Acoptex.com

members

Basics: Project 053f

Project name: NEO-6M GY-GPS6MV2 GPS module, White 0.96" I2C OLED display 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, GPS clock with local time, White 0.96" I2C OLED display module, I2C/TWI Interface, Arduino GPS real time clock, 0.96" I2C, White OLED display module, 128x64, 128x32, GMS096A, Adafruit Monochrome OLED, SSD1306

Attachments: NEOGPS_OLED_sketch and library,  library1, library2

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. 0.96" I2C OLED display module 1 pc

We will learn how to connect NEO-6M GY-GPS6MV2 GPS module, white 0.96" I2C OLED display module and use them to display GPS clock (local 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 adds time offset and converts UTC time to local time;
4. Arduino board prints local time, date, GPS position on the white 0.96" I2C OLED display module.

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 0.96" I2C OLED display module

You can read more about it here.

Understanding the NEO-6M GY-GPS6MV2 GPS module

You can read more about it here.

Signals and connections of the 0.96" I2C OLED display module

The nice thing about the 128x64 OLEDs is that they can be used with I2C (+ a reset line) or SPI. SPI is generally faster than I2C but uses more pins. It's also easier for some microcontrollers to use SPI. 

Make sure that you connect the power pins correctly. Some modules have GND and VCC swapped around. Don't blow up your display!

Data - Connected to I2C SDA if Adafruit OLED display module

Clk - SCK (Serial Clock) - SPI communication.The clock pulses which synchronize data transmission generated by the master. Connect to I2C SCL if Adafruit OLED display module.

SA0 (DC or D/C) - This is Data/Command control pin. When it is pulled HIGH , the data at D[7:0] is treated as data. When it is pulled LOW, the data at D[7:0] will be transferred to the command register. In I2C mode, this pin acts as SA0 for slave address selection.

RST (RES) - This pin is reset signal input. When the pin is pulled LOW, initialization of the chip is executed. Keep this pin HIGH during normal operation.

CS - (Chip Select) - the pin that the master can use to enable and disable specific devices.

3.3vo (3.3v) - this is the power pin. Should be connected to +3.3 VDC pin of Arduino board.

Vin - this is the power pin. 3 to 5V power supply. All OLEDs are safe to use with 3.3V logic and power.

VCC - this is the power pin. Can be connected to +5VDC or +3.3VDC pin of Arduino board (depends on the display module). All OLEDs are safe to use with 3.3V logic and power.

GND - ground. Connected to Arduino board GND pin.

SDA - Serial Data Line. Connected to Arduino Uno SDA or Analog pin A4. 

SCL - Serial Clock Line. Connected to Arduino Uno SCL or Analog pin A5.

D0 - Master In Slave Out (MISO) - SPI communication. The Slave line for sending data to the master. 

DI (DIN) - Master Out/Slave In (MOSI). SPI communication. The Master line for sending data to the peripherals. 

NC - Not in use. 

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 baud after you upload the sketch, Arduino will scan the address range looking for a reply.  The scanner can detect it (0x78, 0x7A,0x3C,0x3D) (for example, in our case 0x3C)
5. 
6. 
7. Modify the bold part in the line display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
8. Verify and upload the NEOGPS_OLED_sketch to your Adruino Uno.
9. You will see the GPS clock (date and time) and GPS position on LCD display. It will take some time before you will get the proper data. Time will be updated first, then date and then GPS position (when blue led on GPS module starts to flash). 
10. 
    

Summary

We learnt how to connect NEO-6M GY-GPS6MV2 GPS module, white 0.96" I2C OLED display module and use them to display GPS clock (local 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.
• Adafruit_SSD1306 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. You can read about it here.The SSD1306 driver library is used to initialize the display and provide low level display functions.
• Adafruit_GFX 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. You can read about it here.The GFX library provides graphics functions for displaying text, drawing lines and circles, etc. 
• Wire library included in Arduino IDE.

Sketch

• See attachments on the begining of this project