'LEDNAP.BAS program for September "Silicon Chip" Picaxe-08 article. Ver 1.0 12/7/03
'Potentiometer acts as multi position switch!  Stan. SWAN  => s.t.swan@massey.ac.nz
'Values as set here allow 7 different flash types to be dialled up via the 500k pot
'Much tweaking still possible-better reading b0 ranges,alter pot(Log?),R value etc
'White LED (10mm ?) via BC547 with 470 Ohms from its base to Picaxe pin 2 via "NAP".
'Actual nap value depends on application - steady light,standby, rescue beacon etc
'Even nap 0 has distinctive ~20 Hz flicker = ideal bike front for attention getting?
'NB ~10Hz flicker is most irritating to many observers - may cause epileptic fit?!
'On 3AA 4.5V supply & 470 base R,typical DSE Lux meter values (pulsed of course) ~
'nap 0=35mA 340 Lux,   nap 1=22mA 216 Lux,  nap 2= 13mA 120 Lux,  nap 3= 8mA 70 Lux
'nap duration = 2^period x ~18ms , with period values 0-7 ( rolled over if beyond )
'nap 0 ~18ms,  nap 1 ~36ms,  nap 2 ~72ms,  nap 3 ~144ms,  nap 7 ~ 2secs
'Inbuilt loop o'head of course distorts M/S ratio. Red LED direct driven from pin 4 
'Program download from => www.picaxe.orcon.net.nz/lednap.bas  Comments (') optional 
'--------------------------------------------------------------------------------
ledflash:			'main adc read to set nap time or dim with pwm etc 
readadc 1,b0 			'ADC read pin1 -via 500k pot(Log?) & 47k  V.divider 
b1= b0/22			'divide returned "nap" value so fits in  0-7 range
if b1=0 then redflash		'"08" readadc values are in 16 blocks 0-160,11 wide
if b1=1 then redpwm		'Could use as is,but division OK for just 7 values
if b1=7 then beacon		'1/2 Hz beacon mode nap 7 forced via  b2 variable 
'---------------------------------------------------------------------------------
whiteflash:			'routine for normal adjustable white flash rates 
   b2=b1-2			'tweak returned b1 rates,since too short as divided 	
       high 2:pause 10:low 2  	'LED pulse - somewhat overdriving via transistor
   nap b2 			'brief snooze to allow LED/BC547 cool down ! 
goto ledflash 			'return to main pot. reading procedure
'---------------------------------------------------------------------------------
redflash:			'red led at pin 4 flash - rear bike light style
 high 4:pause 10:low 4:nap 7	'pulsed ~ every 2 seconds - adjust to suit needs 
goto ledflash			'return to main pot. reading procedure
'---------------------------------------------------------------------------------
redpwm:				'red led attractive pulsing effect
 for b3=0 to 255 step 2		'loop so red LED has pleasing brightness increase 
   pwm 4,b3,1 :next b3		'PWM pin 4 LED one cycle at increasing pulse width
     for b3=255 to 0 step -2	'loop to fade led out
   pwm 4,b3,1			'PWM pin 2 led one cycle at decreasing pulse width
 next b3:pause 300		'led displays a pleasing "heartbeat" effect !
goto ledflash			'return to main pot. reading procedure
'---------------------------------------------------------------------------------
beacon:				'battery life prolonging (weeks ?) beacon flash
       high 2:pause 10:low 2  	'brief led pulse - via transistor.Approx 1mA draw
nap 7 				'~ 2 sec delay between pulses
goto ledflash 			'return to main pot. reading procedure