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kitty
Guest
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| is my RS485 connection wrong? |
 Posted: Sat Feb 25, 2006 7:52 pm |
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I am using MPLAP IDE v6.60, 18F458, and try to using testing code to try rs485 connection between 2 PIC that is master and slave with MAX485.
my connection pin as below:-
PIN_C7 to RO
PIN_C6 to DI
PIN_B4 to DE
PIN_B5 to RE
ground to pin 5
+5 to pin Vcc
pin A of max485(master) to pin A of max485(slave)
pin B of max485(master) to pin B of max485(slave)
after compile and write to PICs, nothing show at LCD.
Why?
| Code: |
//master
#include<18f458.h>
#fuses HS, NOWDT, NOLVP, NOBROWNOUT, NOPROTECT, PUT
#use delay(clock = 20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, enable=PIN_B4, stream=RS485)
#define RS485_ID 0x10 // The device's RS485 master address
#define RS485_USE_EXT_INT TRUE // Select asynchronous serial interrupt
#include<RS485.c>
#include <lcd.c>
int buffer[40];
int next_in = 0;
int next_out = 0;
#INT_RDA
void serial_isr()
{
int t;
buffer[next_in] = fgetc(RS485);
t = next_in;
next_in = (next_in+1) % sizeof(buffer);
if(next_in == next_out)
next_in=t; // Buffer full !!
}
void main(void)
{
int j;
int data_received[32];
lcd_init();
// lcd_putc("\fSystem ready.\n");
enable_interrupts(INT_RDA);
enable_interrupts(GLOBAL);
rs485_init();
while(1)
{
rs485_wait_for_bus(FALSE);
//send address=0x11, length = 1, msg=3
if(rs485_send_message(0x11, 1, 3))
{
printf("\ftest 1");
delay_ms(100);
}
delay_ms(5);
if(rs485_get_message(data_received, FALSE))
{
for(j=0; j<3; ++j)
data_received[j] = buffer[j];
if(data_received[2]==6)
//if slave receives the number 3 successfully
{ //slave will send back number 6
printf(lcd_putc, "\ftest");
delay_ms(100);
}
}
}
}
//slave
#include<18f458.h>
#fuses HS, NOWDT, NOLVP, NOBROWNOUT, NOPROTECT, PUT
#use delay(clock = 20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, enable=PIN_B4, stream=RS485)
#define RS485_ID 0x11 // The device's RS485 slave address or ID
#define RS485_USE_EXT_INT TRUE // Select asynchronous serial interrupt
#include<RS485.c>
#include <lcd.c>
int buffer[40];
int next_in = 0;
int next_out = 0;
#INT_RDA
void serial_isr()
{
int t;
buffer[next_in] = fgetc(RS485);
t = next_in;
next_in = (next_in+1) % sizeof(buffer);
if(next_in == next_out)
next_in=t; // Buffer full !!
}
void main(void)
{
int j;
int data_received[32];
lcd_init();
enable_interrupts(INT_RDA);
enable_interrupts(GLOBAL);
rs485_init();
lcd_putc("\fSstem ready.\n");
while(1)
{
if(rs485_get_message(data_received, TRUE))
{
for(j=0; j<3; ++j)
data_received[j] = buffer[j];
if(data_received[0] == 0x11)
{
printf("\ftest");
delay_ms(100);
rs485_wait_for_bus(FALSE);
//after receive successfully, respond to master by sending number 6
if(rs485_send_message(0x10, 1, 6))
{
printf("\ftest");
delay_ms(100);
}
}
}
}
}
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Humberto
Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata
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| Posted: Sat Feb 25, 2006 10:19 pm |
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| Quote: |
#define RS485_USE_EXT_INT TRUE // Select asynchronous serial interrupt
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This directive should be used if you want to use the EXTERNAL INTERRUPT PIN as software UART receiver.
This directive also override the pins selected in the previous #use rs232(.....) directive.
But your intention is to use the built-in hardware UART because you selected the dedicated UART pins:(in bold)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, enable=PIN_B4, stream=RS485)
Hence you need to use this directive, (or not use at all) because you DO NOT want to use the
EXTERNAL INTERRUPT PIN as UART receiver.
