12F675 RS232 Help

[apl01]

Hi,

I am trying to connect a master and around 50 slaves using 12F675/12F510s with bidirectional communication. I2C looked like the perfect choice but since these chips are incapable RS232 looks like my next best option. I am very new to comms so I am trying to get basic programs to work like having two push buttons on the master one button switches on a led in the slave and the other button the other led. For some reason when i press either button both leds turn on.

Master code:

#include <12F675.h>
#device adc=8
#FUSES NOWDT, INTRC_IO, NOCPD, NOPROTECT, NOMCLR, NOPUT, NOBROWNOUT
#use delay(clock=4000000)
#use rs232(baud=9600,parity=N,xmit=PIN_A0,rcv=PIN_A1,bits=8)

A=0x10;
B=0x20;

Void main(){

While(1){
If(input(Button1))
PUTC(A); //if Button 1 is on send 0x10 to the slave

If(input(Button2))
PUTC(B); // if Button 2 is on send 0x20 to the slave
}
}

Slave code:

#include <12F675.h>
#device adc=8
#FUSES NOWDT, INTRC_IO, NOCPD, NOPROTECT, NOMCLR, NOPUT, NOBROWNOUT
#use delay(clock=4000000)
#use rs232(baud=9600,parity=N,xmit=PIN_A0,rcv=PIN_A1,bits=8)

Void main(){

While(1){
If(PUTC(A)=0x10)
Output_high(LED1); //0x10 is recieved turn LED1 on

If(PUTC(A)=0x20)
Output_high(LED2); //0x20 is recieved turn LED2 on

}

[RLScott]

[apl01]

Sorry, the correct code is:

#include <12F675.h>
#device adc=8
#FUSES NOWDT, INTRC_IO, NOCPD, NOPROTECT, NOMCLR, NOPUT, NOBROWNOUT
#use delay(clock=4000000)
#use rs232(baud=9600,parity=N,xmit=PIN_A0,rcv=PIN_A1,bits=8)

A=0x10;
B=0x20;

Void main(){

While(1){
If(input(Button1))
PUTC(A); //if Button 1 is on send 0x10 to the slave

If(input(Button2))
PUTC(B); // if Button 2 is on send 0x20 to the slave
}
}

Slave code:

#include <12F675.h>
#device adc=8
#FUSES NOWDT, INTRC_IO, NOCPD, NOPROTECT, NOMCLR, NOPUT, NOBROWNOUT
#use delay(clock=4000000)
#use rs232(baud=9600,parity=N,xmit=PIN_A0,rcv=PIN_A1,bits=8)

Void main(){

While(1){
If(GETC(A)=0x10)
Output_high(LED1); //0x10 is recieved turn LED1 on

If(GETC(A)=0x20)
Output_high(LED2); //0x20 is recieved turn LED2 on

}

I have tried using equal to (==) but still no luck.

[apl01]

GETC() not GETC(A) i sorry i cant type

[ckielstra]

When posting source code, please use the 'code' buttons to preserve the layout of your code. This makes for much easier reading.

[apl01]

Yes i know sorry but my code is not accessible at the moment. Ok what you say about getc() makes sense i will give that a try thanks.

[apl01]

I tried the code you suggested below but with still no luck, when using RxChar = 0x10 switching either pushbutton will switch on both LEDs when using RxChar == 0x10 Both LEDs flicker when either button is pressed. Strange.

Slave code:

#include <12F675.h>
#device adc=8
#FUSES NOWDT, INTRC_IO, NOCPD, NOPROTECT, NOMCLR, NOPUT, NOBROWNOUT
#use delay(clock=4000000)
#use rs232(baud=9600,parity=N,xmit=PIN_A0,rcv=PIN_A1,bits=8)

void main()
{
int8 RxChar;

while(1)
{
RxChar = getc();

if (RxChar==0x10)
output_high(LED1); //0x10 is received turn LED1 on

if (RxChar==0x20)
output_high(LED2); //0x20 is received turn LED2 on
}
}

}

[PCM programmer]

You can split these boards into two separate projects and trouble-shoot
them one at a time, by using a PC.

1. Add a MAX232-type chip to each board. Connect the MAX232 to the
PIC Tx and Rx pins, and to the PC's serial port.

2. Change the commands to visible ASCII characters, such as '1' and '2'.
(Note the single quotes). Edit your code to use these commands.

3. Connect the transmitter PIC board to the PIC. Press your push-
button switches and watch if the proper commands are sent to the PC.
You should see 1 or 2 displayed on the PC's terminal window (HyperTerm).

4. Disconnect the transmitter board. Set it aside. Now connect the
receiver board to the PC. Type commands into the Hyperterminal
window. (ie., type 1 or 2). Watch if the LEDs on the receiver board
turn on/off properly.

5. When both boards work correctly with the PC, you can connect them
together. You can leave the MAX232 chips in place, or you could
remove them at this time, and use a direct connection. Now test
both boards together. If the wiring is correct, they should work.

[apl01]

Yes thats a very good idea thanks but i dont have rs232 on my laptop is there a different chip i could use or convertor etc?

[PCM programmer]

You could get a USB to serial adapter cable. Plug the USB end
into your Laptop, and plug the RS232 end into your board. (with MAX232
added to your board).
Example:
http://www.siig.com/ViewProduct.aspx?pn=JU-CB1S12-S3

[apl01]

Ok great thanks ill give it a shot.

[apl01]

I tried connecting up the PIC to the computers rs232 port and have been having difficulties getting it to work.

First off the circuit diagram from the max232 is slightly different to that of the CCS compiler manual pg 276 (caps are back to front) i have gone with the max232 schematic. I have used an old rs232 cable where i have established (i think) Red is Rx, Green is Tx and Black is GND. I have connected this through a rs232 to usb converter.

In the CCS serial port monitor i have 1 stop bit, the software flow control is Both with no hardware flow control items selected.I am not to sure if i need to use DTR and DTS so i have un-selected them. I am trying to send a hex value of 10 from the serial port monitor to the PIC and for the PIC to respond by turning a LED on the code is:

[PCM programmer]

1. Use a lower baud rate, such as 9600 on both the PIC and the PC.

2. Don't use any flow control, hardware or software.

3. Make sure the connections between the MAX232 and the PC are
correct.

4. Change the command character to one that can easily be typed
from a terminal. Instead of 0x10, change it to '1' (0x31).
Note the single quotes. Those are necessary. Then you can
just type the 1 key and it will send the character. Example:

[apl01]

My compiler version is 4.057
I still cant send data to turn on the LED but i can recieve data from the PIC to the PC with the program below but garbage appears on the termianl rather than Hello World?

[ckielstra]

Just to make sure: how is the connection from PIC to your PC? Have you added a required voltage level converter like the MAX232?