RS232 HELP- using Hyperterminal

[Sophi]

Here's my code (below) for a simple communication with Hyperterminal. I don't see anything (scope) on the receive line (C7) but do see action on C6 when I remove the lines:
C = getch();
putc('y');
Can someone help me with a communication example? - I am totally new to this so perhaps I have hyperterminal configured wrong as well?
Thanks-
Sophi

My settings:
connected Direct to Com 2
bits per second- 9600
data bits- 8
parity- none
flow control- none (I find I can't type to the screen without this setting)
IN ADVANCED- I unchecked FIFO buffer
IN ASCII setup- checked echo typed characters locally and wrap lines

My code:
#include <16c74a.H>
#device ICD=TRUE
#fuses HS,NOPROTECT,NOWDT,NOBROWNOUT,PUT
#use delay(clock=20000000) // adjust for resonator frequency
#include <LCD2_877A.c>
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#include <stdio.h>

main()
{

init:
lcd_init();
lcd_putc("\fWELCOME\n"); // welcome
delay_ms (1000); // wait for amps & a/d to stabilize
output_low (PIN_A0); // turn LED off
delay_ms(2000);
setup_adc_ports(NO_ANALOGS); // sets port A all digital
setup_adc( ADC_OFF ); // no analog
output_high (PIN_A0); // LED on
delay_ms (250);

while(1) // while true
{
int C;
putc('h');
output_high (PIN_A0); // LED on
C = getch();
putc('y');
delay_ms (1);
output_low (PIN_A0); // LED off
delay_ms (1);
}
} //end main

[Humberto]

[Sophi]

Thanks Humberto-
Yes I read everything in the forum - that's how I chose all my settings for Hyperterminal!
I am using a Protoboard (Olimex) that comes with a MAX232 chip. I've connected TX from the MAX232 to PIC- C6 and RX from MAX232 to PIC C7. I'm using a PIC16C74A.
Any advice is appreciated!
Sophi

[Humberto]

[Sophi]

Humberto-
thanks ! for the code- I copied it exactly and started HTerm.
Nothing happens. Is there a setting I need to receive data from the PIC?
BTW LED works so code is working.
Thanks-
Sophi

[Jose]

#include<16f877a.h> //Change it to your Chip ##
#device ICD=TRUE
#fuses HS,NOLVP,NOWDT,PUT
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7) // Jumpers: 8 to 11, 7 to 12


void main(){
setup_adc( ADC_CLOCK_INTERNAL );
setup_adc_ports(ALL_ANALOG);
set_adc_channel(1);

while (TRUE){


printf("Look Behind You");

}
}
above is a small code to test the Hyper terminal make sure u have a serial port connected to your RS232
set your Hyper terminal to the following
9600
8
none
1
none

and it should keep writing that line forever

[rwyoung]

[sseidman]

And of course, take the extremely obvious step of making sure that hyperterminal is set correctly-- whichever Com port you're plugged into, 8 data bits, 1 stop bit, no parity, no flow control, and 9600 baud.

Scott

[Humberto]

After you checked all the steps suggested by rwyoung I would like
you check the following wiring:

[Sophi]

ummm....step 4, thanks Rob! I found a NULL cable at Staples this morning and will try this first. The board came pre wired but thanks for the info Humberto because I should check this too altho TX wiggles as it should.

Sophi

[Sophi]

Hi-
I still haven't gotten communications working-
-using NULL modem cable
-reread HTerm. links

while code is running...
MAX232 PIN 2.....+9V
PIN 6......-9V

PIC C6...............HIGH +5V
PIC C7...............???? +3.5V

All is wired as it should be (Thanks Humberto!)

When I look at the serial post (female) end on my Olimex protoboard with the scope, I see no signal at TX (pin 3), but see a signal at the MAX232 pin 12 and also at PIC C6. In case I have the wrong pin number for the serial end I have also looked at every pin and see no signal at the serial end. So how does the signal get into the computer?
Or do I not understand how the MAX chip works? (Yes I read the data sheet).
Thanks-
Sophi

[PCM programmer]

[Ttelmah]

In answer to the question "what does the Max232 'do'", there are two parts to the answer. Half the chip is a relatively standard inverting driver. It takes an incoming logic signal, inverts it, and drives the output with the result. It also works the other way, taking an incoming voltage signal, and inverting this. However the key thing is that RS232, defines the transmission voltages to be used, as both +ve, and -ve voltages, and somewhat above the 5v normally available on a logic board. The other half of the MAX232, is a set of charge pumps, which work together to generate about +9v, and -9v, from the incoming 5v. It is these voltages that are then used to drive the output of the inverter. The 'spec', says that the unit should give a minimum of +/-5v, and typically +/-8v on the outputs. Now the fact that these voltages are present, says that the output is not shorted out, and the charge pumps are running.

Best Wishes

[Humberto]

[Sophi]

still nothing-
I have changed out the MAX chip and also switched to another board in case either of these are bad.
I am using Olimex PIC P-40 protobaord with a 20mHz crystal.
The only wires I have put on this board are from TX->C6 and RX->C7.

Code is exactly Humberto's above minus ICD header.

I get no signal from the serial end on the Olimex bord, only highs and lows. I get a signal at C6 and on the MAX chip pin 12...shouldn't I see the same thing at the serial end? I am using a pull-up resister to poke in the holes of the serial end to look with the oscilliscope. Have tried this at both +5 and gnd.

Thanks-
Sophi