eGuard_octa

More information about the backend in the eGuard_backend folder.

About

The eGuard is a device which tracks the health of an electronic device by using sensors like an accelerometer, a light sensor, a temperature and humidity sensor, ...

While programming, we paid attention to the low power aspect which is needed in the world of IoT to let devices run several years on a single battery.

Information

University of Antwerp

Course: I-IoT Low Power Embedded Systems

Professsor/teacher: Maarten Weyn, Michiel Aernouts, Mats De Meyer

Master Students: Thomas Verellen, Robin Janssens, Toon De Keyzer

Setup

If the eGuard is inside (determined with DASH7 connection), it will use DASH7 to communicate and fingerprinting to locate itself in the class room. When outside, the eGuard will automatically switch to LoRaWAN to communicate with the backend and use the GPS module to locate itself.

In the current version, the switch between DASH7 vs. LoRaWAN and GPS is done by pressing BTN1 to illustrate the operation.

Programming Environment

• Vagrant
• RIOT OS

Hardware eGuard

• Nucleo L496ZG (white)
• Octa connect shield (black)
• Octa connect Murata modem shield (blue)
• Octa connnect GPS shield (green)

Backend

• MongoDB
• Fingerprinting
• MQTT broker
• The Things Network
• Thingsboard
• Telegram Push Notifications

Deploy

Hardware

• Octa Board
  • Mount the Murata modem shield on P1
  • Mount the GPS shield on P2

Keys

• Add your device's ABP keys to template_keys.h and rename this file to keys.h

Drivers

• This repository uses newly made drivers. To install these, correctly place the following files in the corresponding folders:

  • Move the .h files in drivers/include/ to RIOTBASE/drivers/include/
  • Move the folders with .c files in drivers/drivers/ to RIOTBASE/drivers/

• Edit the RIOTBASE/drivers/Makefile.dep file and add the following code:

ifneq (,$(filter lsm303agr,$(USEMODULE)))
  FEATURES_REQUIRED += periph_i2c
endif

ifneq (,$(filter xm1110, $(USEMODULE)))
  USEMODULE += xtimer
  FEATURES_REQUIRED += periph_i2c
endif

ifneq (,$(filter tcs34725,$(USEMODULE)))
  FEATURES_REQUIRED += periph_i2c
endif

• Edit the RIOTBASE/drivers/Makefile.include file and add the following code:

ifneq (,$(filter lsm303agr,$(USEMODULE)))
  USEMODULE_INCLUDES += $(RIOTBASE)/drivers/lsm303agr/include
endif

ifneq (,$(filter xm1110,$(USEMODULE)))
  USEMODULE_INCLUDES += $(RIOTBASE)/drivers/xm1110/include
endif

ifneq (,$(filter tcs34725,$(USEMODULE)))
  USEMODULE_INCLUDES += $(RIOTBASE)/drivers/tcs34725/include
endif

I2C configuration

• Edit the RIOTBASE/boards/octa/include/periph_conf.h file en replace the I2C-config with the following:

static const i2c_conf_t i2c_config[] = {
    {
        .dev            = I2C1,
        .speed          = I2C_SPEED_NORMAL,
        .scl_pin        = GPIO_PIN(PORT_B, 8),
        .sda_pin        = GPIO_PIN(PORT_B, 9),
        .scl_af         = GPIO_AF4,
        .sda_af         = GPIO_AF4,
        .bus            = APB1,
        .rcc_mask       = RCC_APB1ENR1_I2C1EN,
        .irqn           = I2C1_EV_IRQn
    },
    {
        .dev            = I2C2,
        .speed          = I2C_SPEED_NORMAL,
        .scl_pin        = GPIO_PIN(PORT_F, 0),
        .sda_pin        = GPIO_PIN(PORT_F, 1),
        .scl_af         = GPIO_AF4,
        .sda_af         = GPIO_AF4,
        .bus            = APB1,
        .rcc_mask       = RCC_APB1ENR1_I2C2EN,
        .irqn           = I2C2_EV_IRQn
    }
};

Components/Techniques

GPS

General

The global (outdoor) position of the eGuard is determined by two variables; latitude and longitude. These variables represent the position on the earth.

GPS data is presented in NMEA data. NMEA data can have different formats for different kinds of data. Basically, it consists of structured characters. Data is kept in the buffer (255 bytes) of the GPS module. We can read the data from the buffer sequentially through I2C.

When data is retrieved, it can be parsed to obtain the coordinates. We will use minmea because it was already integrated in RIOT OS. We chose to parse NMEA data in the RMC format (Recommended Minimum Data for gps), which looks like the following.

$GNRMC,105824.000,A,5110.577055,N,00420.844651,E,0.42,285.58,080119,,,A*73

We discard all the other NMEA data.

The data fiels are seperated using a comma. These are the fields:

• 1st field defines the format
• 2nd field defines the time the fix is taken (UTC time)
• 3rd field defines the status (Active or Void)
• 4th field defines latitude
• 5th field defines longitude
• 6th field defines speed (knots)
• 7th field defines track angle
• 8th field defines the date
• 9th field defines the magnetic variation in degrees
• 10th field defines the checksum data, always begins with *

After reading through I2C and parsing the data, we send the latitude and longitude via LoRaWAN to the backend.

Low Power Aspect

Currently, the GPS module has a function to put the GNSS module in standby mode which operates correctly, but the wakeup function does not work. To wake up the GNSS module, a random byte has to be sent to the module. After testing, waking up the device did not work.

For this reason, the GPS is still always on.

Temperature/humidity sensor

The driver for the sht3x has been rewritten to support the integrated alarm mode. This makes it possible for the board to enter sleep mode and wake up by an interrupt driven by the temperature sensor. However, this was not used in the final application since we periodically wake up the board every 15 minutes. This means that for our appplication it would require less power to use the sensor in single shot mode and manually check if certain temperature or humidity borders are crossed.

Accelerometer

The driver for the accelerometer is based on the already existing lsm303dlhc. Furthermore, support for the free fall detection has been added to detect falls from 10 cm, 40 cm or 90 cm. Support for the low power mode of the sensor has not been added since this is only of interest when using the lsm303agr on a frequency higher than 10Hz. 10Hz suffices for our application.

Indoor localization using Fingerprinting

The firmware used to compose the fingerprint dataset can be found in the training branch. After a press on B1 it will send a predefined amount of messages on Dash-7 which can be collected on the backend.

Power Measurement

The application was written with low power usage in mind. The different components were used in such a way that the least amount of power is required.

• SHT3X: Used in single shot mode, one measurement every 15 minutes.
• LSM303AGR: Used in 10Hz continous mode.
• XM1110: The GPS sensor is not yet optimized for low power use. It is continously operating.
• MURATA: The communication module automatically goes into idle mode when not in use. However, the used driver keeps the LED on at all times, generating a high idle current.
• STM32L496ZGT6P: The used board has no support for low power mode in RIOT OS yet.

Division Of Labour

Thomas

• Drivers sensors (sht3x/ lsm303agr)
• ISR
• Power Measuring

Robin

• Backend
• Indoor Localization

Toon

• GPS