Interfacing with Arduino I2C LCD

[doctordhd]

The PIC numbering system was getting me confused so I spoke to an engineer at Microchip and this is what I was told...

The 12 in the 12F629 means it is an 8 pin chip. (I didn't ask why 12 means 8 or why they just didn't just call it an 8Fxxx)

The 6 after the F means that it has a 14 bit memory core, since anything other (? # > 5) has a 14 bit memory core.

A 12F5xx chip would be an 8 pin chip with a 12 bit memory core...

So it does not seem to a 12-bit core problem but rather an overall memory problem.

The 12F629 has 1k x 14 memory (there's that 14 bit core again), where as
the 12F1822 has 2K 14 memory.

I ordered some 12F1822s to see if I can get Darrel's program working.

[doctordhd]

Here is the thread in which I believe Darrel was using a 12F1822.

Post #3

http://support.melabs.com/threads/98...F8574-20x4-LCD

[doctordhd]

Hmmm, unfortunately, I just figured out that my Silver version of PBP3.0 doesn't support the 12F1822...

[richard]

a pic12f1xxx is an enhanced midrange device . they have twice the stack capacity of a 12f6xx device , apart from more memory etc ....

[doctordhd]

Thanks to everyone that helped out.

I have gotten a modified version of Darrel's code to run on a 12F683 which has 2K of memory.

I am using an LCD 1602 and I don't see any Jumping Jacks.

; Filename    : 632-I2C-LCD for 12F683.pbp
; Author      : Darrel Taylor 
; Created     : Mon Feb 24 2014
;             : May 27, 2015 adapted for the 12F683 
; Processor   : PIC12F683
; Compiler    : PicBasic Pro 3.0.7.x or higher
; Description : Uses PCF8574 Port expander to interface with HD44780 LCD
;

;----[Oscillator Setup]---------------------------------------------------------
define OSC 20 
define I2C_SLOW 1

;----[Aliases]------------------------------------------------------------------
SDA         VAR GPIO.0       ; I2C Data pin
SCL         VAR GPIO.1       ; I2C Clock Pin

;----[Initialize Hardware]------------------------------------------------------
ANSEL = 0             ; Make Analog inputs digital

';----[Setup LCD using PCF8574 Port Expander]------------------------------------
LCD_Addr    CON $40           ; A0, A1, A2 grounded
true        con 1
false       con 0
INCLUDE "LCD_PCF8574.pbp"     ;  Init LCD using I2C and PCF8574

;----[Variables]----------------------------------------------------------------
LoopCount   VAR BYTE
CustChar    VAR BYTE

;----[Program Start]------------------------------------------------------------
Backlight = 0                 ; Turn on LCD Backlight
LoopCount     = 0
ARRAYWRITE LCD_Buff,["   LCD PCF8574"] : LCD_WriteBuff

;----[Custom Characters]-(Jumping Jacks)----------------------------------------
ARRAYWRITE LCD_Buff,[$FE,$40,$00,$04,$0A,$04,$0E,$15,$0A,$11]:LCD_WriteBuff ' #0  
ARRAYWRITE LCD_Buff,[$FE,$48,$00,$04,$0A,$04,$1F,$04,$0A,$0A]:LCD_WriteBuff ' #1  
ARRAYWRITE LCD_Buff,[$FE,$50,$04,$0A,$15,$0E,$04,$0A,$0A,$00]:LCD_WriteBuff ' #2 

;----[Main Program Loop]--------------------------------------------------------
Main:
   ARRAYWRITE LCD_Buff,[$FE,$C0,"Count = ",DEC LoopCount,"   "] : LCD_WriteBuff
   PAUSE 200
   LoopCount = LoopCount + 1
   
   CustChar = LoopCount//3   ; Jumping Jacks Sequence
   ARRAYWRITE LCD_Buff,[$FE,$9D,CustChar] : LCD_WriteBuff
GOTO Main

[doctordhd]

Commented out the lines...

ARRAYWRITE LCD_Buff,[" LCD PCF8574"] : LCD_WriteBuff

and

ARRAYWRITE LCD_Buff,[$FE,$C0,"Count = ",DEC LoopCount," "] : LCD_WriteBuff

Changed the $9D to a $C0 in

ARRAYWRITE LCD_Buff,[$FE,$C0,CustChar] : LCD_WriteBuff ' $C0 was $9D

and now the little guy is doing Jumping Jacks in the lower left hand corner.

Thanks again!

[n0yox]

I am trying to make this code work with a 16F629A and all I get is a blinking back light with the modified code below.I am probably missing something simple?

Thanks,

; Filename : Test_LCD_PCF8574.pbp
; Author : Darrel Taylor
; Created : Mon Feb 24 2014
; Processor : 16F629A
; Compiler : PicBasic Pro 3.0.6.x or higher
; Description : Uses PCF8574 Port expander to interface with HD44780 LCD
;

;----[16f629A Hardware Configuration]-------------------------------------------
#config
__config _INTOSC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _LVP_OFF & _CP_ON & _BODEN_OFF
#endconfig



;----[Aliases]------------------------------------------------------------------
SDA var porta.7
SCL var porta.6
;----[Initialize Hardware]------------------------------------------------------
CMCON = 7 'CHANGES PORTA TO DIGITAL
;----[Setup LCD using PCF8574 Port Expander]------------------------------------
LCD_Addr CON $7E
INCLUDE "LCD_PCF8574.pbp" ; Include LCD module for PCF8574

;----[Variables]----------------------------------------------------------------
LoopCount VAR BYTE
CustChar VAR BYTE

;----[Program Start]------------------------------------------------------------
Backlight = 0 ; Turn on LCD Backlight
ARRAYWRITE LCD_Buff,[" LCD PCF8574"] : LCD_WriteBuff
LoopCount= 0

;----[Custom Characters]-(Jumping Jacks)----------------------------------------
ARRAYWRITE LCD_Buff,[$FE,$40,$00,$04,$0A,$04,$0E,$15,$0A,$11]:LCD_WriteBuff ' #0
ARRAYWRITE LCD_Buff,[$FE,$48,$00,$04,$0A,$04,$1F,$04,$0A,$0A]:LCD_WriteBuff ' #1
ARRAYWRITE LCD_Buff,[$FE,$50,$04,$0A,$15,$0E,$04,$0A,$0A,$00]:LCD_WriteBuff ' #2

;----[Main Program Loop]--------------------------------------------------------
Main:
ARRAYWRITE LCD_Buff,[$FE,$C0,"Count = ",DEC LoopCount," "] : LCD_WriteBuff
PAUSE 200
LoopCount = LoopCount + 1

CustChar = LoopCount//3 ; Jumping Jacks Sequence
ARRAYWRITE LCD_Buff,[$FE,$C0,CustChar] : LCD_WriteBuff
GOTO Main

[n0yox]

I did delete these two lines

ARRAYWRITE LCD_Buff,[" LCD PCF8574"] : LCD_WriteBuff

ARRAYWRITE LCD_Buff,[$FE,$C0,"Count = ",DEC LoopCount," "] : LCD_WriteBuff

and Change this line

ARRAYWRITE LCD_Buff,[$FE,$C0,CustChar] : LCD_WriteBuff ' $C0 was $9D