the data send by slave. My compiler is 4.104. I have debugged for 2 days. I just can't figure why. Anyone please help me! I am going nuts....
Slave code(Transmitting data)
| Code: |
#include <18F4520.h>
#fuses hs,noprotect,nowdt,nolvp,BROWNOUT
#use delay(clock=20000000) //40mhz
#use rs232(baud=9600, float_high, bits=9, xmit=PIN_B2, rcv=PIN_B2)
//For Multiple MCU Communication=================================
#define OUR_ID 1
#byte porta=5
#byte portb=6
#byte portc=7
#define MAX_LENGTH 7
byte pbus_buffer[MAX_LENGTH+1];
byte start_receive=0;
enum pbus_states {PBUS_IDLE=0x80,PBUS_NEED_LEN=0x81,PBUS_NEED_TO=0x82,
PBUS_NEED_FROM=0x83,PBUS_NEED_CS=0x84};
byte pbus_state=PBUS_IDLE;
byte checksum;
byte last_byte;
#bit ninth_bit = RS232_ERRORS.7
#bit collision = RS232_ERRORS.6
#bit intf = 11.1
//Communication Line for Multi-MCU using B2 interrupts=========================
void pbus_send( byte * message, byte to, byte len) {
byte checksum,i;
retry:
checksum=len^OUR_ID^to;
disable_interrupts(GLOBAL);
collision=false;
ninth_bit=1;
putc(0xf1); if(collision) goto error;
putc(to); if(collision) goto error;
putc(OUR_ID); if(collision) goto error;
putc(len); if(collision) goto error;
ninth_bit=0;
for(i=1;i<=len;++i) {
checksum^=*message;
putc(*(message++)); if(collision) goto error;
}
putc(checksum); if(collision) goto error;
intf=false;
enable_interrupts(GLOBAL);
return;
error:
delay_ms(16);
enable_interrupts(GLOBAL);
goto retry;
}
//main program================================================
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#include <input.c>
void main() {
byte mychar,yto,ylen,y,msg[MAX_LENGTH];
delay_ms(1000);
ext_int_edge( h_to_l );
enable_interrupts(global);
enable_interrupts(int_ext2); //enable interrupts on B2
do {
output_high(PIN_B7);
mychar=pbus_buffer[2];
msg[0]=0x41;
msg[1]=0x42;
msg[3]=0x43;
msg[4]=0x44;
msg[5]=0x45;
msg[6]=0x46;
//msg[7]=0x50;
//msg[8]=0x48;
yto=0x39; //9 , Master ID
ylen=0x38; //8
pbus_send(msg,yto,ylen); //master ID is 16, len is 80
delay_ms(1000);
output_low(pin_B7);
delay_ms(1000);
} while(true);
}
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Master Code(Receiving Data)
| Code: |
#include <18F4520.h>
#fuses hs,noprotect,nowdt,nolvp,BROWNOUT
#use delay(clock=20000000) //40mhz
#use rs232(baud=9600, float_high, bits=9, xmit=PIN_B2, rcv=PIN_B2)
//For Multiple MCU Communication=================================
#define OUR_ID 9 //master id =16
#define MAX_LENGTH 95
byte pbus_buffer[MAX_LENGTH+1];
byte start_receive=false;
enum pbus_states {PBUS_IDLE=0x80,PBUS_NEED_LEN=0x81,PBUS_NEED_TO=0x82,
PBUS_NEED_FROM=0x83,PBUS_NEED_CS=0x84};
byte pbus_state=PBUS_IDLE;
byte checksum;
byte last_byte;
#bit ninth_bit = RS232_ERRORS.7
#bit collision = RS232_ERRORS.6
#bit intf = 11.1
#byte porta=5
#byte portb=6
#byte portc=7
//Communication Line for Multi-MCU using B2 interrupts=========================
#int_ext2
void pbus_isr() {
byte data;
if(kbhit()) {
data=getc();
if(ninth_bit) {
switch(pbus_state) {
case PBUS_IDLE : if(data==0xf1)
pbus_state=PBUS_NEED_TO;
break;
case PBUS_NEED_TO :
if(data==OUR_ID)
pbus_state=PBUS_NEED_FROM;
else
pbus_state=PBUS_IDLE;
checksum=data;
break;
case PBUS_NEED_FROM :
pbus_buffer[0] = data;
pbus_state=PBUS_NEED_LEN;
checksum^=data;
break;
case PBUS_NEED_LEN :
last_byte = data+1;
pbus_buffer[1] = data;
pbus_state=2;
checksum^=data;
break;
}
} else{
if(pbus_state==PBUS_NEED_CS) {
if(checksum==data)
start_receive=true; //next_in = (next_in+1) % MAX_MESSAGES;
else start_receive=false;
pbus_state=PBUS_IDLE;
} else if(pbus_state<0x80) {
pbus_buffer[pbus_state] = data;
checksum^=data;
if(++pbus_state>last_byte)
pbus_state=PBUS_NEED_CS;
}
}
}
}
//main program================================================
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#include <input.c>
void main() {
byte to,len,i,msg[MAX_LENGTH];
ext_int_edge( h_to_l );
enable_interrupts(global);
enable_interrupts(int_ext2); //enable interrupts on B2
set_tris_b(0b00000001);
output_low(pin_B6);
output_low(pin_B7);
delay_ms(500);
printf("\r\n\Multi MCU-Master Controller V1.0\r\n");
printf("\r\nReceive Mode ready\r\n");
do {
if(start_receive) { //if checksum ok, then start print data
//delay_ms(50);
printf("\r\nData ID from #%d: ",pbus_buffer[0]);
for(i=2;i<=10;++i){
printf(" %2X",pbus_buffer[i]);
}
start_receive=false;
}
} while(true);
}
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Please help me! Thanks in advance! Thank you. |
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neverlog
Joined: 02 May 2010
Posts: 36
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| Posted: Thu Aug 19, 2010 5:15 am |
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I have corrected some bug.
ext_int_edge( 2, h_to_l );
enable_interrupts(int_ext2);
But still can't work.... Please help! |
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