I2C Slave with a PIC

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  1. - 26th April 2012, 13:47 #1
    tacbanon's Avatar
    tacbanon
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    Default Please help me understand how the application works

    Hello,
    While waiting for my Pic16F88(probable by next week) I tried to play with this code below with success in the simulation...
    master(Pic18F2620)
    Code:
    DEFINE OSC 40


DEFINE I2C_HOLD 1


DEFINE LCD_DREG         PORTB          
DEFINE LCD_DBIT         0              
DEFINE LCD_RSREG        PORTB         
DEFINE LCD_RSBIT        4             
DEFINE LCD_EREG         PORTB          
DEFINE LCD_EBIT         5             
DEFINE LCD_BITS         4           
DEFINE LCD_LINES        2              
DEFINE LCD_COMMANDUS    2000         
DEFINE LCD_DATAUS       50           
PAUSE 100
LCDOUT $FE,1,$FE,2


ADCON1=001111
CMCON=000111


scl             VAR PORTC.3
sda             VAR PORTC.4                    


i2c_address     VAR BYTE


i2c_data        VAR BYTE[6]


main:


i2c_address=$02
I2CREAD sda,scl,i2c_address,[STR i2c_data\6]
LCDOUT $FE,$80,DEC i2c_data[0]
LCDOUT " ",    DEC i2c_data[1]
LCDOUT " ",    DEC i2c_data[2]
LCDOUT " ",    DEC i2c_data[3]
LCDOUT " ",    DEC i2c_data[4]
LCDOUT " ",    DEC i2c_data[5]


GOTO main
    Slave(Pic18F2620)
    Code:
    DEFINE OSC 40


INCLUDE "DT_INTS-18.bas"  
INCLUDE "ReEnterPBP-18.bas"


ADCON1=001111                            
CMCON=000111                      


i2c_buffer_full     VAR SSPSTAT.0 
i2c_read            VAR SSPSTAT.2
i2c_release_scl     VAR SSPCON1.4 


i2c_data            VAR BYTE[6]
i2c_data_index      VAR BYTE


dummy               VAR BYTE


;----------------------------------
i var byte
i=1


SSPADD=$02          ' I2C Address: $0A
SSPCON1=$36
SSPCON2.0=1


i2c_data[0]=6
i2c_data[1]=5
i2c_data[2]=4
i2c_data[3]=3
i2c_data[4]=2
i2c_data[5]=1




i2c_data_index=0


ASM
INT_LIST  macro  
        INT_Handler SSP_INT, _i2c_int_handler, PBP, yes
    endm
    INT_CREATE          
    INT_ENABLE SSP_INT
endasm




main:  


goto main 




i2c_int_handler:
IF i2c_read then
    dummy=SSPBUF
    IF i2c_buffer_full=0 THEN
        SSPBUF=i2c_data[i2c_data_index]
        i2c_data_index=i2c_data_index+1
        IF i2c_data_index=6 THEN i2c_data_index=0
    ENDIF
ENDIF
i2c_release_scl=1 
@ INT_RETURN
    As I understood, in the master pic the code below tries to communicate to the Slave having the address $02
    Code:
    i2c_address=$02
I2CREAD sda,scl,i2c_address,[STR i2c_data\6]
LCDOUT $FE,$80,DEC i2c_data[0]
LCDOUT " ",    DEC i2c_data[1]
LCDOUT " ",    DEC i2c_data[2]
LCDOUT " ",    DEC i2c_data[3]
LCDOUT " ",    DEC i2c_data[4]
LCDOUT " ",    DEC i2c_data[5]
    and display data from Slave to the Master pic LCD. Then I tried to modify the setup and add another Slave#2 with address $0B like the this code below..
    Code:
    main:


i2c_address=$02
I2CREAD sda,scl,i2c_address,[STR i2c_data\6]
LCDOUT $FE,$80,DEC i2c_data[0]
LCDOUT " ",    DEC i2c_data[1]
LCDOUT " ",    DEC i2c_data[2]
LCDOUT " ",    DEC i2c_data[3]
LCDOUT " ",    DEC i2c_data[4]
LCDOUT " ",    DEC i2c_data[5]


PAUSE 1000
LCDOUT 254,1
pause 500
i2c_address=$0B


I2CREAD sda,scl,i2c_address,[STR i2c_data\6]
LCDOUT $FE,$80,DEC i2c_data[0]
LCDOUT " ",    DEC i2c_data[1]
LCDOUT " ",    DEC i2c_data[2]
LCDOUT " ",    DEC i2c_data[3]
LCDOUT " ",    DEC i2c_data[4]
LCDOUT " ",    DEC i2c_data[5]


PAUSE 1000


GOTO main
    What I get is "6 5 4 3 2 1" and "0 0 0 0 0 0 " should be "1 2 3 4 5 6" for Slave#2
    Slave#2
    Code:
    DEFINE OSC 40


INCLUDE "DT_INTS-18.bas"  
INCLUDE "ReEnterPBP-18.bas"


ADCON1=001111                            
CMCON=000111                      


i2c_buffer_full     VAR SSPSTAT.0 
i2c_read            VAR SSPSTAT.2
i2c_release_scl     VAR SSPCON1.4 


i2c_data            VAR BYTE[6]
i2c_data_index      VAR BYTE


dummy               VAR BYTE


;----------------------------------
i var byte
i=1


SSPADD=$0B          ' I2C Address: $0B
SSPCON1=$36
SSPCON2.0=1


i2c_data[0]=1
i2c_data[1]=2
i2c_data[2]=3
i2c_data[3]=4
i2c_data[4]=5
i2c_data[5]=6




i2c_data_index=0


ASM
INT_LIST  macro  
        INT_Handler SSP_INT, _i2c_int_handler, PBP, yes
    endm
    INT_CREATE          
    INT_ENABLE SSP_INT
endasm




main:  


goto main 




i2c_int_handler:
IF i2c_read then
    dummy=SSPBUF
    IF i2c_buffer_full=0 THEN
        SSPBUF=i2c_data[i2c_data_index]
        i2c_data_index=i2c_data_index+1
        IF i2c_data_index=6 THEN i2c_data_index=0
    ENDIF
ENDIF
i2c_release_scl=1 
@ INT_RETURN
    I was only hoping that it would work that way(I guess not ), how can I add another Slave and get data from it? I appreciate any help and the time for sharing.

