a little help with keypad on 18f4520 please

[Dennis]

OKay I have even tried this example
http://www.rentron.com/serkey16.htm
and still get || on my lcd but the display does hange to things like ||| when I press some keys.

I really can't see where I am messing up ... please please could someone help me with this

[aratti]

Tray to use LCDout Dec Key_Press and see if you get the correct ascii value.

Al.

[Dennis]

Thanks Al

I now see numbers and not ||

OK so this is how I am now setup ...
http://www.rentron.com/serkey16.htm
notice there are no pull-ups on the rows.

I have series resistors on for the columns (100 OHM)
In other words KEYPAD >> RESISTOR >> PIC (PortB4-7)
Aah at least I am now seeing characters
When Idle the LCD just displays 4 8 12 and the 16 and then it repeats :-(
What's wrong :-(

My wishlist
A schematic( where to wire the pull-ups and where to wire the pull downs.
I would prefer not to use Port.B since I have the pickit 2 setup for ICSP on PortB.6 and B.7.
So which ports are advisable to use ? How should I TRIS each ?

Some code shows keypad ports as input tohers as output ... some show pull-ups others show no pull-ups ?

This is getting mega confusing

Should I just stick with dipswitches and give up on the dream of using a keypad for input ?

Any more help or comments would be seriously appreciated

[aratti]

OK so this is how I am now setup ...
http://www.rentron.com/serkey16.htm
notice there are no pull-ups on the rows.

You don't see any pullup because they are using internal pullup on portB

See the instruction that activate the weak pullup in the code.

OPTION_REG.7 = 0 ' Enable PORTB pull-ups

If you use different port then you have to use external resistors.

Al.

[Dennis]

Hi again Al

Thank you again for the reply :-)

Adding OPTION_REG.7 = 0 ' Enable PORTB pull-ups
Shows a compile error in Microstudio
Does not compile
I am using an 18F4520

So I am back to square one

Any suggestions

[Gusse]

INTCON2.7 = 0     'switch pull-ups ON

"Each of the PORTB pins has a weak internal pull-up. A single control bit can turn on all the pull-ups. This is performed by clearing bit, RBPU (INTCON2<7>). The weak pull-up is automatically turned off when the port pin is configured as an output. The pull-ups are disabled on a Power-on Reset."
(Page 96 on PIC18F4520 manual)

BR,
-Gusse-

[aratti]

Adding OPTION_REG.7 = 0 ' Enable PORTB pull-ups
Shows a compile error in Microstudio
Does not compile
I am using an 18F4520

Dennis not all pic has the internal pullup, could be that your mcu has not pullup.
(Check the datasheet).



Since you will need the pullups (otherwise the keypad will not work), so add four external 10K resistors.

Al.

Edit:

Gusse has read the datasheet for you: Replace OPTION_REG.7 = 0 with INTCON2.7 = 0

[Dennis]

Al, Gusse
Thank you both I implemented mister e's keypad using the whole of port B as an input had to perform some pin swaps on row and column order and it's working .
I have two more questions :

1.How do I set the keys to display the correct characters as per the keypad
my matrix key's are labeled is as follows:

1 2 3 A
4 5 6 B
7 8 9 C
* 0 # D

but when I press the keys for example 1,2,3,A
My readout is 1,2,3,4

Would I have to do a lookup or re-assignment ?

2. How do i capture a number ending with a hash for example

The reason I am asking is because I would like to type in a number for example 135 end it with a # to signify an enter and then store and send the number (TX).

Any further help would be appreciated