ESP32 BLE Communication

CETech May 18.2022

0 48997 Easy

In this project, We Will show you how to use BLE communication in ESP32 Controllers.

Hey, what's up, Guys! Akarsh here from CETech.

In this tutorial, I'm going to show you how to trigger actions with Bluetooth using M5Stamp PICO and M5Stick C which are very cheap and High efficient ESP32 Controllers.

We will create a simple Transmitter Receiver pair using M5Stick C and M5Stamp PICO modules and whenever we will trigger the connection using a button on M5Stick C, an LED will blink on the M5Stamp showing that it has received the Signal. We will be using Arduino IDE to program these modules as Transmitter and Receiver So you can also check using the Serial Monitor whether the Transmission is happening or not.

It is a very simple project and no Hardware connections are required as such. We just need to program the boards and we are good to go. So let's jump straight into it.

Things used in the project :

M5Stick C

M5Stamp PICO

Arduino IDE

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What are M5Stick and M5Stamp?

M5Stack is a technology company that designs and manufactures an open-source development toolkit, including hardware, programming platform, and IoT solutions. It was founded by Jimmy Lai in 2017 and is based in Shenzhen, China.

M5Stack created the M5Stick and M5Stamps, which are both based on the ESP32 controller. The M5Stick C features an embedded TFT display and battery, while the M5Stamp has a small footprint and can be used in a variety of IoT products.

M5StickC is a mini M5Stack, powered by ESP32. It is a portable, easy-to-use, open-source, IoT development board. It is an ESP32 development board with 0.96 inch TFT color screen (80 * 160 resolution), Red LED, button, Microphone, IR transmitter, 6-axis IMU (SH200Q), and 80 mAH battery. The ESP32 module ESP32-Pico in M5StickC also has a built-in 4MB flash. If the M5StickC is equipped with a watch base and watch belt, you can wear it on your wrist.

It is built in a continually growing hardware and software ecosystem. It has a lot of compatible modules and units, as well as the open-source code & engineering communities that will help you maximize your benefits in every step of the developing process.

Power switch operation:

Power on: Press the power button for 2 seconds

Power off: Press the power button for 6 seconds

The input range of VBUS_VIN and VBUS_USB is limited to 4.8-5.5V, and the internal battery will be charged through AXP192 power management when VBUS is powered.

STAMP-PICO features an ultra-compact design with two low-power Xtensa® 32-bit LX6 microprocessors at 240MHz on a PCB as tiny and delicate as a postage stamp. low power consumption. It is ideal for any space-constrained or battery-powered devices such as wearables, medical devices, sensors, and other IoT devices.

1, MULTIFORM: 5 options of installation, means endless possibilities! (SMT, DIP, flywire, grove interface), with a high-temperature resistant plastic shell, 3D antenna and components can be better protected.

2, LOW-CODE DEVELOPMENT: STAMP-PICO supports UIFlow graphical programming platform, scripting-free, cloud push; and fully compatible with Arduino, MicroPython, ESP32-IDF, and other mainstream development platforms to quickly build various applications.

3, HIGH INTEGRATION: STAMP-PICO contains a 5V->3.3V DC/DC port, GPIOx12, programmable RGB light x1, button x1, and finely tuned RF circuit, providing stable and reliable wireless communication.

4, STRONG EXPANDABILITY: Easy access to M5Stack's hardware and software ecology system: a wealth of sensors, actuators, functional modules, and accessories to choose from, and Extremely fast adaptation.

Set up M5Stamp and M5Stick with Arduino IDE by following these instructions.

https://docs.m5stack.com/en/quick_start/m5core/arduino

Flow :

M5Stick C will act as a BLE transmitter, while M5Stamp PICO will act as a BLE receiver. When Button A on the M5Stick is pressed, the M5Stamp's LED turns green.

Code for Transmitter:

The code for the Transmitter is as given below. You need to upload the code to the M5Stick C Controller using Arduino IDE. You can also access the code through the Github link provided here.

CODE

#include <M5StickC.h>
#include "BLEDevice.h"
#include "BLEUtils.h"
#include "BLEServer.h"
#include "BLEBeacon.h"

BLEAdvertising *pAdvertising;   // BLE Advertisement type
struct timeval now;
#define GPIO_DEEP_SLEEP_DURATION     1  // sleep x seconds and then wake up
RTC_DATA_ATTR static time_t last;        // remember last boot in RTC Memory
RTC_DATA_ATTR static uint32_t bootcount; // remember number of boots in RTC Memory
#define BEACON_UUID "87b99b2c-90fd-11e9-bc42-526af7764f64" // UUID 1 128-Bit (may use linux tool uuidgen or random numbers via https://www.uuidgenerator.net/)
void setBeacon()
{

