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Basics: Project 053e

Project name: NEO-6M GY-GPS6MV2 GPS module, LCD 2004 I2C module - GPS-based timing

Tags: Arduino, Arduino Uno, NEO-6M GPS module, GY-NEO6MV2 GPS Module, GY-GPS6MV2, NEO6MV2, TinyGPSPlus library, TinyGPS++ library, NeoGPS library, UBOX, GPS clock with Neo 6M, GPS-based timing, time, position, date, LCD 2004 I2C module, LCD 2004 module, GPS clock with local time, LCD2004, I2C/TWI Interface, Arduino GPS real time clock, UTC time

Attachments: NEOGPS_SD_LCD2004I2C_2sketch and library, libraryNewLiquidCrystal

In this project, you needed these parts (Dear visitors. You can support our project buy clicking on the links of parts and buying them or donate us to keep this website alive. Thank you):

1.Arduino Uno R3 (you can also use the other version of Arduino)

2. NEO-6M GY-GPS6MV2 GPS module (it comes with an external antenna, and does’t come with header pins. So, you’ll need to get and solder some) 1pc

3.Arduino IDE ( you can download it from here  )

4.Jumper cables F-M, M-M

5.Resistor 2 pcs (10 KOhm 1pc and 4.7KOhm 1 pc)

6.Breadboard half size or small size 1 pc

7. LCD 2004 I2C module (or LCD2004 + I2C Driver module)1 pc

General

We will learn how to connect NEO-6M GY-GPS6MV2 GPS module, LCD 3004 I2C module and use them to display GPS clock (UTC time and date) and GPS position.

Project sequence:

1. The GPS module receives data from satellites;
2. Arduino board receives time, date, position (UTC time) from the GPS module;
3. Arduino board prints them on the 20×4 LCD.

GPS-Based Timing

GPS receivers can be used to provide highly accurate time information. For this reason the u-blox 6 Timing GPS module includes a specific Time Mode, which assumes a known antenna position and calculates a time pulse synchronized to either GPS or UTC (Coordinated Universal Time).

The base of all timing and frequency applications is the one pulse per second (1PPS) time pulse, which is synchronized to GPS time or UTC.

Single satellite navigation can be useful under poor GPS reception conditions. Time information can be heavily degraded due to multipath effects. To avoid such degradation choose an antenna that primarily receives satellites with high elevation angles. 

When adjusting the time pulse the user should take the electrical delay into account, due to the cable length connecting the antenna with the GPS receiver. In addition an arbitrary user delay can be considered to calibrate the time pulse to a given reference time.

Accuracy of time pulse

Configuration of the time pulse depends on the application. A low time pulse frequency e.g. 1 Hz is best for exact timing measurements. The accuracy of the time pulse can be measured in terms of a difference to a reference time. The reference time should be as accurate as possible and is normally generated by a GPS receiver, which is synchronized to a rubidium clock.

The timing error consists of three parts:

1. A constant error caused by delay from the antenna cable and from the receiver.
2. A short-time error from pulse to pulse related to generation and quantization of the time pulse.
3. The position uncertainty caused by multipath effects or caused by different transit times to the ionosphere.

The first error term can be removed by assuming a certain cable delay in the configuration table. The second error term relating to the quantization error can be compensated by using the UBX-TIM-TP message. The last error term related to the multipath effect can be minimized by using an antenna with suitable antenna pattern in conjunction with single satellite navigation.

Frequency accuracy

A faster time pulse e.g. 8 kHz or more is used for accurate frequency measurements.

Frequency stability

Frequency stability depends on the observation time and is measured in terms of Allan deviation or phase noise. u-blox time pulse shows excellent long-term stability and reasonable short-term stability, but it is not designed for improved phase noise performance for reasons that will be discussed in the next sections.

Allan deviation

Allan deviation is typically measured for observation or integration intervals from 1 s to some 1000 s or even more. It is a time domain fractional frequency measure which was initially used to characterize oscillators suffering from aging and ambient effects. In this instance the Allan deviation, which is the square root of the Allan variance, provides better results than the standard deviation calculated from a set of data. A typical curve is shown in Figure 5. An observation interval around 1 s refers to short-term stability and above some seconds refers to long-term-stability. Because of the fractional frequency usage Allan deviation is dimensionless and plotted versus the observation interval.

Phase noise

Short-term stability with uncertainties lower than 0.1 s is measured in terms of phase noise. In practice, the noise power in a single sideband over a bandwidth of 1 Hz with respect to the frequency offset from the carrier is measured to characterize phase noise. If related to the total signal power, phase noise is given in dBc/Hz. Since the time pulse is derived from a 48 MHz clock it suffers from an additional jitter due to quantization or granularity of the clock. Be aware, that the time pulse is not designed for improved phase noise specification.  If necessary the customer must add an external circuit e.g. a phase lock loop. Picture below shows an example of how to improve phase noise performance. A phase lock loop is added to the time pulse output to synchronize the time pulse to an external oscillator. If additional holdover performance is required an oven-controlled oscillator should be used instead of a temperature-controlled oscillator.

Understanding the NEO-6M GY-GPS6MV2 GPS module

You can read more about it here.

