Coding Parallel LCD w/BS2 - decimal point question

sylveeski · 2014-03-14 13:46

Hi,

I'm trying to get my LCD to output values between 0 and 255. If I start at 0 and increase the numbers, they show up properly. For example, 25 shows up as 25. Then, when I get to 3 digit values, they show up properly as well.

The problem is when I go down from 3 digit numbers to 2 digit numbers. The LCD output stays in 3 digit mode so now my actual output of 25 shows up as 250. The LCD can't get back down to showing 2 or 1 digits unless I reset the whole program.

I'm sure I just have to change a line or something in the code, but I can't figure it out. Can you help? Here's what my code looks like. (Note the variable "TempC" goes from 0 to 255)

'
' {$STAMP BS2}
' {$PBASIC 2.5}
'
' =========================================================================

'

[ Constants ]

LcdCls CON $01 ' clear the LCD
LcdHome CON $02 ' move cursor home
LcdCrsrL CON $10 ' move cursor left
LcdCrsrR CON $14 ' move cursor right
LcdDispL CON $18 ' shift chars left
LcdDispR CON $1C ' shift chars right
LcdDDRam CON $80 ' Display Data RAM control
LcdCGRam CON $40 ' Character Generator RAM
LcdLine1 CON $80 ' DDRAM address of line 1

'

[ Variables ]

char VAR Byte ' character sent to LCD
idx VAR Byte ' loop counter
index VAR Byte ' index counter
flag VAR Bit ' flag variable
Datain VAR Byte ' Variable to hold incoming number (0 to 255)
TempC VAR Word ' Temp in Celcius
TempSpan VAR Word ' Full Scale input span in tenths of degrees.

'

[ EEPROM Data ]

Msg DATA "Go To:", 0 ' store message

'

[ Initialization ]

TempSpan = 5800 ' Declare span. Set Vref to .50V and
' 0 TO 255 res. will be spread over 50
' (hundredths).

Reset:
DIRL = %11111110 ' setup pins for LCD
PAUSE 100 ' let the LCD settle

LCD_Init:
LcdBus = %0011
PULSOUT E, 3
PAUSE 5
PULSOUT E, 3
PULSOUT E, 3
LcdBus = %0010 ' 4-bit mode
PULSOUT E, 1
char = %00101000 ' 2-line mode
GOSUB LCD_Cmd
char = %00001100 ' on, no crsr, no blink
GOSUB LCD_Cmd
char = %00000110 ' inc crsr, no disp shift
GOSUB LCD_Cmd

char = LcdCls ' clear the LCD
GOSUB LCD_Cmd
PAUSE 20
idx = Msg ' get EE address of message
' (loop counter)
GOSUB Write_Message
'PAUSE 20 ' wait 2 seconds

'char = LcdLine2 ' switch to line 2
'GOSUB LCD_Cmd
'PAUSE 20
'idx = Two ' get EE address of message
'GOSUB Write_Message

LCD_Main:
char = LcdLine1 + 9 ' Position cursor after word
GOSUB LCD_Cmd ' Write the value of temperature
GOSUB Write_Var
'PAUSE 500
'char = LcdLine2 + 4 ' Position cursor after word
'GOSUB LCD_Cmd ' Write Y or N to indicate heater on/off
'GOSUB Write_Var2
'char = LcdLine2 + 12
'GOSUB LCD_Cmd
'GOSUB Write_Var3
RETURN

Write_Message:
DO
READ idx, char ' get character from EE
IF (char = 0) THEN EXIT ' if 0, message is complete
GOSUB LCD_Out ' write the character
idx = idx + 1 ' point to next character
LOOP
RETURN

Write_Var:
flag = 0
FOR index = 3 TO 0 ' handle 3 digits
char = TempC DIG index ' check value of 3 digits
IF char THEN flag = 1 ' is digit a zero?

