Problem with I2C

[Darrel Taylor]

I got a good laugh out of this one.
When the code doesn't work, rewrite PBP's I2C commands ...

Try this ...

DEFINE OSC 48
CLEAR

#config
    __CONFIG    _CONFIG1L, _PLLDIV_5_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L
    __CONFIG    _CONFIG1H, _FOSC_HSPLL_HS_1H & _FCMEN_OFF_1H & _IESO_OFF_1H
    __CONFIG    _CONFIG2L, _PWRT_OFF_2L & _BOR_ON_2L & _BORV_3_2L & _VREGEN_ON_2L
    __CONFIG    _CONFIG2H, _WDT_ON_2H & _WDTPS_512_2H
    __CONFIG    _CONFIG3H, _CCP2MX_ON_3H & _PBADEN_OFF_3H & _LPT1OSC_OFF_3H & _MCLRE_OFF_3H
    __CONFIG    _CONFIG4L, _STVREN_ON_4L & _LVP_OFF_4L & _XINST_OFF_4L
#endconfig

;----[LCD definitions]--------------------------------------------------------
DEFINE LCD_DREG  PORTB                            ; LCD Data port
DEFINE LCD_DBIT  4                                ; starting Data bit (0 or 4)
DEFINE LCD_EREG  PORTB                            ; LCD Enable port
DEFINE LCD_EBIT  2                                ;     Enable bit
DEFINE LCD_RSREG PORTB                            ; LCD Register Select port
DEFINE LCD_RSBIT 1                                ;     Register Select bit
DEFINE LCD_BITS  4                                ; LCD bus size (4 or 8 bits)
DEFINE LCD_LINES 2                                ; number of lines on LCD
DEFINE LCD_COMMANDUS 2000                         ; Command delay time in us 
DEFINE LCD_DATAUS 50                              ; Data delay time in us 

SCL VAR PORTA.2                                   ; I2C Clock
SDA VAR PORTA.3                                   ; I2C Data

TempHigh    CON 28                                ; DS1621 High Temp Limit
TempLow     CON 24                                ; DS1621 Low Temp Limit
DS1621      CON $90                               ; DS1621 Slave Address
ConfigReg   VAR BYTE                              
TempC       VAR WORD

;----[Initialization]-----------------------------------------------------------
CMCON = 7
ADCON1 = 15

I2CREAD SDA,SCL,DS1621,$AC,[ConfigReg]            ; Read the configuration
IF ConfigReg.0 = 1 THEN                           ; if in Polling Mode?
    I2CWRITE SDA,SCL,DS1621,$AC,[0]               ; Set it to Continuous Mode
    GOSUB WaitForEE
ENDIF

I2CREAD SDA,SCL,DS1621,$A1,[TempC.LowByte]        ; Read the High Temp Limit
IF TempC != TempHigh THEN                         ; if High limit is incorrect
    I2CWRITE SDA,SCL,DS1621,$A1,[TempHigh]        ;  Write High Limit
    GOSUB WaitForEE
ENDIF

I2CREAD SDA,SCL,DS1621,$A2,[TempC.LowByte]        ; Read the Low Temp Limit
IF TempC != TempLow THEN                          ; if Low limit is incorrect
    I2CWRITE SDA,SCL,DS1621,$A2,[TempLow]         ;  Write Low Limit
    GOSUB WaitForEE
ENDIF

I2CWRITE SDA,SCL,DS1621,$EE,[0]                   ; Start Conversions

;----[Main Program Loop]--------------------------------------------------------
Main:
    PAUSE 900
    I2CREAD SDA,SCL,DS1621,$AC,[ConfigReg]        ; Read the configuration
    LCDOUT $FE,$80,"CONFIG=",IBIN8 ConfigReg
                                                  ; Read the Temperature
    I2CREAD SDA,SCL,DS1621,$AA,[TempC.HighByte, TempC.LowByte]
    LCDOUT $FE,$C0,"  Temp="
    GOSUB ShowTemp

    I2CREAD SDA,SCL,DS1621,$A1,[TempC.HighByte, TempC.LowByte]
    LCDOUT $FE,$94,"    TH="
    GOSUB ShowTemp
    
    I2CREAD SDA,SCL,DS1621,$A2,[TempC.HighByte, TempC.LowByte]
    LCDOUT $FE,$D4,"    TL="
    GOSUB ShowTemp
    
GOTO Main

;----[Show Temp on LCD]----------------------------------------------------------
ShowTemp:
    LCDOUT DEC TempC.HighByte
    IF TempC.7 THEN
        LCDOUT ".5  "
    ELSE
        LCDOUT ".0  "
    ENDIF
RETURN

;----[Wait for DS1621 EEPROM Write]----------------------------------------------
WaitForEE:
    REPEAT                                        ; Wait for EEPROM write
        I2CREAD SDA,SCL,DS1621,$AC,[ConfigReg]
        LCDOUT $FE,$80,"CONFIG=",IBIN8 ConfigReg
    UNTIL ConfigReg.4 = 0
RETURN