Understanding the LCD 2004 I2C module

You can read more about it here.

Signals and connections of LCD 2004 I2C module

As you can see on the back of LCD 2004 I2C module there are 4 connections: GND (-), VCC (+5V), Serial Data Line (SDA),(Arduino SDA pin)  and Serial Clock Line (SCL) (Arduino SCL pin).

Signals and connections of the NEO-6M GY-GPS6MV2 GPS module

The NEO6MV2 GPS module comes with 4 connections: RX, TX, VCC and GND, which is quite easy to incorporate with using SoftwareSerial on an Arduino Uno or a serial interface on an Arduino Mega. The power supply of the NEO6M should be 3.6V at max according to the datasheet. The typical China-produced breakout-boards contain a voltage regulator so that 3-5V VCC so it does not harm the board. Since the digital pins also produce 5V, the voltage divider is used on the receivers RX channel since this is not regulated.

RX (or RXD) - receive pin. Connected to Arduino board TX pin.

TX (or TXD) - transmit pin. Connected to Arduino board RX pin.

VCC - power supply. Can be connected to +5VDC or +3.3VDC pin of Arduino board.

GND - ground. Connected to Arduino board GND pin.

PPS - Pulse per second. This is an output pin on some GPS modules. Generally, when this pin toggles, once a second, you can synchronize your system clock to the GPS clock.

Wiring

Step by Step instruction

1. Do wiring.
2. Open Arduino IDE.
3. Plug your Adruino Uno board into your PC and select the correct board and com port
4. Find your I2C address. Each device has an I2C address that it uses to  accept commands or send messages. Load the sketch over at http://playground.arduino.cc/Main/I2cScanner and follow the instructions to use it.  By opening up the Serial monitor at 9600 bound after you upload the sketch, Arduino will scan the address range looking for a reply.  Even though the documentation said it was 0x27, this scanner can detect different (in my case 0x3F)
5. Modify the sketch in attachments above (you can use the sketch below too): the line LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6,7, 3, POSITIVE) (See part marked bold)
6. Verify and upload the NEOGPS_SD_LCD2004I2C_2sketch to your Adruino Uno.
7. You will see the GPS clock and GPS position on LCD display.
8. 

Summary

We learnt how to connect NEO-6M GY-GPS6MV2 GPS module, LCD 3004 I2C module and use them to display GPS clock (UTC time and date) and GPS position. 

Notes:

• It takes for about half a minute or one to read the data by the GPS module initially when you run it, so do not panic for this it’s very usual.
• It happens in some case that it is unable to detect the data that might be the issue with antenna, so unplug the antenna( if it is detachable) and attach it again.
• If, code says “Check Connection”, then you should definitely check it twice, before giving up. Also, sometimes interchanging the TX and RX pins is preferable and surprisingly works.

Code

The TinyGPS++ library allows you to get way more information than just the location, and in a simple way. Besides the location, you can get: date, time, speed, course, altitude, satellites, hdop and so on. You can read more  about the TinyGPS++ library here.

Library

• All libraries attached on the begining of the project description
• TinyGPS++ library. Download, unzip  and add to libraries in our PC, for example C:\Users\toshiba\Documents\Arduino\libraries. This link you can find in Preferences of Adruino IDE program which installed in your PC. 
• SoftwareSerial library included in Arduino IDE.  
• The library has the following known limitations:
  If using multiple software serial ports, only one can receive data at a time.
  Not all pins on the Mega and Mega 2560 support change interrupts, so only the following can be used for RX: 10, 11, 12, 13, 14, 15, 50, 51, 52, 53, A8 (62), A9 (63), A10 (64), A11 (65), A12 (66), A13 (67), A14 (68), A15 (69).
  Not all pins on the Leonardo and Micro support change interrupts, so only the following can be used for RX: 8, 9, 10, 11, 14 (MISO), 15 (SCK), 16 (MOSI).
  On Arduino or Genuino 101 the current maximum RX speed is 57600bps
  On Arduino or Genuino 101 RX doesn't work on Pin 13
  The library has the following known limitations: If using multiple software serial ports, only one can receive data at a time;Not all pins on the Mega and Mega 2560 support change interrupts, so only the following can be used for RX: 10, 11, 12, 13, 14, 15, 50, 51, 52, 53, A8 (62), A9 (63), A10 (64), A11 (65), A12 (66), A13 (67), A14 (68), A15 (69);Not all pins on the Leonardo and Micro support change interrupts, so only the following can be used for RX: 8, 9, 10, 11, 14 (MISO), 15 (SCK), 16 (MOSI);On Arduino or Genuino 101 the current maximum RX speed is 57600bps; On Arduino or Genuino 101 RX doesn't work on Pin 13
• We have used the library - NewliquidCrystal_1.3.4.zip which we downloaded, unzipped, changed the name of folder to LiquidCristal and added to libraries in our PC, for example C:\Users\toshiba\Documents\Arduino\libraries. This link you can find in Preferences of Adruino IDE program which installed in your PC.
• If you have LiquidCristal folder in this location already - delete this folder and copy folder, which was made by you, to this location.

Sketch

• See attachments on the begining of this project