    Thanks in advance,
    tacbanon
    Name: I2cerr1234.gif Views: 3167 Size: 120.2 KB
    Last edited by tacbanon; - 26th April 2012 at 13:56.
  2. - 26th April 2012, 17:24 #2
    Darrel Taylor's Avatar
    Darrel Taylor
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    Default Re: Please help me understand how the application works

    In your previous code with the F88, 3 is not a valid I2C address.
    In the current code, $B is not a valid I2C address.

    They should be a multiple of 2.
    Bit 0 is reserved for the R/W bit.
    DT
  3. - 27th April 2012, 12:48 #3
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    Default Re: Please help me understand how the application works

    Quote Originally Posted by Darrel Taylor View Post
    In your previous code with the F88, 3 is not a valid I2C address.
    In the current code, $B is not a valid I2C address.

    They should be a multiple of 2.
    Bit 0 is reserved for the R/W bit.
    Hi Darrel,
    Thanks for replying, I did some testing on 1Master and 1Slave with these address($02,$04,$06,$08,$10,$12,$14) and works fine. But when I trying to add Slave #2 I get "0 0 0 0 0 0". It only reads on the Slave #1 correct (displays "1 2 3 4 5 6").
    This is how I code to read the 2nd Slave.
    Code:
    DEFINE OSC 40


DEFINE I2C_HOLD 1


DEFINE LCD_DREG         PORTB          
DEFINE LCD_DBIT         0              
DEFINE LCD_RSREG        PORTB         
DEFINE LCD_RSBIT        4             
DEFINE LCD_EREG         PORTB          
DEFINE LCD_EBIT         5             
DEFINE LCD_BITS         4           
DEFINE LCD_LINES        2              
DEFINE LCD_COMMANDUS    2000         
DEFINE LCD_DATAUS       50           
PAUSE 100
LCDOUT $FE,1,$FE,2


ADCON1=001111
CMCON=000111


scl             VAR PORTC.3
sda             VAR PORTC.4                    


i2c_address     VAR BYTE
i2c_address2     VAR BYTE


i2c_data        VAR BYTE[6]
i2c_data2       VAR BYTE[6] 




main:


i2c_address=$10
pause 200
I2CREAD sda,scl,i2c_address,[STR i2c_data\6]
LCDOUT $FE,$80,"1> ",DEC i2c_data[0]
LCDOUT " ",    DEC i2c_data[1]
LCDOUT " ",    DEC i2c_data[2]
LCDOUT " ",    DEC i2c_data[3]
LCDOUT " ",    DEC i2c_data[4]
LCDOUT " ",    DEC i2c_data[5]


PAUSE 500
LCDOUT $FE,1
'*********************************************
i2c_address2=$14
pause 200
I2CREAD sda,scl,i2c_address2,[STR i2c_data2\6]
LCDOUT $FE,$80,"2> ",DEC i2c_data2[0]
LCDOUT " ",    DEC i2c_data2[1]
LCDOUT " ",    DEC i2c_data2[2]
LCDOUT " ",    DEC i2c_data2[3]
LCDOUT " ",    DEC i2c_data2[4]
LCDOUT " ",    DEC i2c_data2[5]


PAUSE 500
LCDOUT $FE,1  
GOTO main
    BTW the code for Slave1 and Slave2 are identical (Slave#1 is address $10 and Slave#2 is address $14)
    What I'm doing wrong in the code? I appreciate very much your help.

    Thanks,
    Tacbanon
    Last edited by tacbanon; - 27th April 2012 at 12:53.
  4. - 27th April 2012, 17:35 #4
    Darrel Taylor's Avatar
    Darrel Taylor
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    Default Re: Please help me understand how the application works

    If you comment out the first I2CREAD, is it able to read from the second slave?

    If you change the order so that it reads the second slave first, is it then unable to read the first slave?
    DT
  5. - 27th April 2012, 17:52 #5
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    tacbanon
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    Default Re: Please help me understand how the application works

    If you comment out the first I2CREAD, is it able to read from the second slave?
    Yes it is able to read.
    If you change the order so that it reads the second slave first, is it then unable to read the first slave?
    Nope, displays "0 0 0 0 0 0" for first Slave, 2nd Slave shows "6 5 4 3 2 1"
    Last edited by tacbanon; - 27th April 2012 at 17:57.
  6. - 27th April 2012, 19:17 #6
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    Default Re: Please help me understand how the application works

    It sounds like a buffer overflow.

    ... bad comment deleted ... duh!!

    If you post or email your .DSN, I'll take a closer look.
    Last edited by Darrel Taylor; - 28th April 2012 at 03:20.
    DT
  7. - 28th April 2012, 00:34 #7
    tacbanon's Avatar
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    Default Re: Please help me understand how the application works

    Thanks Darrel, oh sorry to ask this, but how do I send a winrar file?
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