  BLEBeacon oBeacon = BLEBeacon();
  oBeacon.setManufacturerId(0x4C00); 
  oBeacon.setProximityUUID(BLEUUID(BEACON_UUID));
  oBeacon.setMajor((bootcount & 0xFFFF0000) >> 16);
  oBeacon.setMinor(bootcount & 0xFFFF);
  BLEAdvertisementData oAdvertisementData = BLEAdvertisementData();
  BLEAdvertisementData oScanResponseData = BLEAdvertisementData();

  oAdvertisementData.setFlags(0x04); // BR_EDR_NOT_SUPPORTED 0x04

  std::string strServiceData = "";

  strServiceData += (char)26;     // Len
  strServiceData += (char)0xFF;   // Type
  strServiceData += oBeacon.getData();
  oAdvertisementData.addData(strServiceData);

  pAdvertising->setAdvertisementData(oAdvertisementData);
  pAdvertising->setScanResponseData(oScanResponseData);
}

void setup() {
  M5.begin();
  Serial.begin(115200);
  M5.Lcd.setTextColor(YELLOW);  //Set the font color to yellow.  设置字体颜色为黄色
  M5.Lcd.setRotation(3);
  M5.Axp.ScreenBreath(10);
  M5.Lcd.setTextColor(RED);
  M5.Lcd.setCursor(3, 10);
  M5.Lcd.setTextSize(2);
}

void loop() {

  M5.update();
  M5.Lcd.setCursor(3, 10);
  if (M5.BtnA.wasReleased()) {
    M5.Lcd.setTextColor(GREEN);
    M5.Lcd.println("Triggred");
    Serial.println("Trigger mode");
    // Create the BLE Device
    BLEDevice::init("BLE Receiver 01");
    // Create the BLE Server
    BLEServer *pServer = BLEDevice::createServer(); // <-- no longer required to instantiate BLEServer, less flash and ram usage
    pAdvertising = BLEDevice::getAdvertising();
    BLEDevice::startAdvertising();
    setBeacon();
    // Start advertising
    pAdvertising->start();
    Serial.println("Advertizing started...");
    delay(1000);
    pAdvertising->stop();
    M5.Lcd.fillScreen(BLACK);  
    M5.Lcd.setCursor(3, 10);
  } 
  }

Code for Receiver:

The code that is to be uploaded to the M5Stamp is as given below. You can also access the code through Github from here. You need to upload this code to M5Stamp using Arduino IDE.

CODE

#include "Arduino.h"
#include <FastLED.h>
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEScan.h>
#include <BLEAdvertisedDevice.h>

// How many leds in your strip?
#define NUM_LEDS 1
#define DATA_PIN 27

// Define the array of leds
CRGB leds[NUM_LEDS];

String knownBLEAddresses[] = {"24:a1:60:53:06:3e"};
int RSSI_THRESHOLD = -100;
bool device_found;
int scanTime = 1; //In seconds
BLEScan* pBLEScan;
class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
    void onResult(BLEAdvertisedDevice advertisedDevice) {
      for (int i = 0; i < (sizeof(knownBLEAddresses) / sizeof(knownBLEAddresses[0])); i++)
      {
        if (strcmp(advertisedDevice.getAddress().toString().c_str(), knownBLEAddresses[i].c_str()) == 0)
        {
          device_found = true;
          break;
        }
        else
          device_found = false;
      }
      Serial.printf("Advertised Device: %s \n", advertisedDevice.toString().c_str());
    }
};
void setup() {
  Serial.begin(115200); //Enable UART on ESP32
  FastLED.addLeds<SK6812, DATA_PIN, RGB>(leds, NUM_LEDS);  // GRB ordering is typical
  Serial.println("Scanning..."); // Print Scanning
  BLEDevice::init("");
  pBLEScan = BLEDevice::getScan(); //create new scan
  pBLEScan->setAdvertisedDeviceCallbacks(new MyAdvertisedDeviceCallbacks()); //Init Callback Function
  pBLEScan->setActiveScan(true); //active scan uses more power, but get results faster
  pBLEScan->setInterval(100); // set Scan interval
  pBLEScan->setWindow(99);  // less or equal setInterval value
}
void loop()
{
  BLEScanResults foundDevices = pBLEScan->start(scanTime, false);

  for (int i = 0; i < foundDevices.getCount(); i++)
  {
    BLEAdvertisedDevice device = foundDevices.getDevice(i);
    int rssi = device.getRSSI();
    Serial.print("RSSI: ");
    Serial.println(rssi);
    if (rssi > RSSI_THRESHOLD && device_found == true)
    {
      Serial.println("Triggred");
      leds[0] = 0xf00000;
      FastLED.show();
      delay(200);
    }

  }
  // Now turn the LED off, then pause
  leds[0] = 0x00f000;
  FastLED.show();
  delay(200);
  pBLEScan->clearResults();   // delete results fromBLEScan buffer to release memory
}

One thing that needs to be taken care of is that in this code, you need to provide the BLE Address of your MStickC. So change the field accordingly in the code.

Outcome:

Once the Transmitter and Receiver codes have been uploaded to the M5Stick and M5Stamp, connect the M5Stamp to your PC and open the serial monitor, then click the button A on the M5Stick C, which will display Triggered on the TFT Display.