Argon BLE Syntax

Argon BLE Syntax

Overview

  • Present basic guide to receiving data from phone app to Argon
  • To simplify some of the code, we will be using a custom-built BLE library
  • For more in-depth information including sending from Argon and connecting to multiple devices

Receiving Data with Argon

void onDataReceived(const uint8_t* data, size_t len,
                    const BlePeerDevice& peer,void* context);
  • After a BLE connection is made, onDataReceived is the event handler that is called when data is received by the Argon
  • We are only concerned with the first two parameters: data and len

Receiving Data with Argon

  • const uint8_t* data
    • uint_8 is the variable type for unsigned byte (8 bits)
    • const uint8_t* is a pointer, which in C++ indicates the start of an array
    • data represents an array of bytes
  • size_t len represents the number of bytes that were received

Handling Pointers

  • Pointers are powerful, wonderful, and complex C++ tool
  • However, we are just going to treat data as an array

Example

  • Let’s say the onDataReceived parameter len equal 5

  • We can then treat the data variable as an array of bytes

    Serial.println("First element: " + String(data[0]));
  
uint8_t thirdByte = data[2];
  
uint8_t sixthByte = data[5];  //ERROR! len = 5; arrays start at 0

Bluefruit App

  • When sending data over Bluetooth, data will be packaged in bytes
  • It is important to know ahead of time the format of the data
  • We will be using Adafruit’s Bluefruit app to communicate with Argon
  • The data structure is specific to this app and doesn’t apply to other apps
  • For reference: Adafruit Bluefruit Guide

Bluefruit App Commands

  • Each command from the app is a series of bytes
    • IMPORTANT: char variables or single letters are also bytes
  • The first byte is the char of !
  • The second byte signals the type of command
  • For example
    • B means a button on the control pad was pressed
    • L means that location data from the phone is being send

Bluefruit App Control Pad

Bluefruit App Control Pad

  • Button presses send 5 bytes
[‘!’] [‘B’] [BUTTON_CODE] [BUTTON_STATE] [CRC]
  • BUTTON_CODE represents the symbol pressed (e.g. button was would be '1')
  • BUTTON_STATE represents if the button was pressed ('1') or released ('0')
  • CRC is an error-checking byte (we won’t worry about it for now)

Examples

  • Pressing the 3 button means that the data “array” would have the values
[‘!’] [‘B’] ['3'] ['1'] [CRC]
  • Releasing the Up arrow button means that the data “array” would have the values
[‘!’] [‘B’] ['5'] ['0'] [CRC]

Lab: Control Fan

  • Use Bluefruit app to control a DC motor and servo motor
  • Download starting code
    • Go to https://bit.ly/ProjectZip
    • Paste the following link into the top right https://github.com/reparke/ITP348-Physical-Computing/tree/main/_exercises/week09/ble_fan_start
  • In Bluefruit app, connect to over UART (listed as “controller”)

Lab Wiring Guide

On-board LED    D7
Servo           D2

Motor Controller
 PWMA           D5 
 AIN2           D4 
 AIN1           D3 
 VCC            3v3
 GND            GND
 VM             3v3
 STBY           3v3

servo_dc_fan_controller_bb

Lab: Control Fan (part 1)

  • Specifications
    • When “1” is pressed down, on-board LED D7 will blink twice
    • When “2” is pressed down, on-board LED D7 will turn on
    • When “2” is released, on-board LED D7 will turn off
  • Reference: Adafruit Bluefruit Guide

Lab: Control Fan (part 2)

  • Specifications
    • When “RIGHT” is pressed down, rotate servo (by fixed amount) clockwise
    • When “LEFT” is pressed down, rotate servo (by fixed amount) counter clockwise
    • When “UP” is pressed down, speed up motor (by fixed amount)
    • When “DOWN” is pressed down, slow motor(by fixed amount)
    • Optional challenge:
      • When “3” is pressed down, change direction of DC motor
      • When “4” is pressed, turn on fan auto mode
  • Reference: Adafruit Bluefruit Guide

Demo Projects

  • The following two completed projects are provided
  • Each involves using a phone app to communicate with Argon via Bluetooth
  • The coding in these examples is much more complicated than the previous exercises

Demo #1: Control RGB LED with Phone Accelerometers (part 1)

  • Use Bluefruit app to send accelerometer data from phone to Argon
  • Control RGB LED colors with accelerometer data
  • Download starting code
    • Go to https://bit.ly/ProjectZip
    • Paste the following link into the top right https://github.com/reparke/ITP348-Physical-Computing/tree/main/_exercises/week09/ble_uart_rgb_accel_example

Demo #1: Control RGB LED with Phone Accelerometers (part 2)

  • Using Bluefruit, connect to over UART (listed as “controller”) in app
  • Enable “accelerometer” in app
  • Argon sketch will receive accelerometer data (X, Y, Z) from phone, convert readings to PWM (0-255), and change LED color
  • Reference: Adafruit Bluefruit Guide

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Demo #2: Read Health Thermometer Service (part 1)

  • Send temperature data from Argon to phone via nRF Toolbox

  • Argon is using Bluetooth health thermometer service

  • Download starting code

    • Go to https://bit.ly/ProjectZip

    • Paste the following link into the top right https://github.com/reparke/ITP348-Physical-Computing/tree/main/_exercises/week09/ble_health_temp_final

Demo #2: Read Health Thermometer Service (part 2)

  • Using nRF Toolbox app, connect to over HTM (“health thermometer”)
  • Argon sketch will send temperature data to app
  • Reference: Particle Guide

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References

Credits

Updated: