I2C lcd driver

[shantanu@india]

Hi,
I've purchased this I2C backpack for 16X2 HD44780 based alphanumeric display.
I'm confused about slave address. The PCF8574 says that to write to the LCD I need to use 0x4E which is reasonable since A0/A1/A2 are all pulled up internally. But the seller says to use 0x3F.
I also need some assistance in writing code for this module.
Can anyone help please?

[rick.curl]

Hi Shantanu-
Not my area of expertise, but I did remember THIS THREAD that may be what you're looking for.

-Rick

[shantanu@india]

Thank you so much Rick.
Need to study and then write my own code.  both in Proton and Python

[midali]

Hi Shantanu,

This code may be help you . This code was posted in this forum  :

example:

Code Select Expand

Device = 18F46K20
Declare Xtal = 8
Declare All_Digital = true
Declare Watchdog = On
Declare Slow_Bus On
Clear

Include "I2CPrintHardCommand.inc"
TRISA=%11111111
TRISB=%00000000
TRISC=%10011111
TRISD=%00000000
TRISE=%00000011
PORTA=0
PORTB=0
PORTC=0
PORTD=0
PORTE=0
Dim lights As Byte
lights = 0
DelayMS 500 'Short delay to stabilize the controller
Main:
Cls
If lights = 0 Then
Print $FE, 3 'Backlight on
EndIf

DelayMS 500

Print At 1,1, "  PCF8574T DISPLAY  "
DelayMS 5
Print At 2,1, "TEST TEST  TEST TEST"
DelayMS 5
Print At 3,1, "20 x 4 lines display"
DelayMS 5
Print At 4,1, "  PROTON BASIC    "
DelayMS 500

lights = 1
If lights = 1 Then
Print $FE, 4 'Backlight off
EndIf
DelayMS 500
lights = 0
GoTo Main

Config_Start
FOSC = HS ;HS oscillator
FCMEN = On ;Fail-Safe Clock Monitor enabled
IESO = OFF ;Oscillator Switchover mode disabled
PWRT = On ;PWRT enabled
BOREN = SBORDIS ;Brown-out Reset enabled in hardware only (SBOREN is disabled)
BORV = 18 ;VBOR set to 1.8 V nominal
WDTEN = On ;WDT is controlled by SWDTEN bit of the WDTCON register
WDTPS = 8192 ;1:8192 işlemci çekirdeği 8 saniye çalışmazsa sistem resetlenir.
CCP2MX = PORTC ;CCP2 input/output is multiplexed with RC1
PBADEN = OFF ;PORTB<4:0> pins are configured as analog input channels on Reset
LPT1OSC = OFF ;Timer1 configured for higher power operation
HFOFST = OFF ;HFINTOSC starts clocking the CPU without waiting for the oscillator to stablize.
MCLRE = On ;MCLR pin enabled; RE3 input pin disabled
STVREN = On ;Stack full/underflow will cause Reset
LVP = OFF ;Single-Supply ICSP enabled
XINST = OFF ;Instruction set extension and Indexed Addressing mode disabled (Legacy mode)
Debug = OFF ;Background debugger disabled, RB6 and RB7 configured as general purpose I/O pins
Cp0 = OFF ;Block 0 (000800-003FFFh) not code-protected
CP1 = OFF ;Block 1 (004000-007FFFh) not code-protected
CP2 = OFF ;Block 2 (008000-00BFFFh) not code-protected
CP3 = OFF ;Block 3 (00C000-00FFFFh) not code-protected
CPB = OFF ;Boot block (000000-0007FFh) not code-protected
CPD = OFF ;Data EEPROM not code-protected
WRT0 = OFF ;Block 0 (000800-003FFFh) not write-protected
WRT1 = OFF ;Block 1 (004000-007FFFh) not write-protected
WRT2 = OFF ;Block 2 (008000-00BFFFh) not write-protected
WRT3 = OFF ;Block 3 (00C000h-00FFFFh) not write-protected
WRTC = OFF ;Configuration registers (300000-3000FFh) not write-protected
WRTB = OFF ;Boot Block (000000-0007FFh) not write-protected
WRTD = OFF ;Data EEPROM not write-protected
EBTR0 = OFF ;Block 0 (000800-003FFFh) not protected from table reads executed in other blocks
EBTR1 = OFF ;Block 1 (004000-007FFFh) not protected from table reads executed in other blocks
EBTR2 = OFF ;Block 2 (008000-00BFFFh) not protected from table reads executed in other blocks
EBTR3 = OFF ;Block 3 (00C000-00FFFFh) not protected from table reads executed in other blocks
EBTRB = OFF ;Boot Block (000000-0007FFh) not protected from table reads executed in other blocks
Config_End

