LCD_IO 10 provides support for character LCD modules that use an I2C/TWI interface based on the PCF8574 or PCF8574A I/O expander. This for the 16F877A, but, it can easily be adapted for any other microcontrollers.
A 2 by 16 LCD is assumed with the LCD being driven using an LCD I2C adapter. Two types are supported the YwRobot LCD1602 IIC V1 / a Sainsmart LCD_PIC I2C adapter or the Ywmjkdz I2C adapter with pot bent over top of chip.
Example - Joy-IT/Raspberry Pi LCD PCB:
This demonstrates using Joy-IT/Raspberry Pi LCD PCB by changing the I2C_LCD_* constants that control this mode of LCD_IO operations.
#chip AVR128DA28, 24
#option explicit
// Define Hardware I2C settings
HI2CMode Master
#DEFINE HI2C_DATA PORTA.2
#DEFINE HI2C_CLOCK PORTA.3
#DEFINE LCD_IO 10
// LCD_I2C_Address_1 is not required because default address
// #DEFINE LCD_I2C_ADDRESS_1 0X4E
// This settings are suited for a joy-it adapter. Its made for the Raspberry Pi.
// This changes the default expander port mappings.
#DEFINE I2C_LCD_E I2C_LCD_BYTE.7
#DEFINE I2C_LCD_RW I2C_LCD_BYTE.5
#DEFINE I2C_LCD_RS I2C_LCD_BYTE.4
#DEFINE I2C_LCD_BL I2C_LCD_BYTE.6
#DEFINE I2C_LCD_D4 I2C_LCD_BYTE.0
#DEFINE I2C_LCD_D5 I2C_LCD_BYTE.1
#DEFINE I2C_LCD_D6 I2C_LCD_BYTE.2
#DEFINE I2C_LCD_D7 I2C_LCD_BYTE.3
// ----- Main body of program commences here.
Print "Hello World"Example - Multiple LCDs:
This demonstrates reading a DS18B20 and showing the results on multiple LCDs.
#chip mega328p, 16
#include <DS18B20.h>
; ----- Define Hardware settings
' Define I2C settings - CHANGE PORTS
#DEFINE I2C_MODE Master
#DEFINE I2C_DATA PORTC.4
#DEFINE I2C_CLOCK PORTC.5
#DEFINE I2C_DISABLE_INTERRUPTS ON
'''Set up LCD
#DEFINE LCD_IO 10
#DEFINE LCD_I2C_ADDRESS_1 0x4E ; LCD 1
#DEFINE LCD_I2C_ADDRESS_2 0x4C ; LCD 2
; ----- Constants
' DS18B20 port settings - this is required
#DEFINE DQ PortC.3
; ----- Quick Command Reference:
'''Set LCD_10 to 10 for the YwRobot LCD1602 IIC V1 or the Sainsmart LCD_PIC I2C adapter
'''Set LCD_10 to 12 for the Ywmjkdz I2C adapter with pot bent over top of chip
; ----- Variables
dim TempC_100 as word ' a variabler to handle the temperature calculations
dim DSdataRaw as Integer
; ----- Main body of program commences here.
'Change to the correct LCD by setting LCD_I2C_ADDRESS_Current to the correct address then write to LCD.
LCD_I2C_ADDRESS_Current = LCD_I2C_ADDRESS_1: DisplayInformation ( 1 )
LCD_I2C_ADDRESS_Current = LCD_I2C_ADDRESS_2: DisplayInformation ( 1 )
wait 4 s
LCD_I2C_ADDRESS_Current = LCD_I2C_ADDRESS_1: CLS
LCD_I2C_ADDRESS_Current = LCD_I2C_ADDRESS_2: CLS
ccount = 0
Do forever
' The function readtemp12 returns the raw value of the sensor.
' The sensor is read as a 12 bit value therefore each unit equates to 0.0625 of a degree
DSdataRaw = readtemp12 ; save to this variable to prevent the delay bewtween screen up dates
' The function readtemp returns the integer value of the sensor
DSdata = readtemp
LCD_I2C_ADDRESS_Current = LCD_I2C_ADDRESS_1: DisplayInformation ( 2 ) ; update LCD1
LCD_I2C_ADDRESS_Current = LCD_I2C_ADDRESS_2: DisplayInformation ( 2 ) ; update LCD2
DSdata = DSdataRaw ; Set the data
LCD_I2C_ADDRESS_Current = LCD_I2C_ADDRESS_1: DisplayInformation ( 3 ) ; update LCD1
DSdata= DSdataRaw ; Set the data
LCD_I2C_ADDRESS_Current = LCD_I2C_ADDRESS_2: DisplayInformation ( 3 ) ; update LCD2
ccount++
wait 1 s
loop
End
Sub DisplayInformation ( LCDCommand )
Select case LCDCommand
Case 1
CLS
print "GCBASIC 2021"
locate 1,0
print "DS18B20 Demo"
Case 2
' Display the integer value of the sensor on the LCD
locate 0,0
print hex(ccount)
print " Ceil"
locate 0,8
print DSdata
print chr(223)+"C"+" "
Case 3
' Display the integer and decimal value of the sensor on the LCD
SignBit = DSdata / 256 / 128
If SignBit = 0 Then goto Positive
' its negative!
DSdata = ( DSdata # 0xffff ) + 1 ' take twos comp
Positive:
' Convert value * 0.0625. Mulitple value by 6 then add result to multiplication of the value with 25 then divide result by 100.
TempC_100 = DSdata * 6
DSdata = ( DSdata * 25 ) / 100
TempC_100 = TempC_100 + DSdata
Whole = TempC_100 / 100
Fract = TempC_100 % 100
If SignBit = 0 Then goto DisplayTemp
Print "-"
DisplayTemp:
locate 1,0
print hex(ccount)
print " Real"
locate 1,8
print str(Whole)
print "."
' To ensure the decimal part is two digits
Dig = Fract / 10
print Dig
Dig = Fract % 10
print Dig
print chr(223)
print "C"+" "
End Select
end sub