IF flag = 1 THEN ' strip leading zeros only
char = char + $30 ' if not add ASCII offset
GOSUB LCD_Out ' print it
ENDIF
NEXT
RETURN

LCD_Cmd:
LOW RS ' enter command mode

LCD_Out:
LcdBus = char.HIGHNIB ' output high nibble
PULSOUT E, 3 ' strobe the Enable line
LcdBus = char.LOWNIB ' output low nibble
PULSOUT E, 3
HIGH RS ' return to character mode
RETURN

Publison · 2014-03-14 13:56

When putting code in the thread, use this method.

attachment.php?attachmentid=78421&d=1297987572

It preserves the indentations and makes it more readable.

sylveeski · 2014-03-15 14:26

'[/COLOR]
[COLOR=#333333]' {$STAMP BS2}[/COLOR]
[COLOR=#333333]' {$PBASIC 2.5}[/COLOR]
[COLOR=#333333]'[/COLOR]
[COLOR=#333333]' ================================================== =======================[/COLOR]


[COLOR=#333333]' -----[ Constants ]-------------------------------------------------------[/COLOR]


[COLOR=#333333]LcdCls CON $01 ' clear the LCD[/COLOR]
[COLOR=#333333]LcdHome CON $02 ' move cursor home[/COLOR]
[COLOR=#333333]LcdCrsrL CON $10 ' move cursor left[/COLOR]
[COLOR=#333333]LcdCrsrR CON $14 ' move cursor right[/COLOR]
[COLOR=#333333]LcdDispL CON $18 ' shift chars left[/COLOR]
[COLOR=#333333]LcdDispR CON $1C ' shift chars right[/COLOR]
[COLOR=#333333]LcdDDRam CON $80 ' Display Data RAM control[/COLOR]
[COLOR=#333333]LcdCGRam CON $40 ' Character Generator RAM[/COLOR]
[COLOR=#333333]LcdLine1 CON $80 ' DDRAM address of line 1[/COLOR]




[COLOR=#333333]' -----[ Variables ]-------------------------------------------------------[/COLOR]


[COLOR=#333333]char VAR Byte ' character sent to LCD[/COLOR]
[COLOR=#333333]idx VAR Byte ' loop counter[/COLOR]
[COLOR=#333333]index VAR Byte ' index counter[/COLOR]
[COLOR=#333333]flag VAR Bit ' flag variable[/COLOR]
[COLOR=#333333]Datain VAR Byte ' Variable to hold incoming number (0 to 255)[/COLOR]
[COLOR=#333333]TempC VAR Word ' Temp in Celcius[/COLOR]
[COLOR=#333333]TempSpan VAR Word ' Full Scale input span in tenths of degrees.[/COLOR]


[COLOR=#333333]' -----[ EEPROM Data ]-----------------------------------------------------[/COLOR]


[COLOR=#333333]Msg DATA "Go To:", 0 ' store message[/COLOR]


[COLOR=#333333]' -----[ Initialization ]--------------------------------------------------[/COLOR]


[COLOR=#333333]TempSpan = 5800 ' Declare span. Set Vref to .50V and[/COLOR]
[COLOR=#333333]' 0 TO 255 res. will be spread over 50[/COLOR]
[COLOR=#333333]' (hundredths).[/COLOR]


[COLOR=#333333]Reset:[/COLOR]
[COLOR=#333333]DIRL = %11111110 ' setup pins for LCD[/COLOR]
[COLOR=#333333]PAUSE 100 ' let the LCD settle[/COLOR]


[COLOR=#333333]LCD_Init:[/COLOR]
[COLOR=#333333]LcdBus = %0011[/COLOR]
[COLOR=#333333]PULSOUT E, 3[/COLOR]
[COLOR=#333333]PAUSE 5[/COLOR]
[COLOR=#333333]PULSOUT E, 3[/COLOR]
[COLOR=#333333]PULSOUT E, 3[/COLOR]
[COLOR=#333333]LcdBus = %0010 ' 4-bit mode[/COLOR]
[COLOR=#333333]PULSOUT E, 1[/COLOR]
[COLOR=#333333]char = %00101000 ' 2-line mode[/COLOR]
[COLOR=#333333]GOSUB LCD_Cmd[/COLOR]
[COLOR=#333333]char = %00001100 ' on, no crsr, no blink[/COLOR]
[COLOR=#333333]GOSUB LCD_Cmd[/COLOR]
[COLOR=#333333]char = %00000110 ' inc crsr, no disp shift[/COLOR]
[COLOR=#333333]GOSUB LCD_Cmd[/COLOR]


[COLOR=#333333]char = LcdCls ' clear the LCD[/COLOR]
[COLOR=#333333]GOSUB LCD_Cmd[/COLOR]
[COLOR=#333333]PAUSE 20[/COLOR]
[COLOR=#333333]idx = Msg ' get EE address of message[/COLOR]
[COLOR=#333333]' (loop counter)[/COLOR]
[COLOR=#333333]GOSUB Write_Message[/COLOR]
[COLOR=#333333]'PAUSE 20 ' wait 2 seconds[/COLOR]


