Beginner in need of help !!

[HenrikOlsson]

Hi Rob,
Welcome to the forum! As you can imaging there are several ways to do this (and most other things). Amoque shows you one, here's another (which also tries to take care of the debounce):

LED VAR GPIO.0
Switch VAR GPIO.1

ANSEL = 0                     ' No analog inputs
CMCON = 7                     ' Comparators disabled
TRISIO = %11111110            ' GPIO.0 as output

Main:
  IF Switch = 1 THEN          ' If the button is pressed...
    TOGGLE LED                ' ...we toggle the LED.
    Pause 20                  ' Then we wait for contact bounce on make to die, may need tweaking
    WHILE Switch = 1 : WEND   ' Then we wait for the user to actually release the button
    Pause 20                  ' Finally we wait for contact bounce on release to die, may need tweaking
  ENDIF
Goto Main

/Henrik.

[robbo78]

Hi Rob,
Welcome to the forum! As you can imaging there are several ways to do this (and most other things). Amoque shows you one, here's another (which also tries to take care of the debounce):

LED VAR GPIO.0
Switch VAR GPIO.1

ANSEL = 0                     ' No analog inputs
CMCON = 7                     ' Comparators disabled
TRISIO = %11111110            ' GPIO.0 as output

Main:
  IF Switch = 1 THEN          ' If the button is pressed...
    TOGGLE LED                ' ...we toggle the LED.
    Pause 20                  ' Then we wait for contact bounce on make to die, may need tweaking
    WHILE Switch = 1 : WEND   ' Then we wait for the user to actually release the button
    Pause 20                  ' Finally we wait for contact bounce on release to die, may need tweaking
  ENDIF
Goto Main

/Henrik.

Thanks for this Henrik, I found this the best way. Another question, what if I wanted to run a different command to just turning on the LED, what about if I wanted to start the LED flashing upon button tap? Could I do this with the same method?

Thanks,
Rob

[HenrikOlsson]

Hi,

> what if I wanted to run a different command to just turning on the LED
Don't understand this one, sorry...

> what about if I wanted to start the LED flashing upon button tap?
Well, yes. But as soon as you mention blinking it starts to get a Little bit more complicated. Why?
Because then you need delays in there, during which (if using PAUSE) the button won't be polled so it'll feel unresponsive. Of course there are ways around this but the correct one depends on what you want to do after we get that LED to blink....

Try this (I haven't, hope it works....):

LEDState VAR BYTE
Time VAR WORD

LED_OFF CON 0
LED_ON CON 1
LED_FLASH CON 2

Rate CON 250		      ' Time between LED toggles when blinking

Main:
  IF Switch = 1 THEN          ' If the button is pressed...
    LEDState = LEDState + 1
    IF LEDState = 3 THEN LEDState = 0
    Pause 20                  ' Then we wait for contact bounce on make to die, may need tweaking
    WHILE Switch = 1 : WEND   ' Then we wait for the user to actually release the button
    Pause 20                  ' Finally we wait for contact bounce on release to die, may need tweaking
  ENDIF

  IF (LEDState = LED_OFF) or (LEDState = LED_ON) THEN
    LED = LEDState            ' Turn LED on or off, solid.
  ENDIF

  IF LEDState = LED_FLASH THEN
    Time = Time + 1
    IF Time = Rate THEN
      TOGGLE LED
      Time = 0
    ENDIF
    PAUSEUS 1000
  ENDIF  
  
Goto Main

/Henrik.

[robbo78]

Update: Ive looked in the data sheet & found out the reason for dividing by either 24 or 32, if your working out low range then : 24, high range : 32. Thats another thing understood.

So the last thing I am struggling to understand now is, how do you get the number from th bits?

VR<3:0> = 1111 (15). < How on earth do you get 15 from just bits 1111?

This is the only thing that I'm struggling to understand now.

Thanks,
Rob

[richard]

the low range internal vref gives you 15 steps of 0.208 volt steps starting at 0v
the high range internal vref gives you 15 steps of 0.156 volt steps starting at 1.25v

if you don't need the cout as an actual physical output CM<2:0> = 110 is a better choice
and lets you chose pin 6 or 7 as your input (select with cmcon0.3 "CIS")
why waste pins on a 8 pin chip

0000=0
0001=1
0010=2
0011=3
...................etc etc
its called binary

[robbo78]

Edit: just re-read your post. I need to be able to read a pin & output on it at the same time (obviously with pauses, so do I need to use comparator with output?

Hi Richard, I just came back here from doing a bit of googleing. It took me about 2 mins to figure out that its just binary, maybe if I had paid more attention in Maths I would know this!

I now understand the voltage steps as well, everything is coming together now, its actually quite simple once understood.

I still need to know if you can use a comparator with internal reference on any pin or does it have to be the CIN- pin?

Cheers,
Rob

[richard]

if you don't need the cout as an actual physical output CM<2:0> = 110 is a better choice
and lets you chose pin 6 or 7 as your input (select with cmcon0.3 "CIS")

input to comparator is [ cin+ pin 7] or [cin- pin 6] with CM<2:0> = 110 its your choice

there are other modes but in all cases cin is only on pins 6,7

[richard]

if you need or can use the comparator output use CM<2:0> = 101
it still lets you chose pin 6 or 7 as your input (select with cmcon0.3 "CIS")

[robbo78]

Okay Richard thanks for your help.

So lets say I wanted an LED to be OFF if the voltage on cin+ is below 1.1v, & LED to be ON if the voltage is higher than 1.1v. Would I use this -

VR3 ... VR0 = 1000 (8) with a VDD of 3.3V the Vref will be (8/24) x 3.3 = 1.1V

I hope this is right lol

[richard]

there is not enough info to answer

what comparator mode ?
what cis setting
is vrr set
what cinv seting
how is led connected ?