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Topic: Max232 problem (Read 765 times) previous topic - next topic

binooetomo

Dear All

I build RS232 level shifter using max232, and use it wih NewSoftSerial at pin 4,5
My arduino is Arduino 2009

And here is my test script
Code: [Select]

#include <NewSoftSerial.h>  //Include library newsoftserial
#include <string.h>
char incoming_char=0;      //incoming char
char incoming_char_buff[300] ; //Incoming char buffer
int  incoming_char_idx = -1 ;  // Incoming char index
NewSoftSerial cell(4,5);
bool isprintline = 1;

void setup(){
  Serial.begin(19200);
  cell.begin(4800);
  delay(2000);
  Serial.println("Get Ready");
  delay(2000);
}
long myint = 0 ;
void loop(){
  /*
  cell.print("This is line number : ");
  cell.println(myint);
  Serial.print("This is line number : ");
  Serial.println(myint);
  myint++;
  delay(1000);
  */
  myint++;
  Serial.print("Loop Number : ");
  cell.print("Loop Number : ");
  Serial.println(myint);
  cell.println(myint);
 
  Serial.println("Let's check all lines");
  Serial.println("Check Cell Line");
  if(cell.available() >0){
    do_cell();
  }
  Serial.println("Check Serial Line");
  if(Serial.available() >0){
    do_ser();
  }
  delay(1000);
  if (isprintline){
    Serial.print("-----NO Thing Happen----------");
    cell.print("-----NO Thing Happen----------");
  }
  isprintline = 1 ;
}

void do_cell(){
  Serial.println("Reading Cell line");
  delay(100);
  incoming_char_idx=-1;
  while (cell.available()){
    incoming_char_idx++ ;
    incoming_char=cell.read();
    incoming_char_buff[incoming_char_idx]=incoming_char ;
  }
  if ( incoming_char_idx > -1){
    incoming_char_idx++;
    incoming_char_buff[incoming_char_idx]='\0';
    Serial.print("Cell Said : ");
    Serial.println(incoming_char_buff);
  }
  cell.flush();
  isprintline = 0 ;
}
void do_ser(){
  Serial.println("Reading Serial line");
  delay(100);
  incoming_char_idx= -1;
  while (Serial.available()){
    incoming_char_idx++ ;
    incoming_char=Serial.read();
    incoming_char_buff[incoming_char_idx]=incoming_char ;
  }
  if ( incoming_char_idx > -1){
    incoming_char_idx++;
    incoming_char_buff[incoming_char_idx]='\0';
    Serial.print("You type : ");
    Serial.println(incoming_char_buff);
    cell.println(incoming_char_buff);
    delay(1000);
  }
  isprintline = 0 ;
}



1. First, I test it to connect to my other PC via it's Com Port, and the result is :
a. When at the PC side I do not do monitor (i.e cat /dev/ttyS0) , the script output (at serial monitor window) just fine.
I can send text from PC to arduino and vise versa.
Arduino only detect any input on NewSoftSerial pin only if PC send text

b. When I do monitoring at PC side using --> cat /dev/ttyS0 ... the script output (at serial monitor window) start showing a "garbage"
Arduino always see there is "something" on NewSoftSerial pin ...

2. Second ... I change NewSoftSerial speed to 4800 , and attached my GPS (using cross cable), and the result is : Arduino start getting "garbage".

Attached is screen capture of my serial_monitor when GPS attached.

Kindly please give me your enlightment on how to fix it.

Sincerely
-bino-


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