FarmBox1. IntroductionDevice designed for high accuracy (15-30 cm from pass to pass) positioning agricultural equipment, which perform field work. FarmBox is a separate block, which is installed on the tractor’s roof. Device working in two modes:

tracker mode. Register and accumulate information about current position and transmit it to remote server.

GNSS receiver mode. Transmit current coordinates in NMEA format through Bluetooth or/and RS232.

Figure 1. FarmBox: system architecture.

2. System Architecture

GNSS Sensor [2] receive coordinates from GNSS Satellites [9] (GNSS sensor supports: GPS, GLONASS, GALILEO navigation systems and SBAS [WAAS, EGNOS]  augmentation system) and transmeet it, compliant NMEA 0183, to microcontroller (MCU [6]).

Accelerometer [1] – transmits data about acceleration of the vehicle to microcontroller.

Magnetic Compass [3] – transmits data about direction of magnet field (orientation relative to the magnetic poles of the Earth) of the vehicle to microcontroller.

CAN (ISOBUS) [8] – transmit to microcontroller Tractor [13] data onboard computer (speed, tachometer etc).

MCU [6] (microcontroller) – processes the data from GNSS Sensor, Accelerometer, Magnetic compass, CAN, accumulates high accuracy coordinates in internal flash and transmits it, compliant NMEA 0183, to Bluetooth transceiver, Cellular transceiver, RS232 transceiver. Receive configuration commands by USB or Cellular Transceiver.

Bluetooth transceiver [4] – transmit high accuracy coordinates, compliant NMEA 0183, to Android Device [10].

RS232 transceiver [5] – transmit high accuracy coordinates, compliant NMEA 0183, to External Navigator [10].

External Navigator [12] – displays current vehicle position on map, it’s can be tractor onboard computer or navigator, compliant NMEA 0183.

Cellular Transceiver [7] – transmit coordinates, compliant NMEA 0183, to Remote Server [11] and receive configuration commands by SMS, GPRS.

2.1 Device has two modes:

a. GNSS receiver mode. Device transmit by Bluetooth or/and by RS232: precise time in Greenwich; coordinates: latitude, longitude, altitude WGS-84, corrected with

account all amendments (SBAS, moving direction using internal compass, acceleration using internal accelerator);

oexclude unnecessary points on a straight section of the route;

odetailed description of turns (add extra points); speed; orientation relative to the magnetic poles of the Earth.

b. Tracker mode. Device accumulates and transmit to Remote Server: data from GNSS receiver; transmit data in real time when there is a connection; accumulates coordinates in internal flash when there is no

connection; diagnoses the status of the device through USB/GPRS; supports configuration by SMS, GPRS; transmit data from CAN BUS.

Device support remote firmware recording.

Figure 2. FarmBox: functional diagram.

3. Functional description. When there is external power supply, microcontroller asks accelerometer. If there is no acceleration, microcontroller going to sleep mode and wakes up each 60 seconds, asks accelerometer, else microcontroller asks GNSS module and accelerometer each 1 second, determinates current position write into flash and:

in GNSS receiver mode, continuously transmit by Bluetooth or/and by RS232 data mentioned above in paragraph 2.1.a;

Tracker mode. Server Device accumulates and continuously transmit to Remote server data mentioned above in paragraph 2.1.b.

When there is no external power supply, microcontroller asks accelerometer each 1/10/30/60 minutes (set externally through USB, SMS, GPRS). If there is no acceleration, microcontroller going to sleep mode, else microcontroller asks GNSS module, determinates current position, write it into flash and send current position each 10/30/60/120 minutes (set externally through USB, SMS, GPRS) by cellular module to remote server.GNSS module works in sleep mode, until microcontroller wake it up; it’s send to microcontroller current position.Cellular module configured by microcontroller, depending device working mode:

sleep mode; transfer mode – one time transfer (10/30/60/120 minutes); transceiver mode – continuous receive/transmit.

Bluetooth module configured by microcontroller, depending device working mode:

sleep mode; transceiver mode – continuous receive/transmit.

RS232 module is works in standby mode until external request, after it transmit current coordinates.

Connectors 15, 17 can be united into one, compliant IP67 (D-Sub 9P: 09675097658 Harting).

Power Connector [1] – high power connector, compliant IP67 (KLS15-249-2B).