[COLOR=#333333]'char = LcdLine2 ' switch to line 2[/COLOR]
[COLOR=#333333]'GOSUB LCD_Cmd[/COLOR]
[COLOR=#333333]'PAUSE 20[/COLOR]
[COLOR=#333333]'idx = Two ' get EE address of message[/COLOR]
[COLOR=#333333]'GOSUB Write_Message[/COLOR]


[COLOR=#333333]LCD_Main:[/COLOR]
[COLOR=#333333]char = LcdLine1 + 9 ' Position cursor after word[/COLOR]
[COLOR=#333333]GOSUB LCD_Cmd ' Write the value of temperature[/COLOR]
[COLOR=#333333]GOSUB Write_Var[/COLOR]
[COLOR=#333333]'PAUSE 500[/COLOR]
[COLOR=#333333]'char = LcdLine2 + 4 ' Position cursor after word[/COLOR]
[COLOR=#333333]'GOSUB LCD_Cmd ' Write Y or N to indicate heater on/off[/COLOR]
[COLOR=#333333]'GOSUB Write_Var2[/COLOR]
[COLOR=#333333]'char = LcdLine2 + 12[/COLOR]
[COLOR=#333333]'GOSUB LCD_Cmd[/COLOR]
[COLOR=#333333]'GOSUB Write_Var3[/COLOR]
[COLOR=#333333]RETURN[/COLOR]


[COLOR=#333333]Write_Message:[/COLOR]
[COLOR=#333333]DO[/COLOR]
[COLOR=#333333]READ idx, char ' get character from EE[/COLOR]
[COLOR=#333333]IF (char = 0) THEN EXIT ' if 0, message is complete[/COLOR]
[COLOR=#333333]GOSUB LCD_Out ' write the character[/COLOR]
[COLOR=#333333]idx = idx + 1 ' point to next character[/COLOR]
[COLOR=#333333]LOOP[/COLOR]
[COLOR=#333333]RETURN[/COLOR]


[COLOR=#333333]Write_Var:[/COLOR]
[COLOR=#333333]flag = 0[/COLOR]
[COLOR=#333333]FOR index = 3 TO 0 ' handle 3 digits[/COLOR]
[COLOR=#333333]char = TempC DIG index ' check value of 3 digits[/COLOR]
[COLOR=#333333]IF char THEN flag = 1 ' is digit a zero?[/COLOR]


[COLOR=#333333]IF flag = 1 THEN ' strip leading zeros only[/COLOR]
[COLOR=#333333]char = char + $30 ' if not add ASCII offset[/COLOR]
[COLOR=#333333]GOSUB LCD_Out ' print it[/COLOR]
[COLOR=#333333]ENDIF[/COLOR]
[COLOR=#333333]NEXT[/COLOR]
[COLOR=#333333]RETURN[/COLOR]


[COLOR=#333333]LCD_Cmd:[/COLOR]
[COLOR=#333333]LOW RS ' enter command mode[/COLOR]


[COLOR=#333333]LCD_Out:[/COLOR]
[COLOR=#333333]LcdBus = char.HIGHNIB ' output high nibble[/COLOR]
[COLOR=#333333]PULSOUT E, 3 ' strobe the Enable line[/COLOR]
[COLOR=#333333]LcdBus = char.LOWNIB ' output low nibble[/COLOR]
[COLOR=#333333]PULSOUT E, 3[/COLOR]
[COLOR=#333333]HIGH RS ' return to character mode[/COLOR]
[COLOR=#333333]RETURN

sylveeski · 2014-03-15 14:26

Is that better? Now does someone know how to fix this?

erco · 2014-03-15 20:04

Try printing two spaces immediately after each digit to erase the previous number. Note that printing a space is very different from moving the cursor.

Alternatively, you could clear the display each time before printing a number.

Sapphire · 2014-03-15 20:15

You need to send a space for each leading zero that you strip off the number, so that the field is always 3 characters wide.

Add the following to the Write_Var: subroutine just before the RETURN

char = " "
IF TempC < 100 THEN GOSUB LCD_Out
IF TempC < 10 THEN GOSUB LCD_Out

A blank space will be added zero, one or two times, depending on the size of the number you are displaying.

Coding Parallel LCD w/BS2 - decimal point question

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