PIC Communication

C

cne

New Member

• Oct 8, 2010

• #1

Hello,

I have been working on a PIC controlled scoreboard recently. It will consist of a controller console at one end, and a large display at the other.

Both the controller and the display will contain a PIC. The controller PIC will send signals to the display.

My question is, which method of communication should I use to interconnect the two PIC's.

Some important aspects are:
-Data needs to be sent over a long cable
-Needs to use as few wires as possible

I am fairly new to microcontrollers so my coding knowledge is limited.

Thanks in advance,

Cameron

 

Mike_2545

Super Moderator

• Oct 8, 2010

• #2

You could use wireless serial communication with a device on each end called X-Bee found here **broken link removed**

 

blueroomelectronics

Well-Known Member

• Oct 8, 2010

• #3

RS485 is long range.

 

K

kjennejohn

New Member

• Oct 9, 2010

• #4

RS485 is probably the best answer. It's quick and simple to implement. You just feed your TTL serial into a MAX485 IC or LTC1481 IC, then through up to a thousand feet of two copper wires to another IC as mentioned at the other end to get TTL out. If you use the direction control pins on the ICs mentioned, you can do bi-directional communications, but only one PIC can talk at a time. Plan on having a 100 Ohm or 120 Ohm termination, quarter-Watt (can be 5%) resistor at both ends.
Hope that helped.
kenjj

 

Noggin

Member

• Oct 10, 2010

• #5

Or do full-duplex and don't worry about direction control pins. Makes life easy, but adds 2 wires. X-Bee is simple though and you won't need wires.

 

C

cne

New Member

• Oct 10, 2010

• #6

through up to a thousand feet of two copper wires to another IC as mentioned

Click to expand...

So I can communicate both ways, using two wires, just not at the same time?

 

Noggin

Member

• Oct 10, 2010

• #7

cne said:

So I can communicate both ways, using two wires, just not at the same time?

Click to expand...

Three wires if you count the ground, but yes.

 

C

cne

New Member

• Oct 11, 2010

• #8

So would this be correct?

 

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Noggin

Member

• Oct 11, 2010

• #9

That's close. You need to tie RE and DE to a pin. They can both go to the same pin. /RE is a Receive Enable pin and DE is a Driver (output) Enable pin. Set /RE and DE low when you expect to receive data and set /RE and DE high when you want to transmit data.

And don't forget to actually connect power and ground to the pins, and your ICSP header too.

 

Last edited: Oct 11, 2010

C

cne

New Member

• Oct 11, 2010

• #10

Is the code for RS485 the same as RS232. I am using flowcode, which has the RS232 component, but no RS485.

 

gramo

New Member

• Oct 12, 2010

• #11

Basically, with RS485 it's just the hardware interface that changes. From there you can drive the RS485 devices with UART/RS232 whatever they are rated for.