LCD and keypad interface using PIC16f84

[f17]

16f84 keypad

Hi,

I'm a student and I'm graduating this school year. And for our final project, we need to create two wireless messengers that could communicate to each other. Could there be anyone who could help us with this? I would just like to ask if you might know of a site or of a schematic/code that could help us in interfacing our 20x4 lcd with a 4x4 keypad using PIC16f84? We are still thinking if we should buy the keypad or make our own.

Any help would be greatly appreciated.

 

[Slayerza]

pic16f84a lcd

Hi,
I think it would be better to buy the keypad if you can find one to suit you purposes. If you need special characters on the buttons, building your own is better.

As far as the interfacing goes, you have several options. But it depends on what you need. If speed is not much of a concern (usaully not with LCDs) you can run the screen in 4bit mode (nibble). This saves 4 IO lines but makes the code more complex.

Secondly, since the screen latches the data you could multiplex the keypad and the screen and save some more IO lines.

This is usually a simple process. If you need some more help please ask.

Cheers
Slayer

 

[f17]

pic16f84 lcd

Hi,

Thank you for the idea.

We really need to save IO lines since we also have to interface the RF TX/RX plus the SRAM with the PIC. We need to store more than 5 messages to the device. Do you think this is possible just by using one PIC?

We also saw a 2-wire lcd interface. We are trying to get more ideas on how to save IO pins. We'll try multiplexing also. I would appreciate more suggestions.

Anyway, thanks again.

 

[robert040]

pic keypad lcd

The PIC16F84 is not so eazy to get; it is obsolete for quite some while; the F628 is a more or less direct replacement. It is also in a DIP18 package.
For the two-wire LCD you need an shift register and some passive components; you could do the same for the keyboad.
But why not use a larger PIC such as a 28-pin F876 or a 40-pin F877. They are very popular and widely available. With the extra IO pins you can do without external logic.
How much data do you want to store in external SRAM? Can't it be done in internal RAM or in eeprom? You could think of serial RAM or EEPROM.

 

[Slayerza]

pic lcd keypad

I agree, the PIC is obsolete, it makes sense to use a newer larger PIC as the increased cost wil be much less than the extra logic, passives, design time, and PCB cost.

Using a larger PIC might also enable you to use the integrated EEPROM and thus reduce the design complexity.

Cheers
Slayer

 

[f17]

lcd 16f84

hi there!

I think I agree with what you say. We've been thinking about using other type of PIC. There are lots of advantages. But we are also considering the availability of the product in our area. (It would take weeks to obtain the product if we should order from elsewhere and we haven't got much time) That's why we are stuck with the 16f84 since it is readily available here. (I don't even understand why)

Anyway, I believe we need to store more than 9.6kb. We also need to do some scrolling.

By the way, thanks for the suggestion

 

[Slayerza]

keypad lcd pic

Hi,
If you can only get 84s then I suppose you'll have to make do. It can still be done with more than one PIC even more (although this would make a less elegant design) Sometimes the availability of parts plays a major role in the design process.

Cheers
Slayer

 

[pepek]

keypad interfacing with pic pic 16f84

look this...
**broken link removed**

 

[snb7aug]

16f84+lcd

thak you very much

 

[mutlu_sgul]

lcd and keypad pic basic

It's very simple to construct pic circuits. Try PicBasic to create simpler codes.

 

[mongoose]

pic16f84 interfacing

Hi,

If you are looking for the code I can send you it because I have tried it

 

[ankur_rustagi12]

keypad application in pic16f84a

Can u plz send the code to ankur.rustagi12@gmail.com

i m suing pic16f877a and interfacing 20x4lcd+ 4x4 keypad
the project wud b like simple menu based sytem..
a menu will apear on tyhe lcd screen and user selcets a option from the menu.
thats it.

plz send it asap..as it is my final yr project and i have only 1 week eft to complete it.

if u have circuit to..then do send it ..plz...
thank you..

 

[saikarthik]

hi i am too doing a similar project can anyone send me the code for interfacing a 20χ4 lcd and 4χ4 keyboard with pic 16f877