CobraV2

Table of contents

• CobraV2
  • Table of contents
  • Installation and compilation
    • Serial monitor tool
    • Monitoring tool
    • Sender and Reciever
  • Overview
    • Schema
      • Sender
      • Reciever
      • Master
    • Arduino Sender Format
  • Modules
    • 10 DOF IMU
    • L76K GPS
      • NMEA Sentence
    • NRF24L01+
  • Wiring
    • 10 DOF IMU Sensor
    • L76K GPS Module
    • NRF24L01+ Module
  • Issues / features
    • Sender issues
    • Monitor app issues
  • Sources

Installation and compilation

Serial monitor tool

git clone https://www.github.com/foglar/cobraV2.git
cd cobraV2/serial_read
go build .

Tip

You may have to delete go.mod file (if you have other go version) and go mod init the project. To install all dependencies you can use go mod tidy command or you can mannualy install them by go get [package] command.

Monitoring tool

git clone https://www.github.com/foglar/cobraV2.git
cd cobraV2/monitor
go build .

Important

For cross-compiling you will need to specify a CC to compile c-based libraries for pixel2 library. Example command: CC=x86_64-w64-mingw32-gcc GOOS=windows GOARCH=amd64 CGO_ENABLED=1 go build . For more information see: Pixel2 Wiki | Cross Compiling

Sender and Reciever

Upload sender and reciever code on the 2 arduino's

Required library for antenna: RF24

Overview

reciever_module/ - folder with code for reciver which will send data to the pc (arduino) sender_module/ - folder with code for sender, which transmit data to the reciever and save it on the micro sd card (arduino) serial_read/ - read serial input and save it monitor - folder with code for monitor which will recieve data and print them into the gui application (pc)

Schema

Sender

• device (arduino uno, arduino nano or arduino micro...) which recieves data from 10DOF IMU and L76K GPS, then it sends them via nrf24l01+ in sender format to reciever

Reciever

• device (arduino uno r4 wifi, arduino uno or arduino nano...) which recieves data from sender via nrf24l01+ and then send them through serial line to the master device in the sender format

Master

• device (pc, notebook, laptop), where the data are processed, parsed, saved and displayed realtime in the application monitor

Arduino Sender Format

• sender sends data via antenna to reciever in this format $[code of message];[value]*
• in future will be added some other values, like gps and so on

Identifier	Message Code	Value	Verificator
$	1;	temperature [degrees of Celsius]	*
$	2;	pressure	*
$	3;	altitude	*
$	4;	roll	*
$	5;	pitch	*
$	6;	yaw	*
$	7;	gyroscope x	*
$	8;	gyroscope y	*
$	9;	gyroscope z	*
$	10;	accelerometer x	*
$	11;	accelerometer y	*
$	12;	accelerometer z	*
$	13;	magnitude x	*
$	14;	magnitude y	*
$	15;	magnitude z	*

Modules

10 DOF IMU

• SDA (Serial Data)
• SCL (Serial Clock)
• INT (Interrupt) is a digital interrupt output
• FSYNC is a frame sync signal

L76K GPS

• PPS (Pulse per second) powers a led wich will blink and indicate that GPS is working
• RX (UART communication)
• TX (UART communication)

NMEA Sentence

$GPGAA,HHMMSS.SS,llll.ll,a,yyyyy.yy,a,x,xx,x.x,x.x,M,x.x,M,x.x,xxxx

Sentence Identifier	Time	Latitude	Longtitude	Fix Quality	Number of Satellites	Horizontal Dilution of Precision	Altitude	Height of geoid above WGS84 ellipsoid	Time since last DGPS update	DGPS reference station id	Checksum
$GPGAA	HHMMSS.SS	llll.ll a	yyyyy.yy a	x	xx	x.x	x.x M	x.x M	x.x	xxxx	*hh
$GPGAA	170834	4124.8963, N	08151.6838, W	1	05	1.5	280.2, M	-34.0, M	blank	blank	*75

Tip

Fix Quality: 0 = Invalid; 1 = GPS fix; 2 = DGPS fix; more about nmea sentences

NRF24L01+

• CE (Chip Enable) is an active-high pin. When enabled, the nRF24L01 will either transmit or receive, depending on the mode.
• CSN (Chip Select Not) is an active-low pin that is typically held HIGH. When this pin goes low, the nRF24L01 begins listening for data on its SPI port and processes it accordingly.
• SCK (Serial Clock) accepts clock pulses from the SPI bus master.
• MOSI (Master Out Slave In) is the SPI input for the nRF24L01.
• MISO (Master In Slave Out) is the SPI output of the nRF24L01.
• IRQ is an interrupt pin that can notify the master when there is new data to process.

Wiring

10 DOF IMU Sensor

Module	Arduino	Description
VCC	5V	Power input
GND	GND	Power ground
SDA	SDA	I2C data input
SCL	SCL	I2C clock pin

L76K GPS Module

Module	Arduino	Description
VCC	3.3V	Power input
GND	GND	Power ground
TX	RX	Serial communication
RX	TX	Serial communication
PPS	NC	Pulse per second

NRF24L01+ Module

Module	Arduino	Description
VCC	3.3V	Power input
GND	GND	Power ground
CE	9~	Chip enable
CSN	8	Chip select not
SCK	13	Serial Clock
MOSI	11~	SPI master out
MISO	12	SPI master in

Issues / features

Sender issues

• data stops being transmitted from sender after some short period time

Monitor app issues

• application crash after some period of time
• gui is not updating until it recieves serial input
• parser should be improved
• sender code should be improved
• gui window
• error messages as windows not terminal
• improve readability of code
• serial monitor setup port and baudrate

Sources

Datasheets, documentation and sources

• Waveshare 10 DOF IMU Sensor (D) - Arduino guide
• Waveshare 10 DOF IMU Sensor (C) - Demo code
• Waveshare 10 DOF IMU Sensor (C) - Documentation
• Waveshare L76K GPS Module - Arduino guide
• Waveshare L76K GPS Module - Demo code
• NRF24L01+ PA/LNA - Arduino guide
• NRF24L01+ Guide - Guide
• NRF24L01+ PA/LNA - Datasheet
• NRF24L01+ PA/LNA - Demo code
• Pixel2 (go gui library) - Github repository