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stoyanoff
Joined: 20 Jul 2011
Posts: 375
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| Problem with RS485 |
 Posted: Mon May 19, 2014 5:57 am |
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Greatings! I`m trying to connect 2 PIC18F2550 through RS485. I`m using sn75176b as RS485 transceiver. So I`ve connected PIN_C7 to pin1 of the sn75176b(R).
PIN_C6 - > pin 4(D)
PIN_b0 -> pin 2 (RE)
PIN_B1 -> pin 3 (DE)
I have 10k resistor between every pin and Vcc. The problem is I can`t pass the rs485_init(); procedure. The program stops on this row :
#use rs232(baud=9600, xmit=RS485_TX_PIN, rcv=RS485_RX_PIN, enable=RS485_ENABLE_PIN, bits=9, long_data, errors, stream=RS485)
I`ve removed the multimaster directive from the down row because the compiler doesn`t liked it.
Can you tell where to look for the problem?!
Thanks!
PP: The controller is working. I`ve made a blink test and the frequency is correct! |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Mon May 19, 2014 6:17 am |
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| got code and compiler version ? |
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stoyanoff
Joined: 20 Jul 2011
Posts: 375
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| Posted: Mon May 19, 2014 7:32 am |
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Compiler version 4.134, MPLab 8.91.
Here is my master code:
| Code: |
#include <18F2550.h>
#device *=16
#fuses NOWDT,CPUDIV1
#use delay(clock=7372862)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, stream=PC)
#define RS485_RX_BUFFER_SIZE 64
#define RS485_USE_EXT_INT TRUE
int8 OUR_RS485_ID = 0;
#define RS485_ID OUR_RS485_ID
#include <rs485.c>
#include <stdlib.h>
int8 in_char = 0;
#INT_RDA
void serial_isr()
{
in_char = fgetc(PC);
}
void main()
{
rs485_init();
while(1)
{
delay_ms(10);
}
}
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The program never reaches the main loop(delay_ms(10)). It stops o this row
#use rs232(baud=9600, xmit=RS485_TX_PIN, rcv=RS485_RX_PIN, enable=RS485_ENABLE_PIN, bits=9, long_data, errors, stream=RS485)
It seems it can`t define the uart. I don`t know why...
Do you need anything else? I can post the settings in the RS485 file, but I don`t think I`ve made a mistake there. I just changed the pins!
Thanks! |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19589
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| Posted: Mon May 19, 2014 7:59 am |
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The setting:
#define RS485_USE_EXT_INT TRUE
Means that the RS485 RX pin _must_ connect to the INT_EXT pin, but you show this pin as being used for receive enable.....
Read the comments inside the RS485.c file |
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