SoftwareSerial interface not receiving data

Projects Programming
1

I have a Sparkfun RS232 Shifter SMD part at the moment, and attached to that is a loopback serial connection (basically echoes back whatever is transmitted to it, I have tested this on another system and it is working). I am using this code:

#include <SoftwareSerial.h>

SoftwareSerial zytronics(2,3);

void setup()
{
    Serial.begin(115200);
    Serial.println("Start zytronics test");
    zytronics.begin(9600);
}

void loop()
{
  zytronics.print("Z");
  while(zytronics.available())
  {
    Serial.print(zytronics.read());
  }
  delay(500);
}

And I never receive anything to read, despite it coming through (the RS232 shfiter is blinking both TX and RX lights indicating that both events are happening, as expected with a loopback).

What can I do to make this right?

EDIT: It's also worth noting that when I put my RX pin into the Digital pin 0 (the Arduinos RX) I can receive this data.

2

How about:

void loop(void)
{  zytronics.print("Z");
   while (!zytronics.available()) ;
   Serial.print(zytronics.read());
   delay(5);
}

Edit: added missing parenthesis

3

Still no go unfortunately, and I've tried it on a variety of different pins that I know work

4

The only other thing that I can think to try might be separating the Serial and zytronics calls:
(If you're not doing cut-n-paste, don't omit the '!')

char x;

void loop(void)
{  zytronics.print("Z");
   while (!zytronics.available()); /* wait for data */
   x = zytronics.read();
   Serial.print(x);
}
5

The SoftwareSerial library is half duplex, it cannot send and receive at the same time. So you'll never be able to use it to do a loopback test.

6

Thanks! That's good to know.

7

That makes sense, thanks