Voltage output from PIC16f628A

[mister_e]

T2CON = %00010101 ' Turn on Timer2, Prescale=4
'
'
'
duty = 100 ' Set duty cycle to 20%

1. your prescaler is not set to 1:16 as said in the calc. Now, it's set to 1:4. Have a look in datasheet section 8.0 register 8-1 T2CON. you'll discover you need to use T2CON=%00000110

2. duty=100 set a duty cycle of 16%... still as per the calc. 20% Duty=125

SerIn SI,T9600,,duty

i think it's invalid.

you should try

SerIn SI,T9600,#duty

In Microcode Studio serial communicator, you have access to the settings. Right to 'send' button there's a little arrow.. click on it, go to line terminator, then check 'No terminator'

[bennamanna]

Gday,

I changed the items you found to be in correct. It still will not output what I send via RS232. It comes up with other numbers. I will repost the code I have ended up with below.

INCLUDE "modedefs.bas" ' Include serial modes
SI VAR PORTB.1 ' Serial Input pin
B0 VAR BYTE
Define OSC 10

Define LCD_DREG PORTA ' RA0..3
Define LCD_DBIT 0
Define LCD_RSREG PORTA ' RA6
Define LCD_RSBIT 6
Define LCD_EREG PORTA ' RA4
Define LCD_EBIT 4
Define LCD_BITS 4
TRISA = 0
TRISB = 0
CMCON = 7

Pause 1000 ' Wait for LCD to startup

duty VAR word ' Duty cycle value (CCPR3L:CCP3CON<5:4>)

TRISB.3 = 0 ' Set PORTB.5 (CCP3) to output
CCP1CON = %00001100 ' Set CCP3 to PWM
T2CON = %00000110 ' Turn on Timer2, Prescale=6

PR2 = 155 ' Set PR2 to get 1KHz out
duty = 125 ' Set duty cycle to 20%

loop:
SerIn SI,T9600,,# duty

if duty > 625 then
LCDOut $FE,1 ' Clear LCD screen
LCDOut "Duty to great" ' Display line 1
goto loop
endif

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

'duty = duty + 5 ' Increase duty cycle
LCDOut $FE,1 ' Clear LCD screen
LCDOut # duty ' Display line 1

GoTo loop ' Do it forever



Any other ideas?

Thanks,

Ben

[mister_e]

Try this one. I don't use LCD but echo the results to the PC.

@     __CONFIG  _HS_OSC & _MCLRE_ON  &  _LVP_OFF & _WDT_OFF & _PWRTE_ON  & _BODEN_ON  
DEFINE OSC 10

CMCON = 7
PORTA = 0
PORTB = 0
TRISA = 0
TRISB = %00000010

DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
DEFINE HSER_TXSTA 24h ' Enable transmit, BRGH = 1
DEFINE HSER_SPBRG 64  ' 9600 Baud @ 0.16%
DEFINE HSER_CLROERR 1 ' Clear overflow automatically

Duty    VAR WORD      ' Duty cycle value (CCPR1L:CCP1CON<5:4>)

CCP1CON = %00001100   ' PWM mode
T2CON = %00000110     ' Turn on Timer2, Prescale=1:16

PR2 = 155             ' Set PR2 to get 1KHz out
duty = 125            ' Set duty cycle to 20%
GOSUB ChangeDuty

Loop:
    HSerIn [DEC Duty]
    IF Duty > 625 THEN
       HSEROUT ["Duty too high... MAX = 625",13,10]
       ELSE
           GOSUB ChangeDuty
           HSEROUT ["Duty=",DEC Duty,13,10]
       ENDIF
    GOTO Loop
    
ChangeDuty:
    CCP1CON.4 = Duty.0 ' Store duty to registers as
    CCP1CON.5 = Duty.1 ' a 10-bit word
    CCPR1L = Duty >> 2
    RETURN

and read the FAQ about the fuse config... i think it's your main problem.

So far, it's working here.