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program RF_Transmitter

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' RF byte transmitter, checks RA0 - RA3 and RB4 - RB7 for input.  '
' Sets coresponding input into an array                           '
' array is sendt serially to another PIC, which decodes bits.     '
' Eirik Taylor                                                    '
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

dim sendbit as byte[8]
dim i as byte

main:
TRISB = 110000     ' pins RB0 - RB3 as outputs, RB4 - RB7 as inputs
PORTB = 0

ANSEL = 0
ADCON0 = 0
TRISA.0 = 1
TRISA.1 = 1
TRISA.2 = 1
TRISA.3 = 1

gather_input:

' get input from RA0 - RA3 and RB4 - RB7 and put into byte array "sendbit"

' set bits according to input, porta
i = 0
for i = 0 to 3
      sendbit[i] = Testbit(porta, i)
next i
' set bits according to input, portb
i = 0
for i = 0 to 3
      sendbit[i+4] = Testbit(portb, (i+4))
next i
' result is 8 bit long byte with 1s and 0s symbolizing on or off.

output:
' transform sendbyte into serial data stream

' start bit to intiate transmission
    Setbit(portb,0)
    delay_us(600)
    Clearbit(portb,0)
    delay_us(300)

' convert sendbit into output pulse string
i = 0
for i = 0 to 7
Setbit(portb,0)
if (sendbit[i] = 1) then
   delay_us(600)             ' 450µs represents a 1
   else
  delay_us(300)              ' 300µs a 0
  end if
    Clearbit(portb,0)
  delay_us(400)              ' 300µs between every bit
next i

goto gather_input
end.