rem AsciiKeyboard.bas
symbol sclk = 7		' clock (output pin)
symbol serdata = input6	' data pin
symbol counter = b7	' variable used during loop
symbol var_in = b5	' data variable used durig shiftin
symbol bits = 8		' number of bits
symbol MSBValue = 128	' MSB value
symbol DisplayHex = bit0  '

init:
high Sclk
DisplayHex = 0
main:
high 0
high 2
if input7 = 1 then getkeystroke  'Flag is set by the keyboard strobe
goto main
getkeystroke:
low 2
gosub shiftin_LSB_Pre		'The clock also resets the flag
high 2
serout 1,T2400,(var_in)
if var_in = $d1 then SetHexFlag
if var_in = $d0 then ClearHexFlag
if DisplayHex = 0 then main
DisplayHexValue:
serout 1,T2400,(40)
b1 = var_in & $F0
b1 = b1 / 16
gosub writehex
b1 = var_in & $0F
gosub writehex
serout 1,T2400,(41," ")
goto main

SetHexFlag:
DisplayHex = 1
goto DisplayHexValue

ClearHexFlag:
DisplayHex = 0
goto main

' ***** Shiftin LSB first, Data Pre-Clock *****
' Shift in the data LSB first into variable var_in 
' Read data before sending clock pulse 
' Using clock output pin sclk
' Using data input pin serdata 

shiftin_LSB_Pre:
	let var_in = 0
	for counter = 1 to bits			' number of bits
		var_in = var_in / 2 		' shift right as LSB first	
		if serdata = 0 then skipLSBPre
		var_in = var_in + MSBValue	' set MSB bit if serdata = 1
skipLSBPre:
		pulsout sclk,4 			' pulse clock to get next data bit
	next counter
	return
	
writehex:
if b1 < 10 then number
b1 = b1 + "W"
goto writeit
number:
b1 = b1 + "0"
writeit:
serout 1,T2400,(b1)
return