bitbang_IR.bas test for bitbang bitstream

option default none
option explicit

const carrier% = int(1e6/40e3)                '40kHz period time in us
const phase% = int(carrier%/2)                'half the carrier period time
const bits% = 6                               'number of bits to send


'generate an array that contains the 40 time delays  '40 transitions in data pulse

dim i%,keycode%
dim a$
dim puls%(39):for i%=0 to 39:puls%(i%)=phase%:next i%


'setup ---------------------------------------------------------------------------------------

'Init GP0 as the transmit pin, and force low (IR LED off)
setpin gp0,dout : pin(gp0)=0

'Init GP1 for interrupt low (IR receiver modules are default high, low when IR detected)
setpin gp1,intl,IR_in


'main ----------------------------------------------------------------------------------------

keycode% = 38 'hardcoded the value for "forward"
send_IR

'Interrupt ------------------------------------------------------------------------------------
sub IR_in
'do nothing yet
end sub


'subroutines ----------------------------------------------------------------------------------

'send keycode% using carrier bursts coded in puls%()
sub send_IR

local i%

for i%=bits%-1 to 0 step -1          'cycle through the 6 bits in reverse order
  bitbang bitstream gp0,40,puls%()   'leading pulse
  pause 1.2                          '2ms - 0.5ms carrier - 0.3ms MMBasic loop delay
  if (keycode% and 2^i%) then pause 2   'when 1 bit then wait 2ms more until next
next i%

bitbang bitstream gp0,40,puls%()      'terminating pulse
pause 50                              'interword gap (pause until next keycode sent)

end sub