loqoman/ripelockerble

Code and Design Documentation for RipeLocker's In-Chamber BLE Measurement Device.

RipeLockerBLE

Introduction

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RipeLockerBLE is a research embedded design project done by Darwin Clark during the summer of 2021 for RipeLocker LLC. The goal of this project was primarily to act as real-world design experience, however it also showed an alternative design path to solve similar power and communication requirements.

A Full-System View

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Full-System Overview Flowchat V2

Individual Modules

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Client (I.E Server) (What goes outside the chamber)

• The part that controls the periphral

Charateristics

• Always on
  • Radio is always on
  • CPU is always on
• Has constant conncetion to the RaspberryPi (working name for the device controlling the client)

Serial Control of the Client

Debugging Assuming that the assoicated control program / setup is on the fritz, a more bare-bones control scheme can be used with the linux tool screen. With the client board plugged into the Raspberry Pi via USB, running the following command will open a terminal emulation of the serial port.

screen /dev/ttyUSB0 115200

From there, messages can be simply typed into the terminal to be sent to the client. There are a couple of caviats to this however: - The default timeout for screen may inturrupt you when typing mid-message, resulting in a botched message to the client -

Peripheral (What goes IN the chamber)

• Connected to the MODBUS chip.
• Required to sleep for extended periods of time

Message Liberary

Order of Operations

1. Client scans for BLE beacons with the bleUART service
2. Client makes contact (connect()) with the peripheral
3. Client logs the connection
4. Client sends required messages to peripheral
   • (Sample Message Order)
   1. KEEPALIVE
   2. REQBATT
   3. REQREAD
   4. SETSLEEPTIME
   5. GOTOSLEEP
5. Peripheral disconnects from client
6. Client continues to active scan waiting for peripheral to wake up

Types of Messages

• Set Next Wakeup
  • Sets the time that will be used in the softwareTimer() inturrupt once the peripheral receives the "Go to Sleep" message
• Keep Alive
  • Just exists to see if there is someone on the other end. Acts as a verifcation of the Message format.
• Request for Reading
  • Asking the peripheral for the current reading from the peripheral
• Request Battery life
  • Asking the peripheral for the current estimated battery life
• Request Time of Transit
  • Sending a time to the peripheral
  • Asking the peripheral to reutrn the time of travel for the message
  • This message will likely be collated with the "Keep Alive" message
• Go to Sleep
  • Instructus the peripheral that there is no more information needed, and to re-enter a sleep mode.
    • N.B, "Go to Sleep" is different from "Set Next Wakeup

Code

Formatting

The codebase employs the following formatting decisions:

• Tabs: 4 spaces
• Brackets: Same line