#define RS485_USE_EXT_INT FALSE // Select asynchronous serial
| Quote: |
PIN_C7 to RO
PIN_C6 to DI
PIN_B4 to DE
PIN_B5 to RE
ground to pin 5
+5 to pin Vcc
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This is OK but DE and RE must be tied together or keep RE low.
Humberto |
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kitty
Guest
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| rs485 |
| Posted: Sun Feb 26, 2006 9:54 pm |
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Thanks, humberto.
I change my code as you told :
| Code: |
//master
#include<18f458.h>
#fuses HS, NOWDT, NOLVP, NOBROWNOUT, NOPROTECT, PUT
#use delay(clock = 20000000)
#define RS485_ID 0x10 // The device's RS485 master address
#define RS485_USE_EXT_INT FALSE
#include<RS485.c>
#include <lcd.c>
int buffer[40];
int next_in = 0;
int next_out = 0;
//#INT_RDA
void serial_isr()
{
int t;
buffer[next_in] = fgetc(RS485);
t = next_in;
next_in = (next_in+1) % sizeof(buffer);
if(next_in == next_out)
next_in=t; // Buffer full !!
}
void main(void)
{
int j;
int data_received[32];
lcd_init();
// enable_interrupts(INT_RDA);
// enable_interrupts(GLOBAL);
rs485_init();
while(1)
{
rs485_wait_for_bus(FALSE);
if(rs485_send_message(0x11, 1, 3))
{
lcd_putc("\fsend 1");
delay_ms(100);
}
delay_ms(5);
}
}
//slave
#include<18f458.h>
#fuses HS, NOWDT, NOLVP, NOBROWNOUT, NOPROTECT, PUT
#use delay(clock = 20000000)
//#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, enable=PIN_B4, stream=RS485)
#define RS485_ID 0x11 // The device's RS485 slave address or ID
#define RS485_USE_EXT_INT FALSE // Select asynchronous serial interrupt
#include<RS485.c>
#include <lcd.c>
int buffer[40];
int next_in = 0;
int next_out = 0;
//#INT_RDA
void serial_isr()
{
int t;
buffer[next_in] = fgetc(RS485);
t = next_in;
next_in = (next_in+1) % sizeof(buffer);
if(next_in == next_out)
next_in=t; // Buffer full !!
}
void main(void)
{
int j;
int data_received[32];
lcd_init();
// enable_interrupts(INT_RDA);
// enable_interrupts(GLOBAL);
rs485_init();
while(1)
{
if(rs485_get_message(data_received, TRUE))
{
data_received[0] = buffer[0];
data_received[1] = buffer[1];
data_received[2] = buffer[2];
data_received[3] = buffer[3];
printf(lcd_putc,"\f%d %d %d %d",data_received[0],data_received[1],data_received[2],data_received[3]);
}
}
}
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When those PICs run, master keep on sending to slave. But I am trying to retrive data at slave PIC using data_receive[0] to [3], I think this is not the right way because non of them show number 3 that send from master.
Very sorry, I try to read all post from search rs485 but I can solve it.
Please 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: Mon Feb 27, 2006 6:20 am |
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The system is behaving according to the code that has written.
1) I don't see any code in your Slave that will send back data to the Master.
2) I don't see any code in your Master to show the retrieved string, something like this:
if(rs485_get_message(data_received, FALSE))
Does your Slave is receiving the data packet ?
Humberto |
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kitty
Guest
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| Posted: Mon Feb 27, 2006 11:02 pm |
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Hi, thank for reply.
In fact my master can send data because I connected one led at TX line and It blink when sending data.
I only sending data number 0 to 15 from master to slave.
| Code: |
//master pic
while(1)
{
rs485_wait_for_bus(FALSE);
if(rs485_send_message(0x11, 20, j))
{
printf(lcd_putc,"\fsend %d",j);
delay_ms(100);
}
delay_ms(1000);
if(j<15)j++;
else j=0;
}
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but I do not know the right way to reveice data at slave site. I try the code as below
| Code: |
//slave pic
while(1)
{
if(rs485_get_message(data_received,FALSE)){
for(j=0;j<data_received[1];++j)
fputc(data_received[j+2],RS485);
l=data_received;
printf(lcd_putc,"\f%d %d %d ",data_received[0],
data_received[1],data_received[2]);
}
}
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lcd at slave pin doesnt get the right massage from master.
I do not know what to do now? |
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