Measurement

Why is this not working ccp capture mode

hi i have a program to measurement the period of my rc receiver , total period and , how long the hi puls stay high.

here my code : im use easypic 5 , cristal 4mhz , pic16f877a , microkbasic V5.01

i have also a another program but its works , and thats it , not safe thats why i thy this .

[code]

Program puls_meting_1

' Procedure for high-going pulse:
' 1. Configure CCP to capture on rising edge
' 2. Setup Timer1 so it will not overflow during max pulse width time
' 3. Enable ccp capture
' 4. Once capture flag bit is set, save captured value as T1
' 5. Reconfigure CCP to capture on falling edge
' 6. On 2nd capture, save 2nd value as PW
' 7. Subtract T1 from PW for the pulse width value

'DEFINE OSC 4

Symbol Capture = PIR1.2 ' CCP1 capture flag
Dim PULS1 as WORD ' totaal tijdt
Dim PULS2 as WORD ' totaal tijdt
Dim T1 as WORD ' 1st capture value
Dim PW as WORD ' 2nd capture value & ultimately final pulse width
Dim T1_HighByte as WORD ' 1st capture value
Dim T1_LowByte as WORD ' 1st capture value
Dim PW_HighByte as WORD ' 1st capture value
Dim PW_LowByte as WORD ' 1st capture value
Dim Text as string[10]
dim LCD_RS as sbit at RB4_bit
LCD_EN as sbit at RB5_bit
LCD_D4 as sbit at RB0_bit
LCD_D5 as sbit at RB1_bit
LCD_D6 as sbit at RB2_bit
LCD_D7 as sbit at RB3_bit

LCD_RS_Direction as sbit at TRISB4_bit
LCD_EN_Direction as sbit at TRISB5_bit
LCD_D4_Direction as sbit at TRISB0_bit
LCD_D5_Direction as sbit at TRISB1_bit
LCD_D6_Direction as sbit at TRISB2_bit
LCD_D7_Direction as sbit at TRISB3_bit

'===============================================================================
'-------- PROCEDURES --- PROCEDURES --- PROCEDURES --- declarations ------------
'===============================================================================
sub procedure Lcd_leeg

Lcd_Cmd(_LCD_CLEAR) ' Clear display
Lcd_Cmd(_LCD_CURSOR_OFF) ' Cursor off
end sub

main:



TRISC.2 = 1 ' CCP1 input pin (Capture input on 16f877a)
INTCON = 0 ' Interrupts off
CCP1CON = %00000101 ' Capture mode, capture on rising edge
T1CON = 0 ' TMR1 prescale=1, clock=Fosc/4, TMR1=off
TMR1H = 0 ' Clear high byte of TMR1 counter
TMR1L = 0 ' Clear low byte
T1CON.0 = 1 ' Turn TMR1 on here
Capture = 0 ' Clear capture int flag bit

While(1)

While Not Capture ' Wait here until capture on rising edge
Wend

' Rising edge detected / stuff 'captured' Timer1 value in T1
T1_HighByte = CCPR1H
T1_LowByte = CCPR1L
TMR1H = 0 ' Clear high byte of TMR1 counter
TMR1L = 0 ' Clear low byte

PULS2 = (T1_LowByte - T1_HighByte) ' High pulse width = PW-T1
CCP1CON.0 = 0 ' Configure capture for falling edge now
Capture = 0 ' Clear capture interrupt flag bit

While Not Capture ' Wait here until capture on falling edge
Wend

' Falling edge detected / stuff 'captured' Timer1 value in PW
PW_HighByte = CCPR1H
PW_LowByte = CCPR1L
TMR1H = 0 ' Clear high byte of TMR1 counter
TMR1L = 0 ' Clear low byte

PULS1 = (PW_LowByte - PW_HighByte)

Lcd_Init() ' Initialize Lcd

Lcd_leeg()
'Lcd_Out(1,1,"Puls MS")
'WordToStr (PULS,Text)
'Lcd_Out (1,8 ,Text)

Lcd_Out(1,1,"H/L")
WordToStr (PULS1,Text)
Lcd_Out (1,5 ,Text)
Lcd_Out(1,11,"-")
WordToStr (PULS2,Text)
Lcd_Out (1, 12,Text)

Lcd_Out(2,1,"H/L")
WordToStr (T1_HighByte,Text)
Lcd_Out (2,5 ,Text)
Lcd_Out(2,11,"-")
WordToStr (T1_LowByte,Text)
Lcd_Out (2, 12,Text)
Delay_ms(10)

Wend
END.
[/code]

thank you for your responce, marcel nijssen

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