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PICdawg
Joined: 13 Dec 2007
Posts: 17
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 Posted: Fri Dec 14, 2007 1:26 pm |
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Yes, I forgot that the s/w implementation is only for the master.
Also, I believe the problem in my implementation may be that my read did not specify the NAK parameter. After some review of the i2c spec, pic datasheet and the ccs manual, I think I understand why it should be there and when. I'll try that first!
Is it fair to say that if you are reading multiple data bytes, that your code needs to add the NAK parameter of 0 just to the last read call? I'm assuming this is how the master-receiver signals the slave that the read sequence is finished. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Dec 14, 2007 5:50 pm |
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| Quote: | | Is it fair to say that if you are reading multiple data bytes, that your code needs to add the NAK parameter of 0 just to the last read call? |
That's correct. |
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PICdawg
Joined: 13 Dec 2007
Posts: 17
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| Posted: Mon Dec 17, 2007 10:31 am |
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Thanks. I did add the NAK parameter to my master-receiver code and my demo program(s) came to life! My slave is running essentially the example slave program. Very simple master program.
I will try to use robotam's prgrams listed on the 1st page of this discussion and see if I can get to work in my proto environment using two 876a's. |
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robotam
Joined: 13 Nov 2007
Posts: 15
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| Posted: Mon Dec 17, 2007 10:36 am |
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| PICdawg wrote: | Thanks. I did add the NAK parameter to my master-receiver code and my demo program(s) came to life! My slave is running essentially the example slave program. Very simple master program.
I will try to use robotam's prgrams listed on the 1st page of this discussion and see if I can get to work in my proto environment using two 876a's. |
Hi PICdawg
can you please explain what did you change in your code? |
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PICdawg
Joined: 13 Dec 2007
Posts: 17
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| Posted: Mon Dec 17, 2007 7:51 pm |
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| See my private email to you. Rather than fill up this with the code I answered your question and sent you the code I used for my demo. |
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robotam
Joined: 13 Nov 2007
Posts: 15
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| Posted: Thu Dec 27, 2007 2:39 am |
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Hello,
I changed my dspic with a 18f as a slave and it works perfectly.i guess there is some modifications or configuration in the dspic. |
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hansimg
Joined: 24 May 2010
Posts: 8
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| Posted: Mon May 24, 2010 1:31 pm |
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Hey guys, I'm trying to communicate 2 pics 16f877, so I found this topic, and do exactly like you said. But it didn't work. When I try to simulate it in Proteus, the SCL line is kept in 0 and the program does nothing.
Here my master code:
| Code: |
#include <16F877.H>
#fuses XT, NOWDT, PROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
#use i2c(Master, sda=PIN_C4, scl=PIN_C3)
//====================================
void main()
{
int8 data;
// Write the letter 'B' to the slave board.
i2c_start();
i2c_write(0xA0);
i2c_write(0x00);
i2c_write('B');
i2c_stop();
// Read from the slave board and display the data.
i2c_start();
i2c_write(0xA0);
i2c_write(0x00);
i2c_start();
i2c_write(0xA1);
data = i2c_read(0);
i2c_stop();
printf("read %c \n\r", data);
while(1);
} |
And the slave code:
| Code: | ///////////////////////////////////////////////////////////////////////////
//// EX_SLAVE.C ////
//// ////
//// This program uses the PIC in I2C slave mode to emulate the ////
//// 24LC01 EEPROM. You can write to addresses 00h to 0Fh with it. ////
//// ////
//// This program is to be used in conjunction with the ex_extee.c ////
//// sample. Use the "#include <2402.C>" or "#include <2401.c>". ////
//// Only 16 bytes of address space are implemented, however. ////
//// ////
//// If using a compiler version before 2.639 add "*0x14 = 0x3E;" to ////
//// the begining of main(), and add "NOFORCE_SW" as the last ////
//// parameter in the #use i2c directive. ////
//// ////
//// Jumpers: ////
//// PCM,PCH pin C7 to RS232 RX, pin C6 to RS232 TX ////
//// ////
//// This example will work with the PCM and PCH compilers. The ////
//// following conditional compilation lines are used to include a ////
//// valid device for each compiler. Change the device, clock and ////
//// RS232 pins for your hardware if needed. ////
///////////////////////////////////////////////////////////////////////////
//// (C) Copyright 1996,2003 Custom Computer Services ////
//// This source code may only be used by licensed users of the CCS ////
//// C compiler. This source code may only be distributed to other ////
//// licensed users of the CCS C compiler. No other use, ////
//// reproduction or distribution is permitted without written ////
//// permission. Derivative programs created using this software ////
//// in object code form are not restricted in any way. ////
///////////////////////////////////////////////////////////////////////////
#if defined(__PCM__)
#include <16F877.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#elif defined(__PCH__)
#include <18F452.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#endif
#use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, address=0xa0)
BYTE address, buffer[0x10];
#INT_SSP
void ssp_interupt (){
BYTE incoming, state;
state = i2c_isr_state();
if(state <= 0x80) //Master is sending data
{
incoming = i2c_read();
if(state == 1) //First received byte is address
address = incoming;
if(state == 2) //Second received byte is data
buffer[address] = incoming;
}
if(state == 0x80) //Master is requesting data
{
i2c_write(buffer[address]);
}
}
void main ()
{
enable_interrupts(GLOBAL);
enable_interrupts(INT_SSP);
while (TRUE) {}
}
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Please, help.
Cya |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon May 24, 2010 1:42 pm |
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| Put 4.7K pull-up resistors on SCL and SDA. |
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hansimg
Joined: 24 May 2010
Posts: 8
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| Posted: Mon May 24, 2010 1:51 pm |
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| I already do it. =/ |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon May 24, 2010 2:07 pm |
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Post your Proteus schematic on a free image hosting website,
and then post a link to the image in this thread. |
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hansimg
Joined: 24 May 2010
Posts: 8
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| Posted: Mon May 24, 2010 2:17 pm |
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PCM_PROGRAMMER thanx for your attention, this is my schematic
 |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Mon May 24, 2010 2:40 pm |
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No clock source shown on either chip.
You are specifying 'XT', with a 4MHz delay, which implies an external 4MHz crystal for the master, and HS, and a 20MHz delay, which implies an external 20MHz crystal for the slave. Where are these?.
Best Wishes |
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hansimg
Joined: 24 May 2010
Posts: 8
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| Posted: Mon May 24, 2010 3:00 pm |
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I Change my schematic to this:
But it's still don't works... =/
X1 -> 4mhz and X2->20mhz |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon May 24, 2010 3:19 pm |
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It could be that Proteus doesn't correctly simulate a software i2c master.
Try adding FORCE_HW to the master:
| Quote: |
#use i2c(Master, sda=PIN_C4, scl=PIN_C3, FORCE_HW)
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The slave code doesn't need it. The slave always uses hardware i2c.
If that doesn't fix the problem, then it could be caused by your version
of Proteus. |
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hansimg
Joined: 24 May 2010
Posts: 8
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| Posted: Mon May 24, 2010 3:40 pm |
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I add force_hw to the master, then the problem was change, now the scl don't go to slow, and the program run until the end, but it's not writing on the slave and neither read.
I receive it on therminal:
"Read -1"
On debug "data" assumes 0xff value |
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