manzmike / nmea-gps-sentence-parsing

Pasring for the NMEA GPS Parsing type into C++

NMEA GPS Sentence Parser

Introduction

In this project, you will develop a program to parse (interpret) information output by a standard GPS receiver. These messages, or sentences, conform to a specification by the National Marine Electronics Association (NMEA). The primary goal is to build a parsing state machine that can take the NMEA GPS sentences one byte at a time and correctly interpret them.

Specifications

Input:

• NMEA GPS sentences in ASCII form.
• Each sentence starts with $, followed by a 5-character sequence starting with GP. Only four message types are valid: GPGGA, GPGSA, GPGSV, and GPRMC.
• Each sentence has a variable amount of message data.
• Sentences end with a * character followed by two checksum characters in hexadecimal format.
• Messages where the calculated checksum doesn't match the received checksum should be ignored.

Output:

• For every valid NMEA GPS sentence, the program should print:
  • Message type (e.g., GPGGA, GPGSA, GPGSV, GPRMC)
  • Message data (excluding $, *, and the checksum)
  • Message checksum

Functionality:

• Your program should be built as a state machine that reads one byte at a time.
• Calculate the checksum from the message data and verify it.
• Light LEDs based on the message type:
  • Green LED for GPGGA or GPRMC
  • Yellow LED for GPGSA
  • Red LED for any other type.

Development:

• Implement the parser using a C++ class.
• Use the provided Python script to send messages to your parser.
• Use the provided preliminary program (serial_read_start.cpp) as a starting point.

How to Run

Given the instruction:

> ./prog1 /dev/pts/2