IF Comp {AND/OR Comp...} THEN Label

IF Comp {AND/OR Comp...} THEN

Statement...

ELSE

Statement...

ENDIF

Performs one or more comparisons. Each Comp term can relate a variable to a constant or other variable and includes one of the comparison operators listed previously.

If..Then evaluates the comparison terms for true or false. If it evaluates to true, the operation after the Then is executed. If it evaluates to false, the operation after the Then is not executed. Comparisons that evaluate to 0 are considered false. Any other value is considered true. 

All comparisons are unsigned since PBP only supports unsigned types.  IF..THEN cannot be used to check if a number is less than 0.

IF..THEN can operate in 2 manners. In one form, the THEN in an IF..THEN is essentially a GOTO. If the condition is true, the program will GOTO the label after the THEN. If the condition evaluates to false, the program will continue at the next line after the IF..THEN. Another statement may not be placed after the THEN, it must be a label.

	If Pin0 = 0 Then pushd	' If button connected to Pin0 is pushed (0), jump to label pushd
	If B0 >= 40 Then old	' If the value in variable B0 is greater than or equal to 40, jump to old
	If PORTB.0 Then itson	' If PORTB, pin 0 is high (1), jump to itson
	If (B0 = 10) AND (B1 = 20) Then loop

In the second form, IF..THEN can conditionally execute a group of Statements following the THEN. The Statements must be followed by an ELSE or ENDIF to complete the structure.

	If B0 <> 10 Then
		B0 = B0 + 1
		B1 = B1 - 1
	Endif

	If B0 = 20 Then
		led = 1
	Else
		led = 0
	Endif

INPUT Pin

Makes the specified Pin an input. Pin may be a constant, 0-15, or a variable that contains a number 0-15 (e.g. B0) or a pin name (e.g. PORTA.0).

	INPUT 0		' Make Pin0 an input
	INPUT PORTA.0	' Make PORTA, pin 0 an input

	TRISB.0 = 1		' Set PORTB, pin 0 to an input

	TRISB = %11111111	' Set all of PORTB to inputs

LCDIN {Address,}[Var{,Var...}]

Read LCD RAM at Address and store data to Var.

LCDs have RAM onboard that is used for character memory. Most LCDs have more RAM available that is necessary for the displayable area. This RAM can be written using the LCDOUT instruction. The LCDIN instruction allows this RAM to be read.

It is necessary to connect the LCD read/write line to a PICmicro pin so that it may be controlled to select either a read (LCDIN) or write (LCDOUT) operation. Two DEFINEs control the pin address:

	DEFINE LCD_RWREG PORTE	' LCD read/write pin port
	DEFINE LCD_RWBIT 2	' LCD read/write pin bit

See LCDOUT for information on connecting an LCD to a PICmicro MCU.

    LCDIN [B0]

LCDOUT Item{,Item...}

Display Items on an intelligent Liquid Crystal Display. PBP supports LCD modules with a Hitachi 44780 controller or equivalent. These LCDs usually have a 14- or 16-pin single- or dual-row header at one edge.

If a pound sign (#) precedes an Item, the ASCII representation for each digit is sent to the LCD. LCDOUT (on all devices except 12-bit core) can also use any of the modifiers used with SEROUT2. See the section on SEROUT2 for this information.

LCDOUT $FE, $80 + 4

sets the display to start writing characters at the forth position of the first line. 16x1 displays are usually formatted as 8x2 displays with a break between the memory locations for the first and second 8 characters. 4- line displays also have a mixed up memory map, as shown in the table above.

	LCDOUT $FE, 1, “Hello”	' Clear display and show “Hello”

	LCDOUT $FE,$C0,“World” 	' Jump to second line and show “World”

	LCDOUT B0, #B1		' Display B0 and decimal ASCII value of B1The LCD may be connected to the PICmicro using either a 4-bit bus or an 8-bit bus. If an 8-bit bus is used, all 8 bits must be on one port. If a 4-bit bus is used, it must be connected to either the bottom 4 or top 4 bits of one port. Enable and Register Select may be connected to any port pin. R/W should be tied to ground as the LCDOUT command is write only.

The LCD may be connected to the PICmicro MCU using either a 4-bit bus or an 8-bit bus. If an 8-bit bus is used, all 8 bits must be on one port. If a 4-bit bus is used, the top 4 LCD data bits must be connected to either the bottom 4 or top 4 bits of one port. Enable and Register Select may be connected to any port pin. R/W may be tied to ground if the LCDIN command is not used.

To change this setup, place one or more of the following DEFINEs, all in upper-case, at the top of your PICBASIC PRO™ program:

	' Set LCD Data port
	DEFINE LCD_DREG	PORTB
	' Set starting Data bit (0 or 4) if 4-bit bus
	DEFINE LCD_DBIT	4
	' Set LCD Register Select port
	DEFINE LCD_RSREG	PORTB
	' Set LCD Register Select bit
	DEFINE LCD_RSBIT	1
	' Set LCD Enable port
	DEFINE LCD_EREG	PORTB
	' Set LCD Enable bit
	DEFINE LCD_EBIT	0
	' 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

<<Previous

Next>>