[PIC] PIC18f452 to PIC18f452 Communication

[Aragant]

I am doing a project in which one PIC18f452 is connected to sensors, while second is with LCD i want to send data to from one PIC18f452 to other.
I am using full-duplex mode. Attached is the image of the working circuit.

I want to know that how long I'll able to send this data?
In other words what could be the maximum length of the cable between two PIC18f452?

 

[paulfjujo]

hello,

add some details as :
how long is the distance between the 2 PIC ?
What is the UART speed ?
quality of cable ?

 

[Aragant]

hello,

add some details as :
how long is the distance between the 2 PIC ?
What is the UART speed ?
quality of cable ?

Hi..
At-least 20 meters.
baud rate = 9600.
2-Wire.

- - - Updated - - -

If i put Max232 in the circuit the values on the same same code are not right.

 

[paulfjujo]

hello
2-Wire. ? + 0V => 3 wires

you must use 2 max232 !
with RS232 level on PIC input you can destroy it !

PIC1 TTL level <->--///--- Max232 <-///-- RS232 levels --///- 20 meters---///---- Max232 --///-- <-> TTL level PIC2

 

[jayanth.devarayanadurga]

Make it wireless bu using 2 XBees. You don't need MAX232 if you use XBees. You can also try I2C and wireless communication using nRF24L01+.

 

[Aragant]

thanks paulfjujo

I only used 2 MAX232 and the result is fine...

I am fresh in embedded systems but this looks ok to me what do you say?

I only need PIC1 talking to PIC2 (it should be TTL level for that)

 

[paulfjujo]

If no noisy environment, you can try direct connection TTL level
put a pull up resistor of 1Kohms on receiver side .

better could be to insert some buffer in the path
like trigger buffer 74HC14 ( 2 in serial to don't reverse the level).

What about galvanic insulation ?
is there a risk of diffrence of potential between the 0V of each module ?

 

[pasicr]

Aragant,
look this post
https://www.edaboard.com/threads/294357/
that is I2C master / slave project, working (tested) model with 16F887,
maybe you will find something usefull,
BR