Trouble getting NMEA output from Reach RS+ to Arduino over RS232 serial communication

Hi, I’m having trouble receiving NMEA output from Reach RS+ over the Reach RS+/RS2 cable 2m with DB9 MALE connector via an DB9 RS232 Serial to Terminal Block Adapter to an Arduino Uno.

ReachView version: v2.18.1

The connection are as follows:

  • Reach_Rx (DB9 Pin 2) to pin 4 on Arduino
  • Reach_Tx (DB9 Pin 3) to pin 3 on Arduino
  • Reach_GND (DB9 Pin 5) to GND on Arduino

Voltage between Reach_Tx to GND: 4.21- 4.46 V
Voltage between Reach_Rx to GND: ~0.0 V

I have followed the schematics: Reach RS232 port and RS Connecter to DB9 Male.

I’m using the TinyGPS++ code example “DeviceExample” with serial monitor (57600 baud rate) and the Reach RS+ outputting Serial, UART, NMEA, baud rate: 57600.

Here is my code:

Summary

#include <TinyGPS++.h>
#include <SoftwareSerial.h>
/*
This sample sketch demonstrates the normal use of a TinyGPS++ (TinyGPSPlus) object.
It requires the use of SoftwareSerial, and assumes that you have a
4800-baud serial GPS device hooked up on pins 4(rx) and 3(tx).
*/
static const int RXPin = 4, TXPin = 3;
static const uint32_t GPSBaud = 57600;

// The TinyGPS++ object
TinyGPSPlus gps;

// The serial connection to the GPS device
SoftwareSerial ss(RXPin, TXPin);

void setup()
{
Serial.begin(57600);
ss.begin(GPSBaud);

Serial.println(F(“DeviceExample.ino”));
Serial.println(F(“A simple demonstration of TinyGPS++ with an attached GPS module”));
Serial.print(F("Testing TinyGPS++ library v. ")); Serial.println(TinyGPSPlus::libraryVersion());
Serial.println(F(“by Mikal Hart”));
Serial.println();
}

void loop()
{
// This sketch displays information every time a new sentence is correctly encoded.
while (ss.available() > 0)
if (gps.encode(ss.read()))
displayInfo();

if (millis() > 5000 && gps.charsProcessed() < 10)
{
Serial.println(F(“No GPS detected: check wiring.”));
delay(1000);
}
}

void displayInfo()
{
Serial.print(F(“Location: “));
if (gps.location.isValid())
{
Serial.print(gps.location.lat(), 6);
Serial.print(F(”,”));
Serial.print(gps.location.lng(), 6);
}
else
{
Serial.print(F(“INVALID”));
}

Serial.print(F(" Date/Time: “));
if (gps.date.isValid())
{
Serial.print(gps.date.month());
Serial.print(F(”/"));
Serial.print(gps.date.day());
Serial.print(F("/"));
Serial.print(gps.date.year());
}
else
{
Serial.print(F(“INVALID”));
}

Serial.print(F(" “));
if (gps.time.isValid())
{
if (gps.time.hour() < 10) Serial.print(F(“0”));
Serial.print(gps.time.hour());
Serial.print(F(”:"));
if (gps.time.minute() < 10) Serial.print(F(“0”));
Serial.print(gps.time.minute());
Serial.print(F(":"));
if (gps.time.second() < 10) Serial.print(F(“0”));
Serial.print(gps.time.second());
Serial.print(F("."));
if (gps.time.centisecond() < 10) Serial.print(F(“0”));
Serial.print(gps.time.centisecond());
}
else
{
Serial.print(F(“INVALID”));
}

Serial.println();
}

I receive location data from both my Reach RS+ Base and rover, but can’t receive the information from either of the Base and Rover over the RS232 port . I have tried switching the Rx and Tx pins. Do I need a RS232 to TTL converter board? What is their else left to try?

I hope you can help.

Best,
Kaspar

https://store.arduino.cc/usa/arduino-uno-rev3

Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data. These pins are connected to the corresponding pins of the ATmega8U2 USB-to-TTL Serial chip.

So the Arduino is TTL level and the RS+ is RS232 level.

A converter is required.

Now. Seeing that you have already connected it, there may have been damage to the Arduino. The absolute maximum rating for the input pins is Vcc + 0.5V which means a max of 6 Volts. RS232 is +/- about 25 Volts so be prepared for further problems. But you never know, you might get lucky. :crossed_fingers:

Screenshot of the ATmega8U2 Electrical Characteristics:

2 Likes

Thanks for the quick answer!

I will buy the converter.

It didn’t seem to damage my Uno, but hope it will work.

Best,
Kaspar

1 Like

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