reaction timer - multiplex inputs

Pommie · May 30, 2011

You need to type [code] and [/code] around your code to keep the formatting.

Mike.

cybersky · May 30, 2011

Code:

Dim i As Byte
Dim rtim As Word  'number of cycles
Dim mtim As Word  'max time allowed (in cycles)
Dim react(10) As Word  'array to hold reaction times

'new variables from the forum example
Dim ms As Word
Dim seconds As Word

i = 0
main:  'i will have to restart the pic to reset - fine for now
If PORTB.0 = 1 Then
	Goto ledon  'simplified version of final app - using 1 led and 1 button
Endif  'just want this timing issue sorted please.

If PORTB.1 = 1 Then
	Goto getnewframes
Endif
Goto main
	
ledon:
	PORTA.1 = 1  'led on

getkey:
If PORTB.2 = 1 Then  'reaction button
	PORTA.1 = 0  'turn out the light...
	rtim = ms
	react(i) = ms  'save reaction into array
	i = i + 1
'WaitMs(3000)  'wait 3sec before led on
Goto ledon  'start led on again and get another timing
Endif
If PIR1.TMR2IF = 1 Then
	PIR1.TMR2IF = 0
	ms = ms + 1
		If ms = 1000 Then
			ms = 0
			seconds = seconds + 1
		Endif
Endif
If ms > 2 Then  'no key pressed yet so we goto next
	PORTA.1 = 0  'turn out the light
'WaitMs(3000)
	Goto ledon
	i = i + 1
Endif
Goto getkey
getnewframes:
'serial data from pc - code not needed
'when done we start ledon

Here is my understanding of the code fragment using timer / interrupt.

When i try to simulate this it hangs at ms = ms + 1.
I thought timer / interrupt needed the interupt pin to chg state in order to register an "interupt" ??

cybersky · May 30, 2011

Hi I think i have a solution - but could you clarify the interupt timing count w.r.t my version of the code ? ie what would ms = 2 be in realtime?

Code:

TRISB = 0x00  'set all PORTB pins as outputs
Config PORTB = Input
INTCON.T0IE = 1  'enable Timer0 interrupts
INTCON.GIE = True  'enable all un-masked interrupts
OPTION_REG.T0CS = False  'set Timer0 clock source to internal instruction cycle clock
Dim i As Byte
Dim rtim As Word  'number of cycles
Dim react(10) As Word  'array to hold reaction times
Dim ms As Word
Dim seconds As Word

i = 0
main:  'i will have to restart the pic to reset - fine for now
If PORTB.0 = 1 Then
	Goto ledon  'simplified version of final app - using 1 led and 1 button
Endif  'just want this timing issue sorted please.

If PORTB.1 = 1 Then
	Goto getnewframes
Endif
Goto main
	
ledon:
	PORTA.1 = 1  'led on

getkey:
If PORTB.2 = 1 Then  'reaction button
	PORTA.1 = 0  'turn out the light...
	rtim = ms
	react(i) = ms  'save reaction into array
	i = i + 1
'WaitMs(3000)  'wait 3sec before led on
Goto ledon  'start led on again and get another timing
Endif
If ms > 2 Then  'no key pressed yet so we goto next
	PORTA.1 = 0
	ms = 0  'turn out the light
'WaitMs(3000)
	i = i + 1
	Goto ledon
Endif
Goto getkey
getnewframes:  'serial data from pc - code not needed
End                                               
On Interrupt  'interrupt routine
ms = ms + 1  'decrement the value on PORTB
INTCON.T0IF = 0  'enable new TMR0 interrupts
Resume

Interupt is almost like an independent thread? sort of?
so when it fires i add 1 to ms but what does this represent ?

ericgibbs · May 30, 2011

hi,
Aquick run thru of your code on Oshonsoft,
Add the 'AllDigital' statement and make PORTA an output in order to drive the LED.

The program detects PORTB.0 ok, but checks PORTB.1 intermittently.
The ISR is being called OK.
For Simulation, add Define SIMULATION_WAITMS_VALUE = 1

cybersky · May 30, 2011

thanks for checking the code - however would the value in ms = mseconds? based on 4mhz?

ericgibbs · May 30, 2011

cybersky said:
thanks for checking the code - however would the value in ms = mseconds? based on 4mhz?

I didn't check that out yet, you can get a good idea of the time period by using the 'Real Time Duration & Clock cycles' on the IDE window.

Or set up the IDE oscilloscope and directly measure any delays. OK.

EDIT:
For testing varying delay periods, why dont you set adc0 as an analog input, connect a 10Kpot from +5V and 0V, wiper to the adc input pin.

Use the pot to vary the test delay period [ use the 10bit adc value] and find the best delay for the project response.