UV/OV protect [2] – undervoltage/overvoltage protection. Input voltage monitored by MAX16127, which turns off STD20NF06L when input voltage higher 26V or lower 9V; maximum input voltage – 100V, working voltage 9…26V. DC/DC converter [3] – three step down direct current converters: TPS5450 – converts 9…26V to 5V 3A max (power supply for all systems), MIC29302 – converts 5V(9…26V) to 4.2V 4.5A max(supply for cellular module), TLV1117 – converts 5V to 3.3 V 800 mA max (supply for Main Chip and peripherals).Backup Battery [4] – lithium polymer battery 3.7V 300…4000 mA/h (optional). Without external power supply devise working in sleep mode, wake-up after external event or signal from accelerometer, write events and current coordinates into internal flash, send last sample each hour (30 min, 10 min, 1 min).Battery charger [5] – MAX1555EZK – low cost 5V charger. BQ24100RHLR – charger with high accuracy voltage, current regulation and battery temperature monitoring. Select one of them.Debug Interface [6] – pin pads for debugging and writing firmware into main chip internal flash.GNSS module [7] – Global Navigation Satellite System receiver, using GPS, GALILEO, GLONASS, SBAS (can use one of the listed below: RXM-GNSS-GM Linx Technologies; RXM-GNSS-TM Linx Technologies; Jupiter SL869 Telit Wireless Solutions; Jupiter SL871 Telit Wireless Solutions; NEO-M8N u-blox, M10478-A3 Antenova; GNSS L16 Quectel Wireless Solutions; LR9130 LEADTEK; A5100-A Maestro-Wireless) receive and transmit through UART to

Main Chip flowing date, time, coordinates corrected by the system SBAS corrections (or not corrected coordinates and corrections received by SBAS), speed.Cellular module [8] - Cellurar module using GPRS, HDSPA (can use one of the listed below: HE910 Telit Wireless Solutions [have embedded GNSS]; UL865 Telit Wireless Solutions; SARA-U270 u-blox; LISA-U200 u-blox; LISA-U230 u-blox; LISA-U270 u-blox; UC15 Quectel Wireless Solutions; UC20 Quectel Wireless Solutions) receive through UART from Main Chip and transmit to server: date and time in Greenwich; coordinates: latitude, longitude, altitude, corrected with account all amendments (SBAS, moving direction using internal compass, acceleration using internal accelerator). Receive from server configuration commands and updated firmware for Main Chip.

SIM Holder [10] – connector for SIM card .

Litium Battery 3V [9] – backup battery for clock.

Accelerometer and Magnetometer [11] – LSM303D accelerometer and compass in one chip; transmit through I2C or SPI to Main Chip acceleration and direction of magnet field (orientation relative to the magnetic poles of the Earth).

Bluetooth module [12] – module compliant Bluetooth 4.0 protocol (can use one of the listed below: OBP421 u-blox; OBS421 u-blox; CC2560 Texas Instruments;), receive from Main Chip and transmit to external Android device date and time in Greenwich; coordinates: latitude, longitude, altitude, corrected with account all amendments (SBAS, moving direction using internal compass, acceleration using internal accelerator).

Flash Memory 4GB/8GB/16GB [13] – internal flash memory MT29F04G08/MT29F08G08/MT29F16G08 (according to size 4-,8-,16- GB) for saving current device location data.

RS232 [14] – MAX3221 chip transfer current device location data to external devises by RS-232, compliant with NMEA 0183.

CAN[ISOBUS] [16] – connecting to tractor service bus compliant with SAEJ1939 standard. Use SN65HVD230 or MCP2551T.

USB – bus for diagnostic and configuration device.

Main Chip [18] – central microcontroller (can use one of the listed below: STM32F103 ST Microelectronix; STM32F439 ST Microelectronix) receive coordinates from GNNS and processes data from all sensors, adjust position and write data to internal flash and transmit it to Cellular module and Bluetooth module.

Box – body should have a magnetic and mechanical attachment to the tractor roof, compliant IP67; all antennas installed inside of box; top lid transparent for radio waves. For the first prototypes can use standard boxes G3xxMF Gainta. Should also be developed technological equipment for box.

Appendix 1…4 shows tables for main modules: Appendix 1 - Main Chip; Appendix 2 – Bluetooth module; Appendix 3 - Cellular module; Appendix 4 - GNSS module.

