program RF_Receiver

''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Serial byte reciever, checks RA0 for input.          '
' Sets coresponding input into an array                '
' array is decoded into corresponding output patteren. '
' Eirik Taylor                                         '
''''''''''''''''''''''''''''''''''''''''''''''''''''''''

dim sendbit as byte[8]
dim i, cnt as byte

main:
ANSEL = 0
ADCON0 = 0
TRISA = 1               ' pin 17 (RA0) as input
TRISB = 0
cnt = 0
sendbit[0] = 0
sendbit[1] = 0
sendbit[2] = 0
sendbit[3] = 0
sendbit[4] = 0
sendbit[5] = 0
sendbit[6] = 0
sendbit[7] = 0


' Initiate portb
portb = 255
delay_ms(10)
portb = 0
delay_ms(10)

gatherinput:
' look for possible startbit
do
loop until porta.0 = 1
cnt = 0
while porta.0 = 1                ' timer
 delay_us(20)                    ' effective delay works out to 27 µs
 Inc(cnt)
wend

if (cnt < 26) and (cnt > 18) then  ' startbit length around 22 cnts
  goto writesendbit
    else
    goto gatherinput
end if

writesendbit:

' save data stream into sendbit array
i = 0
for i = 0 to 7                          ' timer
do
loop until porta.0 = 1
cnt = 0
while porta.0 = 1
 delay_us(20)                           ' effective delay works out to 27 µs
 Inc(cnt)
wend

if (cnt <= 30) and (cnt > 20) then      ' Logic 1 around 17 cnts
   sendbit[i] = 1
   end if
if (cnt <= 20) and (cnt >= 9) then      ' Logic 0 around 11 cnts
   sendbit[i] = 0
   end if
next i

output:
' convert sendbit into output
i = 0
for i = 0 to 7
      if sendbit[i] = 1 then
         Setbit(portb, i)
         else
         ClearBit(portb, i)
      end if
    next i

goto gatherinput
end.