I2C Slave with a PIC

**tacbanon** · - 25th April 2012, 09:59

Hi again,
Here is the code I'm using..
Master pic using Pic16F877A

Code:

'-------------------------------------------------------------------------------
' Master
'-------------------------------------------------------------------------------
'-------------------------------------------------------------------------------


DEFINE OSC 4


'OPTION_REG.7 = 0


ADCON1 = 7


'------------------------------------------------------------------------------


DEFINE I2C_SLOW 1


TRISB.5 = 1
TRISB.7 = 1


'------------------------------------------------------------------------------


scl VAR PORTB.5        ' i2c clock input
sda VAR PORTB.7     ' i2c data input


'------------------------------------------------------------------------------


I2Caddress VAR BYTE


valor VAR BYTE


'------------------------------------------------------------------------------


' Set LCD Data port
DEFINE LCD_DREG PORTD
' Set starting Data BIT (0 OR 4) IF 4-BIT bus
DEFINE LCD_DBIT 4
' Set LCD Register Select port
DEFINE LCD_RSREG PORTC
' Set LCD Register Select BIT
DEFINE LCD_RSBIT 6
' Set LCD Enable port
DEFINE LCD_EREG PORTC
' Set LCD Enable BIT
DEFINE LCD_EBIT 7
' Set LCD bus size (4 OR 8 bits)
DEFINE LCD_BITS 4
' Set number of lines ON LCD
DEFINE LCD_LINES 2
' Set command delay time in us
DEFINE LCD_COMMANDUS 2000
' Set Data delay time in us
DEFINE LCD_DATAUS 50


'------------------------------------------------------------------------------


Pause 500       ' Wait for LCD to startup
LCDOut $fe, 1
LCDOut $fe, "Daniel"
Pause 500       ' Wait for LCD to startup


valor = 0


'------------------------------------------------------------------------------


main:
      I2Caddress = $3


      LCDOut $fe, 1
      LCDOut "Write 1 - LED ON"
      Pause 500


      I2CWrite SDA, SCL, I2Caddress, [6], bogus ' Write offset to slave
      Pause 500


      LCDOut $fe, 1
      LCDOut "Write 1 - LED OFF"
      Pause 500


      I2CWrite SDA, SCL, I2Caddress, [8], bogus ' Write to slave
      Pause 500


      LCDOut $fe, 1
      LCDOut "Reading 1..."
      Pause 500


      I2CRead SDA, SCL, I2Caddress, [valor], bogus ' Read from slave
      LCDOut $fe, 1
      LCDOut "Value1: ", DEC valor
      Pause 500


      '--------


      I2Caddress = $5


      LCDOut $fe, 1
      LCDOut "Write 2 - LED ON"
      Pause 500


      I2CWrite SDA, SCL, I2Caddress, [4], bogus ' Write to slave
      Pause 500


      LCDOut $fe, 1
      LCDOut "Write 2 - LED OFF"
      Pause 500


      I2CWrite SDA, SCL, I2Caddress, [10], bogus ' Write to slave
      Pause 500


      LCDOut $fe, 1
      LCDOut "Reading 2..."
      Pause 500


      I2CRead SDA, SCL, I2Caddress, [valor], bogus ' Read from slave
      LCDOut $fe, 1
      LCDOut "Value2: ", DEC valor
      Pause 500


      '--------


      GoTo main       ' Do it forever


'-------------------------------------------------------------------------------


bogus:
        LCDOut $fe,1, "Time out"    ' I2C command timed out
        Pause 500


        GoTo main


'-------------------------------------------------------------------------------


End

Here is the code for the Slave Pic16F88

Code:

DEFINE OSC 8
OSCCON = 110001 '8mhz


'------------------------------------------------------------------------------


CMCON = 7
ADCON1 = 0 ' Disable A/D converter
ADCON0 = 0
ANSEL = 0 ' all analog pins to digital


'--- tris port config here (don't use SCL & SDA pins other than I2C) ----------


DEFINE I2C_HOLD 1


TRISB.1 = 1
TRISB.4 = 1

'--- Alias pins ---------------------------------------------------------------


SDADIR VAR TRISB.1
SCLDIR VAR TRISB.4


'--- Define here your variables and alias -------------------------------------


LEDT VAR PORTA.2
LEDL VAR PORTB.7
LEDM VAR PORTB.6
LEDR VAR PORTB.5
readcnt VAR BYTE
datain VAR BYTE
WrData VAR BYTE


'--- Define used register flags ------------------------------------------------


SSPIF               VAR PIR1.3    ' SSP (I2C) interrupt flag
SSPIE               VAR PIE1.3 
BF                  VAR SSPSTAT.0 ' SSP (I2C) Buffer Full
R_W                 VAR SSPSTAT.2 ' SSP (I2C) Read/Write
D_A                 VAR SSPSTAT.5 ' SSP (I2C) Data/Address
CKP                 VAR SSPCON.4  ' SSP (I2C) SCK Release Control
SSPEN               VAR SSPCON.5  ' SSP (I2C) Enable
SSPOV               VAR SSPCON.6  ' SSP (I2C) Receive Overflow Indicator
WCOL                VAR SSPCON.7  ' SSP (I2C) Write Collision Detect
STAT_BF             VAR SSPSTAT.0 ' SSP (I2C) Buffer Full
STAT_RW             VAR SSPSTAT.2 ' SSP (I2C) Read/Write
STAT_DA             VAR SSPSTAT.5 ' SSP (I2C) Data/Address
CKE                 VAR SSPSTAT.6 ' SSP (I2C) Data/Address


