EX_ADMM

[gmelcer]

Hi, I am looking for something to use to graph the values of a changing voltage. I plan to use a modified version of EX_ADMM.C to do this. However, I am still a beginner in using microcontrollers. I have hooked up (+5v) to VDD, (+5v) to MCLR, wires connecting pins 8 and 11, wires connecting 7 and 12, a 20mhz crystal oscillator to OSC1 and OSC2 with 22pf ceramic capacitors which are grounded, and GND to VSS. I am using pins 5, 3, and 2 of a 9 pin RS-232 port on a laptop computer in an attempt to communicate with the picmicro. Those pins are connected to TX, RX, and GND of the Picmicro. To generate an analog signal I am just using a small dc motor which I turn by my hand. The DC motor is connected to pin2 (A0) of picmicro. The settings I used with HyperTerminal with no success were baud= 9600, Data bits = 0, parity = None, Stop bits =1, and flow control = none. Why is this not working? Any suggestions?

[PCM programmer]

[gmelcer]

thanks, i will give that a try.

[gmelcer]

Hi, I tried adding a 22k resistor in series with the TX line but I am stilling not seeing any results on the computer. When i looked at the line with a oscilliscope I do see some sort of signal so i do believe it is trying to output some sort of data. I am not sure if this is useful for you but I included a copy of the code that I am using. If anyone could help me I would highly appreciate it.

#include <18F452.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7) // Jumpers: 8 to 11, 7 to 12



void main() {

int i, value, min, max;

printf("Sampling:");

setup_port_a( ALL_ANALOG );
setup_adc( ADC_CLOCK_INTERNAL );
set_adc_channel( 0 );

do {
min=255;
max=0;
for(i=0; i<=30; ++i) {
delay_ms(100);
value = Read_ADC();
if(value<min)
min=value;
if(value>max)
max=value;
}
printf("\n\rMin: %2X Max: %2X\n\r",min,max);

} while (TRUE);
}

thanks george

[PCM programmer]

From my previous post:

[Guest]

I included the "INVERT" directive and reprogrammed the PIC. I still do not get anything on the computer? I unplugged the RX wire from the picmicro controller as well since it is not being used. After putting in the "INVERT" directive the TX Pin is at -5V. Is that good? any other ideas?

[PCM programmer]

[asmallri]

[treitmey]

For debug, I've never used a "real" level converter. 3 years, working every weekday, I've yet to blow a pic to my knowledge.
Just my 2cents. Don't want to fight, or suggest that this is what you should do. Just giving you my statistics.
btw. for me, PICs are very easy to replace.
I have many floating around here.

[jbmiller]

First thing I'd do is tie pins 2 and 3 of your serial cable together and verify that Hyperterminal is working OK. Typing on the PC keyboard should be echoed onto the screen.
I know a small, 'baby' step, but sometimes it's best to verify that the 'little' things that should work, really are !
been there-done that as the saying goes..

Isn't pin 2 of a de-9 RCv and not Xmt( as in a DB-25 ) ? That can be a 'gottcha' too.....

Jay

[Guest]

Hi, I have made sure all the pins and everything are hooked up correctly. I have tried just about everything so I decided to change the code around to just print a value to the rs232 line everything 1/10 of a second. I disabled all the ADC stuff. I am just trying to get the PIC to talk to the computer. When I looked at pin C6 though nothing is coming out of it no matter what I do. It shouldn't matter whether or not the serial line is connected properly for something to at least come out of the pin? When I search this stuff on google it seems like everyone is using the MAX232 chip? Should I be using that? Any suggestions? Thanks for your help. GEORGE

[asmallri]

[Guest]

my interface for the TX line is just a 22k resistor in series. The RX line is connected directly to the PIC. I don't believe I have ever observered "latchups" (I am just an ameture hobbiest right now so i am not that expirenced but I am currently a freshman majoring in electrical and computer engineering). I do not recall seeing any odd behavior on the PC's part or the PIC part. I think I need to update the version of Hyperlink on the laptop which I a using because it doesn't let you input data. thanks

[Guest]

could this be the problem?
http://www.airborn.com.au/rs232.html

[sonicdeejay]

Will it works....if i connect..that way...I am using 18f2331/2431

PIN 17(TX) --------> RX of RS232
PIN 18(RX) --------> TX of RS232


thanx

sonic