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:
Code:
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
Bookmarks