Project embeddedSystemDesign2

Project-LabEmbeddedDesign2

This repository contains the presentation, reports and code for the project constructed for Embedded System Design 2 - Lab.

1 - Quick links

• Reports and presentation
• General important Doxygen documentation
• Doxygen code documentation of individual files and methods
• Code for the custom TTN decoder
• Schematic of custom PCB
• Schematic of DRAMCO LoRaWAN shield
• Picture with PCB dimensions
• The Things Network - Applications
• Cayenne Dashboard

2 - GIT repo structure

3 - Code flow

Note: The code is developed using Simplicity Studio v4 on Ubuntu 18.04 LTS. The code also has dbprint functionality.

Extra notes on the flowchart:

• (*1): The following things get initialized:
  • Chip
  • GPIO wakeup (buttons & ADXL INT1)
  • ADC
  • Disable RN2483
  • Accelerometer (initialize SPI and use it to configure the accelerometer
• (*2): On every external temperature measurement the VDD and DATA pin get re-configured. The oneWire protocol is achieved using bit-banging.
• (*3): The RN2483 module gets enabled and configured before sending the data. Afterwards it gets disabled again. The status message is always send, measurements only if there are any recorded.
• (*4): Only one set of measurements are send along with the status message.
• (*5): The value of X depends on a configured setting.
• (*6): A status message is send along with any recorded measurements.

• Before entering a sleep state all GPIO (data) pins are disabled so they can't consume any power.
• Clocks and peripherals are only enabled when necessary.
• If an error occures this gets forwarded to the cloud using a LoRaWAN status message.
• To conserve sended bytes a custom data-format was used (along with a decoder).
• Negative internal and external temperatures were successfully send and displayed. The internal temperature seems to be 2 - 3 °C off.

4 - Extra hardware changes

The schematic for the custom PCB misses two resistors. A surface mount 10 kΩ resistor was added between the data and power pin for the DS18B20 temperature sensor. A 3,3 kΩ resistor with wires was added between the BREAK_1pin and VDD. These added resistors can be seen on the bottom right on the left most picture below.

An SMA connector for an external antenna was also added to the DRAMCO LoRaWAN shield. This was done by removing the chip-antenna, capacitors C3 and C4 and inductor L1 and replacing it with an SMA connector directly connected to the signal pin of the RN2483 module. This modification can be seen on the right on the right most picture above.

To protect the PCB's from moisture and other contaminants, they were given 2 coats of PLASTIK 70.