Example Code for Simple Debugging With LCD Display

[William Roth]

This is a an example that shows a way to do simple debugging by viewing the contents of various registers on an LCD Display. Many times when developing a program I need to check the contents of a register or two but I am not too keen on running a debugger.

So I wrote the Print_reg sub to do this. Required are a $5 4x20 LCD Display with a $1 I2C Expander. Only two pins needed to the PIC. Optionally a 16x 2 display could be used, but the code will need modification.

Here is the complete code. Feel free to change or modify as you wish.

 '''An Example Program for Great Cow Basic.

 ''' Using a 4x20 LCD Display for Simple Debugging

 '''@author         William R
 '''@date           24.04.2015
 '''******************************************************

#chip 16F1829, 16

#define I2C_MODE Master
#define I2C_DATA PORTA.2
#define I2C_CLOCK PORTC.0
#define I2C_DISABLE_INTERRUPTS ON

#define LCD_IO 10
#define LCD_SPEED FAST
#define LCD_Backlight_On_State  1
#define LCD_Backlight_Off_State 0
CLS

' Splash Screen
Locate 0,0: Print "Great Cow Basic .94"
Locate 1,0: Print ChipNameStr
wait 2 s
CLS 'Clear the display

'Manually Setup  Timer2
T2CON = b'01111011    ;Prescaler 1:64, Postscaler 1:16
TMR2 = 0  'Make sure timer2 value = 0
'The timer is now initialized but not started.

       'Verify T2CCON register

''' ************   DEBUGGING ******************
'PRINT_REG (LCD Line, RegisterName)
' If Line is ommited will print on line 0
Print_Reg (0,T2CON)   'Print the contents of up to 4 Registers
Print_Reg (1,PR2)     'Each register takes 1 line
Print_Reg (2,OSCCAL)
Print_Reg (3,PIE1)
''' *******************************************

Stop   'Stop the program here

'Start timer 2
SET T2CON.2 ON
wait 100 us

SUB ISR1 'Flash LED to test inpterrupt
   Set PortA.5 ON
   WAIT 2 ms
   Set PortA.5 Off
END SUB

SUB Print_reg (optional In LN = 0, IN Register)

   'CLS   'Optional
   if LN > 3 then LN = 0

   Locate LN,0
   Print "RG": PRINT LN: Print "  "
   Print register.7: Print " "
   Print register.6: Print " "
   Print register.5: Print " "
   Print register.4: Print " "
   Print register.3: Print " "
   Print register.2: Print " "
   Print register.1: Print " "
   Print register.0

END SUB

sub stop  'stops code
do
loop
end sub

[Jim giordano]

Looks good, thanks :)