Must be a problem in the SoftwareSerial read routine because I got the exact same results (unreadable nmea-like strings) with the following code - here I'm only using the software serial for the read part and the hardware uart for the write results to debug console. You'll notice in the main loop() the same results come from either the readbyte/printbyte method or readline/printline method (commented out). I also changed the name of the char2string function to getLine:
#include <ctype.h>
#define bit9600Delay 84
#define halfBit9600Delay 42
#define bit4800Delay 188
#define halfBit4800Delay 94
byte rx = 6; // EM406A GPS tx line connected to pin 6 on Arduino (4800baud)
byte SWval;
char line[80]="";
void setup() {
pinMode(rx,INPUT);
digitalWrite(13,HIGH); // turn on debugging LED
Serial.begin(4800); // Setup USB serial port monitor to 4800baud
}
int SWread()
{
byte val = 0;
while (digitalRead(rx));
//wait for start bit
if (digitalRead(rx) == LOW) {
delayMicroseconds(halfBit4800Delay);
for (int offset = 0; offset < 8; offset++) {
delayMicroseconds(bit4800Delay);
val |= digitalRead(rx) << offset;
}
//wait for stop bit + extra
delayMicroseconds(bit4800Delay);
delayMicroseconds(bit4800Delay);
return val;
}
}
void getLine()
{
int i = 0;
line[0] = SWread();
if (line[0] == 36) //string starts with $
{
i++;
line[i] = SWread();
while(line[i] != 13 & i<80) //carriage return or max size
{
i++;
line[i] = SWread();
}
line[i+1] = 0; //make end to string
}
} // end getLine()
void loop()
{
SWval = SWread();
Serial.print(SWval);
// getLine();
// Serial.println(line);
}
Am currently using the code at the following URL with perfect results using the EM-406 instead of the Parallax module (also connected via 3 wires pwr/gnd/tx):