help with pic's 1

[sixtoedsloth]

Hi,

i decided to get into pic programming as i need to do some interfacing with a pc. i got a book and the picstart plus
programmer. now with the exception of the 16F84 every chip i read about is discontinued when i go to the store.

i want (i think) a pic with a uart, and a simple program to send recieve chars to the pc. ie:

when a 4 digit code is pressed on a keybpad i want the code to be sent to the pc. the pc will then perform some action dependimg on which code is recieved, then sends back a reciept char to the pic which can then display a value on an lcd display.

i thought of starting small and getting the pc bit working
then adding the keypad and then the lcd.

is that a good idea?

all help appreciated.

Cheers,

Russ

 

[cbarn24050]

Hi, its usually easier to do it the other way round. LCD first, then the keypad, and finally the uplink to the pc.

 

[pebe]

At the outset, you need to plan what you are going to do before you decide on a chip. Otherwise you may suddenly find you have run out of I/O pins and you'll have to start again.

Start with a block diagram. How are you going to drive the LCD? Direct from the PIC or with an LCD driver? How many I/Os does it need?

You only need to send and receive data to the PC one byte at a time. So do you really need a UART? You can generate a serial stream in the PIC and pass it to the PC with just a transistor. You can pass the reply back with just a resistor. That only needs two pins. But you will need a chip with a timer interrupt.

Are you going to scan the keypad by wiring it as a matrix? That would save I/Os.

When you have got the answers you will be in a position to 'pick a PIC' and start programming - a section at a time.

 

[JigaWatt]

Have you been to

http://www.piclist.com

yet? Lots of info there, and a very valuable & highly active mailing list. There are a lot of PIC experienced people there.

HTH!