;**** End of Fuse Configurator Settings ****
;-------------------------------------------------------------------------------
End


I2CHardPrintCommand:

Code Select Expand

#Disable Print                          ;Disable the Proton Print command   

  ;***************************************************************************************************************
  ; Configure items to suit your LCD and I2C hardware, I2CPrint_DataOnHighBits remmed if data is on low bits    *
  ;                                                                                                              *
  Symbol I2CPrint_address        = %01001110  ' PCF8574 Slave Address 0,1,1,1,A2,A1,A0,RW  where W=0          *
  Symbol I2CPrint_InitForLCDLines = $28        ' $28 for two lines or 4 lines                                              *
  Symbol I2CPrint_RS              = %00000001  '                                                                *
  Symbol I2CPrint_RW              = %00000010  '                                                                *
  Symbol I2CPrint_E              = %00000100  '                                                                *
  Symbol I2CPrint_BackLight      = %00001000  '                                                                *
  $define I2CPrint_DataOnHighBits              '                                                                *
  ;***************************************************************************************************************
 
  Symbol I2CPrint_RS_E          = I2CPrint_RS | I2CPrint_E
 
  $ifdef I2CPrint_DataOnHighBits
    Symbol I2CPrint_Init1          = %00110000
    Symbol I2CPrint_Init1_E        = %00110000 | I2CPrint_E
    Symbol I2CPrint_Init2          = %00110000
    Symbol I2CPrint_Init2_E        = %00110000 | I2CPrint_E
    Symbol I2CPrint_Init3          = %00100000
    Symbol I2CPrint_Init3_E        = %00100000 | I2CPrint_E
  $else
    Symbol I2CPrint_Init1          = %00000011
    Symbol I2CPrint_Init1_E        = %00000011 | I2CPrint_E
    Symbol I2CPrint_Init2          = %00000011
    Symbol I2CPrint_Init2_E        = %00000011 | I2CPrint_E
    Symbol I2CPrint_Init3          = %00000010
    Symbol I2CPrint_Init3_E        = %00000010 | I2CPrint_E
  $endif

  Dim BPF As Byte System
  Symbol I2CPrint_tComOrData = BPF.0
  Symbol I2CPrint_tInitialised = BPF.1

  Dim I2CPrint_PrintStore As Byte
  Dim I2CPrint_PrintData As Byte
  Dim I2CPrint_HighData As Byte
  Dim I2CPrint_LowData As Byte
  Dim I2CPrint_dummy As Byte
  Dim I2CPrint_RSFlag As Byte
  Dim Backlight_State As Byte

  GoTo I2CPrintCommand_End

  @Print                                              ; assembler Print redirect
  Wreg_Byte I2CPrint_PrintStore                      ; save the W Register

  If I2CPrint_tInitialised = 0 Then                  ; Has LCD been inititalised?
    DelayMS 100                                      ; Power-on delay for slow display types
    HBusOut I2CPrint_address, [I2CPrint_Init1_E]      ; E hi and send command nibble 0011 (3)   
    HBusOut I2CPrint_address, [I2CPrint_Init1]        ; E lo   
    DelayMS 20
    HBusOut I2CPrint_address, [I2CPrint_Init2_E]      ; E hi and send command nibble 0011 (3)   
    HBusOut I2CPrint_address, [I2CPrint_Init2]        ; E lo   
    DelayMS 20
    HBusOut I2CPrint_address, [I2CPrint_Init3_E]      ; E hi and send command nibble 0010 (2)   
    HBusOut I2CPrint_address, [I2CPrint_Init3]        ; E lo   
    DelayMS 20
    I2CPrint_PrintData = I2CPrint_InitForLCDLines    ; 4 bit mode and n lines
    GoSub I2CPrint_SendControl
    I2CPrint_PrintData = $0C                          ; enable display, cursor and blink off
    GoSub I2CPrint_SendControl
    I2CPrint_PrintData = $06                          ; move cursor after each write
    GoSub I2CPrint_SendControl                   
    I2CPrint_PrintData = $80                          ; goto column 1 line 1
    GoSub I2CPrint_SendControl
    Set I2CPrint_tInitialised                        ; Indicate that the LCD is initialised
  EndIf

