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khienpzo
Joined: 26 Nov 2012
Posts: 3
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| I2C 1 Master 2 Slave |
 Posted: Mon Nov 26, 2012 7:56 pm |
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Hi, I am doing one project communication 1 master and 2 slave i2c read data from ADC 2 slave master and sent to the computer. I refer to the code of "PCM programmer" but I have not read the ADC data.
Master code:
| Code: |
#include <16f877a.h>
#include <def_877a.h>
#device *=16 ADC=8
#FUSES NOWDT, HS, NOPUT, NOPROTECT, NODEBUG, NOBROWNOUT, NOLVP, NOCPD, NOWRT
#use delay(clock=4000000)
#use i2c(MASTER,SDA=PIN_C4,SCL=PIN_C3,fast)
#use RS232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8)
#define slave_address1 0x10
#define slave_address2 0x20
//========================
char data1,data2 =0;
unsigned int16 control;
//=========================
#INT_RDA
void ngatrs232()
{
char c;
c = getc();
if (c=='a')
{
putc(255);
putc(255);
delay_ms (10);
}
if (c== 'b' )
{
control = 1;
}
if (c== 'f' )
{
control = 2;
}
}
void main()
{
control=0;
data1 =0;
data2 =0;
enable_interrupts(INT_RDA);
ext_int_edge(H_TO_L);
enable_interrupts (GLOBAL);
delay_ms(50);
set_tris_D(0x00);
set_tris_C(0x80);
while(true)
{
i2c_start();
i2c_write(slave_address1);
data1 = i2c_read(0);
i2c_stop();
delay_ms(10);
i2c_start();
i2c_write(slave_address2);
data2 = i2c_read(0);
i2c_stop();
delay_ms(10);
if (control == 1)
{
putc(data1);
putc(data2);
delay_ms(10);
}
}
} |
code Slave 1
| Code: |
#include <16f877a.h>
#include <def_877a.h>
#device *=16 ADC=8
#FUSES NOWDT, HS, NOPUT, NOPROTECT, NODEBUG, NOBROWNOUT, NOLVP, NOCPD, NOWRT
#use delay(clock=4000000)
#use i2c (SLAVE,SDA=PIN_C4,SCL=PIN_C3,address=0x10,force_hw) // khai bao chuan truyen thong su dung//
//=====================================================
int8 adc_result;
#INT_SSP
void ssp_interrupt()
{
int8 incoming, state;
state = i2c_isr_state();
if(state < 0x80) // Master truyen du lieu
{
incoming = i2c_read();
}
if(state >= 0x80) // Master nhan du lieu tu Slave
{
i2c_write(adc_result);
}
}
//======================================
void main ()
{
setup_adc_ports(AN0);
setup_adc(ADC_CLOCK_DIV_8);
set_adc_channel(0);
delay_us(20);
adc_result = read_adc();
enable_interrupts(INT_SSP);
enable_interrupts(GLOBAL);
while(true)
{
adc_result = read_adc();
delay_ms(500);
}
} |
code Slave 2
| Code: |
#include <16f877a.h>
#include <def_877a.h>
#device *=16 ADC=8
#FUSES NOWDT, HS, NOPUT, NOPROTECT, NODEBUG, NOBROWNOUT, NOLVP, NOCPD, NOWRT
#use delay(clock=4000000)
#use i2c (SLAVE,SDA=PIN_C4,SCL=PIN_C3,address=0x20,force_hw) // khai bao chuan truyen thong su dung//
//=====================================================
int8 adc_result;
#INT_SSP
void ssp_interrupt()
{
int8 incoming, state;
state = i2c_isr_state();
if(state < 0x80) // Master truyen du lieu
{
incoming = i2c_read();
}
if(state >= 0x80) // Master nhan du lieu tu Slave
{
i2c_write(adc_result);
}
}
//======================================
void main ()
{
setup_adc_ports(AN0);
setup_adc(ADC_CLOCK_DIV_8);
set_adc_channel(0);
delay_us(20);
adc_result = read_adc();
enable_interrupts(INT_SSP);
enable_interrupts(GLOBAL);
while(true)
{
adc_result = read_adc();
delay_ms(500);
}
}
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Ttelmah
Joined: 11 Mar 2010
Posts: 19538
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| Posted: Tue Nov 27, 2012 12:40 am |
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You don't tell us what your problem actually is....
However killer code is doing two putc's and a delay in the INT_RDA. Multiple problems with this:
1) If data arrives while you are doing this, this _will_ hang the UART (add ERRORS to the RS232 declaration, and the compiler will add code to clear this).
2) Implies that all interrupts _will_ be disabled in the delays in the main....
Basically don't do this. If you must send from inside the interrupt, use a buffered TX. Or just use a flag and do the transmission in the external code. Never delay for more than a very few uSec in an ISR....
Other problem, is that you must read from the I2C, in state 0x80. Study the example code.
Best Wishes |
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Tue Nov 27, 2012 6:02 am |
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also ...
be sure to have the correct value resistors for the I2C bus lines.Usually 4k7 or 3k3 will work.
hth
jay |
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khienpzo
Joined: 26 Nov 2012
Posts: 3
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| reply I2C |
| Posted: Tue Nov 27, 2012 7:38 am |
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| I use resistor 2k2 for I2C line. |
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