Ultrasonic [HC-SR04] + PIC16F877A

[intarapun]

help me Please

it code don't work

it's wrong

-----------------------------------------------------------
INCLUDE "modedefs.bas"
define osc 4
w var word
r var word
a var word
tr var PORTA.0 'Trig pin
ec var PORTA.1 ' Echo pin
TRISA = %00000010
TRISB = %00000000
PORTB = %00000000
w = 0
Main :
low tr
high tr
pauseus 10
low tr
pulsin ec,1,w
r = w/58
if r < 10 then
PORTB = %11111111
pause 200
endif
goto main
end
------------------------------------------

Sorry I bad eng

data sheet HC-SR04
https://www.google.co.th/url?sa=t&rc...55325884,d.bmk

[Sherbrook]

The PortA pins are analogue and you need to set them to digital with the ADCON1 register
ADCON1 = %00000110 - see datasheet

Or you could use PortB for trig and echo

Phil

[intarapun]

The PortA pins are analogue and you need to set them to digital with the ADCON1 register
ADCON1 = %00000110 - see datasheet

Or you could use PortB for trig and echo

Phil

thanks

but don't work

[LinkMTech]

You will also need to change your oscillator to a higher frequency for two reasons:
1. PAUSEUS min time is 24us at 4MHz
2. PULSIN resolution is 10us at 4MHz

I would suggest changing your crystal or resonator to 20MHz so PAUSEUS 10 will work and PULSIN resolution will be 2us.
Then try your modified code to see if it works:

PORTA = %00000000
TRISA = %00000010       ' Bit 1 set as input
PORTB = %00000000
TRISB = %00000000

ADCON0.0 = 0            ' A/D module disabled

define osc 20           
INCLUDE "modedefs.bas"

w var word
r var word
a var word
tr var PORTA.1 'Trig pin
ec var PORTA.2 ' Echo pin

w = 0
low tr

Main :
    high tr
    pauseus 10          ' Minimum 3us at 20MHz
    low tr
    pulsin ec,1,w
    r = w/29            ' Divide by 29, PULSIN resolution is 2us. 1 count every 2us        
    if r < 10 then
    PORTB = %11111111   ' Turn ON all PORTB outputs
    pause 200
    PORTB = %00000000   ' Turn OFF all PORTB outputs
    endif
goto main
end

[Sherbrook]

Have you set the configuration of the oscillator correct
See datasheet - Special features of the CPU

[Sherbrook]

This works on PIC16F873A so should work on PIC16F877A
Don't forget to pull MCLR high

@ DEVICE PIC16F873A, HS_OSC 'Xtal OSC
@ DEVICE PIC16F873A, WDT_OFF 'WDT off
@ DEVICE PIC16F873A, PWRT_ON 'Power-up timer on
@ DEVICE PIC16F873A, BOD_OFF 'Brown-out detect off

ADCON1 = %00000110 'All PORTA digital

define osc 4

TRISA = %00000010
TRISB = %00000000
PORTB = %00000000

w var word
r var word
a var word

tr var PORTA.0 'Trig pin
ec var PORTA.1 'Echo pin

PORTB = %11111111 'Flash LED on PORTB
pause 500 'to check PIC running
PORTB = %00000000

w = 0
low tr

Main :
high tr
pauseus 10
low tr
pulsin ec,1,w
r = w/58
if r < 10 then
PORTB = %11111111
else
PORTB = %00000000
endif
pause 200
goto main
end

[intarapun]

This works on PIC16F873A so should work on PIC16F877A
Don't forget to pull MCLR high

@ DEVICE PIC16F873A, HS_OSC 'Xtal OSC
@ DEVICE PIC16F873A, WDT_OFF 'WDT off
@ DEVICE PIC16F873A, PWRT_ON 'Power-up timer on
@ DEVICE PIC16F873A, BOD_OFF 'Brown-out detect off

ADCON1 = %00000110 'All PORTA digital

define osc 4

TRISA = %00000010
TRISB = %00000000
PORTB = %00000000

w var word
r var word
a var word

tr var PORTA.0 'Trig pin
ec var PORTA.1 'Echo pin

PORTB = %11111111 'Flash LED on PORTB
pause 500 'to check PIC running
PORTB = %00000000

w = 0
low tr

Main :
high tr
pauseus 10
low tr
pulsin ec,1,w
r = w/58
if r < 10 then
PORTB = %11111111
else
PORTB = %00000000
endif
pause 200
goto main
end

Oh!! Thanks IT work

But edit code r = w/58 >> r = ((w*10)/58)

Thank you very much Sherbrook & LinkMTech

[ligogeorge]

Try the following link, it might help you
Interfacing HC-SR04 Ultrasonic Sensor with PIC Microcontroller