4. Software. Device is in sleep mode till the emergence of acceleration. Microcontroller wakes up and:

a. in tracker mode – receives data from GNSS module accumulates it and sends by cellular module to remote server.

b. GNSS receiver mode – receives data from accelerometer, compass, GNSS module measures deviation, corrects position, accumulates data and sends it by RS232 and/or Bluetooth.

Figure 3. FarmBox: Software Flowchart.

Sleep [1] – microcontroller works in sleep mode and wakes up each 60 seconds, asks accelerometer.

Acceleration [2] – if there is acceleration microcontroller starts working (Start [3]), else microcontroller goes to sleep mode.

Settings sent by USB or Cellular module [4] – modes are set (Tracker mode or GNSS receiver mode) by USB or Cellular module.

Device Mode [5] – device has two working modes: Tracker mode; GNSS receiver mode, settings are stored in external flash.

GNSS receiver mode [6] – mode set by user. In this mode device corrects coordinates and send it to android device or external navigator.

Tracker mode [7] – mode set by user. In this mode device is registering and accumulate information about current position and transmit it to remote server.

Power Flag [8] – if there is no external power supply, device goes to Battery Power Supply mode [10], else device works in External Power Supply mode [9]. In GNSS receiver mode device always works in External Power Supply mode.

Receiving data from GNSS, Accelerometer, Compass [11] – microcontroller request data from GNSS receiver (coordinates, augmentation data), Accelerometer, Compass.

GPS Data Filtering [12] – filtering wrong GPS points.

Measurement Deviation [13] – error calculation based on data obtained GNSS receiver, Accelerometer, Compass.

Adjustments of Coordinates [14] – amendment to the current location.

Data Buffering [15] – microcontroller writes data to external flash in tracker mode; microcontroller writes data to internal RAM in GNSS receiver mode.

Timer [16] – in battery power supply mode current position data, writes into flash and send current position each 10/30/60/120 minutes (set externally through USB, SMS, GPRS) by cellular module to remote server.

Transmit by RS232, Bluetooth [17] – data transfer to android device or external navigator in real time.

Transmit by Cellular Module [18] – accumulated data are transmitting to remote server.

5.Testing and certification of the deviceDevise is tested for compliance with standards electrical safety (IEC 60950), EMC (CISPR 22, CISPR 24, CISPR 11), by methods specified in these standards in third-party labs.Self-testing. Microcontroller sends test requests to internal modules.Manual testing. Testing of internal modules compliance to technical requirements.Main parameters to be tested:

Power supply and power protect: operation voltage 9-26V; maximum voltage 100V;

CAN (ISOBUS) should connect and receive data from onboard computer vehicle ;

RS232: should connect to external navigator and retrieve data; Bluetooth: device should connect to and transfer data continuously; Accuracy of the device. Move the device a known trajectory and

compare the data with reference or use reference receiver (RTK system) and compare the data. These tests should be conducted in geographic areas where device is operated.