  I2CPrint_PrintData = I2CPrint_PrintStore
  If I2CPrint_PrintData = 0xFE Then                  ; it is a command header
    I2CPrint_RSFlag = 0                              ; clear a flag so we know the next byte will be a command
  Else
    If I2CPrint_RSFlag = 0 Then                      ; this is a command byte
      If I2CPrint_PrintData = 03 Then
        Backlight_State = I2CPrint_BackLight
      ElseIf I2CPrint_PrintData = 04 Then
        Backlight_State = 0
      Else
        GoSub I2CPrint_SendControl
      End If
    Else
      GoSub I2CPrint_SendData
    EndIf
    I2CPrint_RSFlag = 1                              ; set the flag so the next byte will be send as Data
  EndIf                                   
  Byte_Wreg I2CPrint_PrintStore                      ; restore the W register
  Return

' ****************************************************************************
' **                            S U B R O U T I N E S                      **
' ****************************************************************************

I2CPrint_SendData:
  $ifdef I2CPrint_DataOnHighBits
    I2CPrint_HighData = I2CPrint_PrintData & %11110000            ; mask LSBs
    I2CPrint_LowData = I2CPrint_PrintData << 4                    ; shift left
  $else
    I2CPrint_LowData = I2CPrint_PrintData & %00001111            ; mask MSBs
    I2CPrint_HighData = I2CPrint_PrintData >> 4                  ; shift Right
  $endif

  I2CPrint_dummy = I2CPrint_RS_E | I2CPrint_HighData              ; data and e hi
  I2CPrint_dummy = I2CPrint_dummy | Backlight_State              ; data and e hi and bls
  HBusOut I2CPrint_address, [I2CPrint_dummy]           
  I2CPrint_dummy = I2CPrint_RS | I2CPrint_HighData                ; data and e lo
  I2CPrint_dummy = I2CPrint_dummy | Backlight_State              ; data and e lo and bls
  HBusOut I2CPrint_address, [I2CPrint_dummy]             
  I2CPrint_dummy = I2CPrint_RS | Backlight_State                  ; data and e hi
  HBusOut I2CPrint_address, [I2CPrint_dummy]                      ; Delay, RS on throughout
  I2CPrint_dummy = I2CPrint_RS_E | I2CPrint_LowData              ; data and e hi
  I2CPrint_dummy = I2CPrint_dummy | Backlight_State              ; data and e hi and bls
  HBusOut I2CPrint_address, [I2CPrint_dummy]             
  I2CPrint_dummy = I2CPrint_RS | I2CPrint_LowData                ; data and e lo
  I2CPrint_dummy = I2CPrint_dummy | Backlight_State              ; data and e lo and bls
  HBusOut I2CPrint_address, [I2CPrint_dummy]
  Return
 
I2CPrint_SendControl:
  $ifdef I2CPrint_DataOnHighBits
    I2CPrint_HighData = I2CPrint_PrintData & %11110000            ; mask LSBs
    I2CPrint_LowData = I2CPrint_PrintData << 4                    ; shift left
  $else
    I2CPrint_LowData = I2CPrint_PrintData & %00001111            ; mask MSBs
    I2CPrint_HighData = I2CPrint_PrintData >> 4                  ; shift Right
  $endif

  I2CPrint_dummy = I2CPrint_E | I2CPrint_HighData                ; data and e hi
  I2CPrint_dummy = I2CPrint_dummy | Backlight_State              ; data and e hi and bls
  HBusOut I2CPrint_address, [I2CPrint_dummy]             
  I2CPrint_dummy = I2CPrint_HighData | Backlight_State            ; data and e lo and bls
  HBusOut I2CPrint_address, [I2CPrint_dummy]             
  I2CPrint_dummy = Backlight_State                                ;
  HBusOut I2CPrint_address, [I2CPrint_dummy]                      ; Delay
  I2CPrint_dummy = I2CPrint_E | I2CPrint_LowData                  ; data and e hi
  I2CPrint_dummy = I2CPrint_dummy | Backlight_State              ; data and e hi and bls
  HBusOut I2CPrint_address, [I2CPrint_dummy]             
  I2CPrint_dummy = I2CPrint_LowData | Backlight_State            ; data and e lo and bls
  HBusOut I2CPrint_address, [I2CPrint_dummy]       
  Return

I2CPrintCommand_End:

[shantanu@india]

Thanks Midali