Using LCD from Mechatronics Demo Board

[Michlis]

After all, the LCD works. Here is the code that I use to display "1234":

PAUSE 1000 'wait for LCD start up

LCDPS = %00110001 'Selecting the frame prescale

LCDSE0.0 = 1 'Segment pins
LCDSE0.1 = 1
LCDSE0.2 = 1
LCDSE0.3 = 1
LCDSE0.6 = 1
LCDSE1.3 = 1
LCDSE2.0 = 1
LCDSE2.5 = 1
LCDSE2.6 = 1
LCDSE2.7 = 1

LCDCON = %01000011 'Multiplex,bias,timing, sleep

LCDDATA0 = %01001000 'initial LCD values "1234"
LCDDATA1 = %00001000
LCDDATA2 = %10100000
LCDDATA3 = %00000000
LCDDATA4 = %00001000
LCDDATA5 = %11100000
LCDDATA6 = %00001100
LCDDATA7 = %00000000
LCDDATA8 = %10100000
LCDDATA9 = %01001000
LCDDATA10 = %00000000
LCDDATA11 = %00000000

PIR2.4 = 0 'clearing LCD interrupt flag

LCDCON = %01010011 'enabling bias voltage pins
LCDCON = %11010011 'enabling the LCD module

however, I have problems when trying to run PWM module while using LCD. I will post about it soon.

[Michlis]

As mentioned above, I have problems when trying to use LCD (code above) and HPWM at the same time.

This is my HPWM program:

'Connections:
'SW2->RD1 increase switch
'SW3->RA4 decrease switch
'P1->Vdd motor turned on constantly
'RC5/CCP1->N2 CCP1 is pwm output pin
'DC motor is connected to DRIVE 1 and DRIVE 2



'HPWM initialization
duty VAR WORD ' Duty cycle value )

TRISC.5 = 0 ' Set PORTC.5 (CCP1) to output
CCP1CON = %00001100 ' Set CCP1 to PWM

T2CON = %00000101 ' Turn on Timer2, Prescale=4

PR2 = 249 ' Set PR2 to get 1KHz out

duty = 500 ' Set duty cycle to 50%


up var PORTD.1 'user-friendly names for ports
down var PORTA.4

'Main program loop
loop:

CCP1CON.4 = duty.0 ' Store duty to registers as
CCP1CON.5 = duty.1 ' a 10-bit word
CCPR1L = DUTY >> 2

'check if button "up" is pressed and duty is not maximum
IF (up=0) AND (duty<1000) THEN
duty=duty+50
PAUSE 200
ENDIF

'similar as before but for reducing the speed
IF (down=0) AND (duty>0) THEN
duty=duty-50
PAUSE 200
ENDIF

GoTo loop ' Do it forever
End

When I combine these two programs (first LCD then HPWM) it starts to work that is I get "1234" on the LCD and then motor starts to turn but only for 2-3sec. Later is just stops. It looks like PWM signal just dies...?!
I have no idea why these two modules (LCD and HPWM) cannot work togather? I have checked the pins and timing sources but don't see any possible conflicts?

[skimask]

IF (down=0) AND (duty>0) THEN
duty=duty-50 : PAUSE 200
ENDIF

If duty is 10 and you subtract 50 from it, you'll end up with a negative number, which PBP doesn't handle. I think you want the lines to be:
IF (down = 0) AND (duty => 50) THEN blah blah blah...

[mister_e]

Nah, PBP handle it. if 0-50 in a byte variable will return 205 or 206.

[skimask]

Nah, PBP handle it. if 0-50 in a byte variable will return 205 or 206.

But 'duty' is a word and, if it does end up being a 'negative number', it'll be above the 1000 limit set in the IF/THEN above and nothing will happen to 'duty' and the program will appear to go stupid.

[mister_e]

<table><td></td><td>hum hum... pfff i knew... it was a test to know if you follow... HUM HUM</td><td></td></table>

[skimask]

hum... pfff i knew... it was a test to know if you follow... HUM HUM

Do I get anything as a prize?

[Michlis]

If duty is 10 and you subtract 50 from it, you'll end up with a negative number

You are of course right, but I start the program with duty=500 and use only +/-50 steps, so this IF statement is correct in my case.

After some time I found the bug. At first I set all LCDSEn registers and it was a mistake since the LCD uses only few pins, so my button input pins were in segment functionality instead of I/O. Now I only set the segment pins that are actually used by LCD.