Do you follow OK.?

cybersky · May 30, 2011

Hi

basically we will be varying the delays from a software pattern sort of test. So i will be sendng the pic the ondelay value and the delay between led on's. then a string representing the "sequence" of led to flash.
So we have 36 leds with 36 switches in a multiplex setup and measuring the response per "led" based on the max reaction time. we using a pic16f874A - It is for a thesis project (not mine, just helping with the dev/building of rig)

thanks for the response. I have just wrapped my mind around the timer thing - but the adc will follow soon coz i want to build a temp sensor (which has been done to death - but i want my own and in basic ! LOL).

ericgibbs · May 31, 2011

cybersky said:
Hi
- but the adc will follow soon coz i want to build a temp sensor (which has been done to death - but i want my own and in basic ! LOL).

hi,
This link will help with the adc debugging in OSH.
https://www.electro-tech-online.com...oft-simulator-16fanalog3-external-module.html

cybersky · Jun 2, 2011

thanks for the link.
just noticed something in the sim, can i "use" the timer/interupt pin? or should it be left open? Using the Pic 16f874A.

ericgibbs · Jun 2, 2011

cybersky said:
thanks for the link.
just noticed something in the sim, can i "use" the timer/interupt pin? or should it be left open? Using the Pic 16f874A.

hi,
You could leave it open, or you could toggle it by clicking on the 'T' on the microview.

I use this external module for 'pulsing' input pins, give it a try.

cybersky · Jun 2, 2011

thanks - but in general is it ok to use the timer pins?
and
INTCON.T0IE = 1 'enable Timer0 interrupts
Then
INTCON.T0IE = 2 'enable Timer1 interrupts ?? if pic has more than one?

ericgibbs · Jun 2, 2011

cybersky said:
thanks - but in general is it ok to use the timer pins?
and
INTCON.T0IE = 1 'enable Timer0 interrupts
Then
INTCON.T0IE = 2 'enable Timer1 interrupts ?? if pic has more than one?

Yes, providing you test for the source of the interrupt, ie: tmro0 or tmr1

cybersky · Jun 2, 2011

as i understand it... the timer function will fire "automatically". If i use the timer pin as an input and it is triggered would that not also cause the timer function to fire aswell ?? sorry for the "simple" question, but i would rather ask.
could you pls show a sml piece of code for somthing like: on interrupt 1 , on interrupt 2 ?

ericgibbs · Jun 2, 2011

cybersky said:
as i understand it... the timer function will fire "automatically". If i use the timer pin as an input and it is triggered would that not also cause the timer function to fire aswell ?? sorry for the "simple" question, but i would rather ask.
could you pls show a sml piece of code for somthing like: on interrupt 1 , on interrupt 2 ?

You can preload the Timer counters and count DOWN to cause an interrupt at 0000 > FFFF

cybersky · Jun 2, 2011

hi
do you perhaps have some documentation on the INTCON ?
INTE = 1 'rb0 pin will trigger interrupt
INTCON.TOIE = 1 'enable the interrupt to fire based on timer

OPTION_REG.T0CS = False 'set Timer0 clock source to internal instruction cycle clock
so
OPTION_REG.T"1"CS = False 'set "Timer1" clock source to internal instruction cycle clock ?

how do you use the TMR0 Prescalers ?
with the lack of literature on Oshonsoft, small code bits are a real help.

cybersky · Jun 2, 2011

repeat after me : "Google is your friend...", heheh
I guess my input to oshonsoft would be to help us "lazy" programmers by providing an intellisense feature so that we can check what other attributes there are to functions and SFR's.

ericgibbs · Jun 2, 2011

cybersky said:
repeat after me : "Google is your friend...", heheh
I guess my input to oshonsoft would be to help us "lazy" programmers by providing an intellisense feature so that we can check what other attributes there are to functions and SFR's.

hi,
All the INTCON and SFR's are covered in the PIC's datasheets, do you have a copy of the 16F874A sheet.?

I could post some code fragments for the Timers, what exactly are you wanting to do with them.???

I know its a reaction timer, but how are the switches , displays etc, connected to the PIC.????

cybersky · Jun 2, 2011

we have them multiplexed - 6rows on RB with 6cols on RA then a mix of RC & RD for the switch inputs.
the code samples are just for information sake and to increase my "oshonsoft" knowledge base. - I have downloaded all the datasheets and some tutorials on the SFR and Timers. Perhaps I am needing the "syntax" for oshonsoft more than perhaps the code, but sample do help. if i could ref. multiple timers the possiblities...

ericgibbs · Jun 2, 2011

hi,
I guess you have the OSH Basic manual for the 16F series of PIC's.?

I will try to put together a couple of demo programs, I am busy at the moment, so it could take a couple of days.

cybersky · Jun 2, 2011

yes i have read the oshonsoft manual but it makes you want to flip the monitor around to see where the "missing" pages are ! LOL.
I have made headway using the datasheets and OSH. timer 1 and timer 2 .
BUT looking forward to your pearls of code - don't mind the wait just very happy that you were able to assist! thank you.

reaction timer - multiplex inputs

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