RCTIME Equivalent on 20X2

[ayounis]

I needed an RCTIME-like routine to use with a QTR line detector. the standard PICAXE lib does not provide one. as the application in hand did care much about to the micro-sec timing but rather a time span, I had reached the following code. as I am working on a 20X2 device, this is where I have tested and verified things. I hope the following code is self explanatory.

; *******************************
; ******* RCTIME Routine  *******
; *******************************
;    Filename: QTR V2.bas		
;    Date: 14/04/2010 			
;    File Version: 2 	
;    Written by: Amr Younis 		
;    Function:		
;    Last Revision: RCTIME
;    Target PICAXE: 20x2	
; ******************************* 

#picaxe 20x2
#freq m8
#no_table
#no_data

hintsetup %00000100			'setup hw interrupts
setintflags %00000100, %00000100	'setup interrupt flags
settimer 65505				'setup timer at 32 usec

do
	high c.1 	      'start charging RC circuit
	pause 1	      'wait sometime to finish charging
	input c.1	      'toggle c.1 to input to start discharging the RC circuit
	timer = 0	      'reset timer var to 0
	pause 10	      'let the interrup finish and circuits are back to normal
loop

interrupt:
	if pinb.1 <> 0 then interrupt	'wait for a complete discharge, based on a TTL value
	w0 = timer  'capture rctime value
	toggle c.0  'inverse c.0, for demo purposes if you have a scope
	pause 10	'give c.0 some time
	flags = %00000000	 'reset flags
	setintflags %00000100, %00000100	'reinitiate interrupts
return

 

[BeanieBots]

I have no idea how the QTR line detector detector works but as you have been using RCTIME to measure it, I suspect it is analogue.
PICAXE chips can read analogue voltages directly with no need to resort to charging/discharging RC time constants.
Using ReadADC would be a much quicker/easier/more accurate solution if my assumption is correct about the sensor.

So, why do you want to emulate RCTIME besides that being the way the previous micro did it?

 

[BeanieBots]

[moved to active forum]

 

[ayounis]

thanks for your comment... I think you are confusing between reading voltage and time. the former will be done through ADC as you absolutely mentioned but the later will still need a time-based mechanism to measure, as I am advising.

 

[BeanieBots]

My sincere appologies.
I thought this was still under question.
[moved back to finished projects]