'--- Rx Buffer defintion ------------------------------------------------------


RxBufferLEN         CON 1       
RxBuffer            VAR BYTE[Rxbufferlen]
RxBufferIndex       VAR BYTE


'--- Tx Buffer defintion ------------------------------------------------------


TxBufferLEN         CON 1
TxBuffer            VAR BYTE[txbufferlen]
TxBufferIndex       VAR BYTE


'--- Define constants ---------------------------------------------------------


I2Caddress          CON $3 ' Make address = 3


'--- Initialize I2C slave mode ------------------------------------------------


SCLDIR = 1          ' SCL must be an input before enabling interrupts
SDADIR = 1   
SSPADD = I2Caddress ' Set our address
SSPCON = $36        ' Set to I2C slave with 7-bit address
SSPSTAT = 0
SSPIE = 1 
SSPIF = 0 
RxBufferIndex = 0
TxBufferIndex = 0


'--- Initialization Done! -----------------------------------------------------


GoTo main


'--- I2C subroutine  ----------------------------------------------------------


i2cslave:                                      ' I2C slave subroutine
          SSPIF = 0                            ' Clear interrupt flag
          IF R_W = 1 Then i2crd                ' Read data from us
          IF BF = 0 Then i2cexit               ' Nothing in buffer so exit
          IF D_A = 1 Then i2cwr                ' Data for us (not address)
          IF SSPBUF != I2Caddress Then i2cexit ' Clear the address from the buffer
          readcnt = 0                          ' Mark as first read
          GoTo i2cexit


i2cwr:                                ' I2C write data to us
       datain = SSPBUF                ' Put buffer data into array
       Rxbuffer[Rxbufferindex]=datain
       Rxbufferindex=rxbufferindex+1


       IF rxbufferindex=RxBufferLEN Then           ' end of buffer transfer 
          WrData=1
          rxbufferindex=0
       EndIF


       GoTo i2cexit


i2crd:                                      ' I2C read data from us
       IF D_A = 0 Then
          TxBufferIndex = 0
       EndIF


       While STAT_BF : Wend                        ' loop while buffer is full


       wcol = 0                                    ' clear collision flag
       SSPBUF = TxBuffer[TxBufferIndex]


       While wcol 
             wcol = 0
             SSPBUF = TxBuffer[TxBufferIndex]
       Wend


       CKP = 1                                     ' release clock, allowing read by master
       TxBufferIndex = TxBufferIndex + 1           ' increment index
       IF TxBufferIndex = TxBufferlen Then         ' all bytes have been tx
          TxBufferIndex = 0                           ' reset index            
       EndIF
             
i2cexit:
         Return


'--- End I2C subroutine  ------------------------------------------------------


Main:
     
      pause 100
      txbuffer = 12


      IF SSPIF = 1 Then
         GoSub i2cslave
      EndIF


      SSPOV = 0
      WCOL = 0


      Select Case RxBuffer[0]
             Case 6
                     High LEDT
             Case 8
                     Low LEDT
      End Select


      WrData=0  
      GoTo Main


'------------------------------------------------------------------------------


End

The codes I'm using is from Daniel(copy and paste).
BTW I'm using a simulator...

regards,
tacbanon

**aratti** · - 25th April 2012, 15:18

Very likely is a simulator problem!

Al.

**tacbanon** · - 25th April 2012, 16:15

Okay, I will try it in the real hardware(need first to buy Pic16F88), and post here the result. Can anybody in the forum who has Proteus to try to test if similar output I'm having?

Thanks,
tacbanon

**tacbanon** · - 26th April 2012, 12:47

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
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Name: I2cerr1234.gif
Views: 3041
Size: 120.2 KB

**Darrel Taylor** · - 26th April 2012, 16:24

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.

**tacbanon** · - 27th April 2012, 11:48

Originally Posted by Darrel Taylor

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

**Darrel Taylor** · - 27th April 2012, 16:35

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?

**Address** · - 19th August 2016, 06:47

I need Working I2C Slave code for PIC16LF1513 in C program with some instructions.

**Scampy** · - 21st August 2016, 17:44

Originally Posted by Address

I need Working I2C Slave code for PIC16LF1513 in C program with some instructions.

So why post on a BASIC forum -

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