scanner.ino File Reference

ESP32 BLE Central with RFID and LCD UI. More...

#include <Arduino.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/queue.h"
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEClient.h>
#include <BLEScan.h>
#include <LiquidCrystal_I2C.h>
#include <Wire.h>
#include <SPI.h>
#include <MFRC522.h>
#include "BLEScanner.h"
#include "distance.h"

Macros
#define	SERVICE_UUID   "275dc6e0-dff5-4b56-9af0-584a5768a02a"
#define	BUTTON_CHAR_UUID   "b51bd845-2910-4f84-b062-d297ed286b1f"
#define	IMU_CHAR_UUID   "0679c389-0d92-4604-aac4-664c43a51934"
#define	BUZZER_PIN   42
#define	RESET_PIN   41
#define	RFID_PIN   40
#define	PIN_SCK   13
#define	PIN_MISO   11
#define	PIN_MOSI   12
#define	PIN_SS   14
#define	PIN_RST   10

Functions
void	BLEScannerTask (void *pvParameters)
	Task to scan for BLE peripherals.
void	distanceTask (void *pvParameters)
	Task to compute distance from RSSI.
void	UITask (void *pvParameters)
	Task to update LCD UI.
void	buttonTask (void *pvParameters)
	Task to handle button input.
void	RFIDTask (void *pvParameters)
	Task to handle RFID scanning and authorization.
void	resetButtonTask (void *pvParameters)
	Task to reset RFID and lock system.
LiquidCrystal_I2C	lcd (0x27, 16, 2)
MFRC522	rfid (PIN_SS, PIN_RST)
bool	isAuthorized ()
	Check if RFID UID is authorized.
void	setup ()
	Arduino setup function. Initializes queues, peripherals, tasks, and starts FreeRTOS.

Variables
TaskHandle_t	UITaskHandle
TaskHandle_t	ButtonTaskHandle
TaskHandle_t	RFIDTaskHandle
QueueHandle_t	IMUQ
QueueHandle_t	RSSIQ
QueueHandle_t	disQ
QueueSetHandle_t	uiSet = nullptr
uint32_t	startTime
byte	AUTH_UID [] = { 0x04, 0x81, 0x70, 0x0A, 0x9C, 0x14, 0x90 }
	Authorized UID for RFID access.

Detailed Description

ESP32 BLE Central with RFID and LCD UI.

This sketch implements an ESP32 BLE central device that:

• Scans and connects to a BLE peripheral (with Button + IMU characteristics)
• Estimates distance from RSSI using a path-loss model
• Displays IMU movement state and distance on an I2C LCD
• Uses FreeRTOS tasks for concurrency (scanner, distance calc, UI, button, RFID, reset)
• Integrates RC522 RFID for access control, requiring authorized UID

Note

Uses ESP32 Arduino Core 3.x (NimBLE backend).

Author

George Evans Daenuwy & Rasya Fawwaz

Date

2025-08-21

Macro Definition Documentation

BUTTON_CHAR_UUID

#define BUTTON_CHAR_UUID   "b51bd845-2910-4f84-b062-d297ed286b1f"

Button characteristic UUID

BUZZER_PIN

#define BUZZER_PIN   42

GPIO pin for buzzer/button

IMU_CHAR_UUID

#define IMU_CHAR_UUID   "0679c389-0d92-4604-aac4-664c43a51934"

IMU characteristic UUID

PIN_MISO

#define PIN_MISO   11

RC522 MISO pin

PIN_MOSI

#define PIN_MOSI   12

RC522 MOSI pin

PIN_RST

#define PIN_RST   10

RC522 reset

PIN_SCK

#define PIN_SCK   13

RC522 SCK pin

PIN_SS

#define PIN_SS   14

RC522 chip select (SDA/SS)

RESET_PIN

#define RESET_PIN   41

GPIO pin for reset button

RFID_PIN

#define RFID_PIN   40

GPIO pin for RFID buzzer

SERVICE_UUID

#define SERVICE_UUID   "275dc6e0-dff5-4b56-9af0-584a5768a02a"

< BLE core (ESP32 Arduino core 3.x uses NimBLE backend) < I2C LCD library < I2C bus < SPI bus < RFID RC522 driver < Custom BLE scanning logic < Distance estimation from RSSI Service UUID

Function Documentation

BLEScannerTask()

void BLEScannerTask

(

void *

pvParameters

)

Task to scan for BLE peripherals.

BLE scanner task.

• Initializes BLE central
• Scans for peripherals advertising the target service UUID
• Connects and auto-reconnects if disconnected
• Periodically reads RSSI and sends to RSSI queue

buttonTask()

void buttonTask

(

void *

pvParameters

)

Task to handle button input.

Button task.

• Reads button press with debouncing
• Sends state via BLE

distanceTask()

void distanceTask

(

void *

pvParameters

)

Task to compute distance from RSSI.

Distance estimation task.

• Consumes RSSI values
• Smooths RSSI
• Converts to distance estimate
• Sends result to distance queue

isAuthorized()

bool isAuthorized

(

)

Check if RFID UID is authorized.

Return values

true	if UID matches AUTH_UID
false	otherwise

lcd()

LiquidCrystal_I2C lcd	(	0x27	,
		16	,
		2	)

I2C LCD (16x2)

resetButtonTask()

void resetButtonTask

(

void *

pvParameters

)

Task to reset RFID and lock system.

Reset button task.

• Debounced reset button input
• Resets RFID and locks system
• Suspends UI and button tasks

rfid()

MFRC522 rfid	(	PIN_SS	,
		PIN_RST	)

RFID reader instance

RFIDTask()

void RFIDTask

(

void *

pvParameters

)

Task to handle RFID scanning and authorization.

RFID task.

• Waits for RFID card
• Prints UID to Serial
• Grants access if authorized
• Resumes UI and button tasks on success

setup()

void setup

(

)

Arduino setup function. Initializes queues, peripherals, tasks, and starts FreeRTOS.

UITask()

void UITask

(

void *

pvParameters

)

Task to update LCD UI.

UI task.

• Displays distance and movement state on LCD
• Consumes from IMUQ and distance queue

Variable Documentation

AUTH_UID

byte AUTH_UID[] = { 0x04, 0x81, 0x70, 0x0A, 0x9C, 0x14, 0x90 }

Authorized UID for RFID access.

ButtonTaskHandle

TaskHandle_t ButtonTaskHandle

Handle for button task

disQ

QueueHandle_t disQ

Queue for distance values

IMUQ

QueueHandle_t IMUQ

Queue for IMU moving flag

RFIDTaskHandle

TaskHandle_t RFIDTaskHandle

Handle for RFID task

RSSIQ

QueueHandle_t RSSIQ

Queue for RSSI values

startTime

uint32_t startTime

Timer for RSSI sampling

uiSet

QueueSetHandle_t uiSet = nullptr

Queue set for UI multiplexing

UITaskHandle

TaskHandle_t UITaskHandle

Handle for UI task