Appendix 1 - Main Chip

Manufacturer

Country Web Model

Internal Flash

RAM FCPU UART USB CAN FSMC

TFT LCD Controller

Unit Price

$

ST Microelectronix

USA www.st.com/

STM32F103 1M 96KB 72MHz 5 1 + 16/8 k - 6

STM32F439 2M 256KB 180MHz 8 1 2 16/8 k + 9,2

Appendix 2 - Bluetooth moduleManufacturer Country Web Model Processor on

board Interfaces GPIO SPP Unit Price $ Notes

u-blox Switzerland

http://www.u-blox.com/en/

OBP421

2 MHz, ARM 32-bit Cortex

M3 processor with 64 kB RAM and

384 kB flash

SPIUART 21 + 56

module, Android

connectivity

OBS421 ND UART 9 + 42module, Android

connectivityTexas Instruments

USA http://www.ti.com CC2560 - UART + 2,12 Chip

Appendix 3 - Cellular module

Manufacturer Country Web Model

Embended GNSS

Cellular Technology Interfaces

Packarge

Operating Voltage, V

Unit Price $

Telit wireless Solutions

Italy

http://www.telit.com

HE910 GPS

HSPA+/UMTS/-850/900/AWS1700/1900/2100MHZ

GSM/GPRS/EDGE-850/900/1800/1900MHZ

USB/2UART/

SPIBGA 3,4-4,2

UL865 - HSPA/UMTS-900/2100MHz GSM/GPRS/EDGE-850/1800MHz

USB/UART/

SPISMD 3,4-4,2

u-blox Switzerland

http://www.u-blox.com/en/

SARA-U270 - GSM/GPRS - 900/1800 MHz,

HSPA/UMTS - 900/2100 MHzUART/

SPI/USB BGA 3,3-4,4

LISA-U200 -

GSM/GPRS - Quad Band, HSPA/UMTS -

800/850/900/1700/1900/2100 MHz

UART/SPI/USB SMD 3,3-4,4

LISA-U230 -

GSM/GPRS - Quad Band, HSPA/UMTS -

800/850/900/1700/1900/2100 MHz

UART/SPI/USB SMD 3,3-4,4

LISA-U270 - GSM/GPRS - 900/1800 MHz,

HSPA/UMTS - 900/2100 MHzUART/

SPI/USB SMD 3,3-4,4

Quectel Wireless Solutions

China

http://www.quectel.com

UC15 - 850/1900MHz@UMTS850/900/1800/1900MHz@GSM

UART/USB BGA 3,4-4,3 36,4

UC20

GPS/

GLONAS

S

800/850/900/1900/2100MHz@UMTS

850/900/1800/1900MHz@GSM

UART/USB BGA 3,4-4,3 36,44

Appendix 4 – GNSS module

Manufacturer Country Web Model System

SupportArchitect

ureOperating Voltage, V

Interfaces

Packarge

Accuracy, m

Chanels

Hot Start, s

Cold Start, s DGPS Standarts

Tracking

Sensitivity,

dBm

Unit Price $ Notes

Linx Technologies

USAhttps://www.linxtechnologies.com/en/home

RXM-GNSS-GM

GPS, GLONASS, GALILEO, QZSS

Mediatek MT3333 3-4,3 UART SMD 1,5 99 1 33 WAAS,

RTCM NMEA -161 25,47

RXM-GNSS-TM

GPS, GLONASS, GALILEO, QZSS

Mediatek MT3333 3-4,3 UART SMD 2,5 99 1 33 WAAS,

RTCM NMEA -164 23 For battery

Telit wireless Solutions

Italy http://www.telit.com

Jupiter SL869

GPS, GL ONASS, Galileo

Mediatek MT3333 3-3,6

UART, I2C, USB, CAN

LLC (SMD) 1,5 32 1 35

EGNOS, WAAS, MSAS

NMEA, RTCM 104 -162 24

Jupiter SL869 V2

GPS, GL ONASS, Galileo, Beidou

Mediatek MT3333 3-3,6 UART,

SPI, I2CLLC (SMD) 3 33 1 35

EGNOS, WAAS, MSAS

NMEA -165

Jupiter SL871

GPS, GLONASS, GALILEO, QZSS

Mediatek MT3333 3-3,6 UART,

SPI, I2CLLC (SMD) 3 1 35

EGNOS, WAAS, GAGAN, MSAS

NMEA -165

u-blox Switzerland

http://www.u-blox.com/en/ NEO-M8N

GPS, GLONASS,, QZSS, Galileo ready with future firmware

2,7-3,6

UART, USB, SPI or I2C

SMD 2 72 1 26WAAS, EGNOS, MSAS

NMEA, UBX -167 u-blox’

PPP

Antenova UK http://www.antenova-m2m.com

M10478-A3

GPS, GLONASS, GALILEO, QZSS MT3333 2,8-4,3 UART SMD 2,5 66 1 35

WAAS, EGNOS, QRZZ, GAGAN

NMEA 0183 V4.1 and backward compliance

-165

RF ANTENNA MODULE

Quectel Wireless Solutions

China http://www.quectel.com GNSS L16 GLONASS,GPS, Galileo ?, QZSS 3-3,6 UART SMD 1,5 32 2,5 35 WAAS,

EGNOS

NMEA 0183 Ver3.1

-162

LEADTEK China http://www.leadtek.com/eng/ LR9130 GPS 2,8-5 UART

I2C/SPI 2,5 48 2 35 NMEA-0183 -163

Maestro-Wireless China http://www.maestro-

wireless.com A5100-A

GPS / GLONASS concurrent GNSS module

SIRFSTAR V 3-3,6 UART 52 1 35 + NMEA -160