about SPP mode hangup problem

[akioolin]

Dear Sir:

the following code is what I used for send out data which captured from ADC via BT SPP. what I met problem is the data no longer send out after two times connect / disconnect from android BT serial terminal app. after put some debug code in loop(), I found after two times connect / disconnect, the data did'nt send out.
where is my missing point? if this a potential bug for real application or product prototyping?

Thanks in advance.

=============================================================
#include "BluetoothSerial.h"
#include "esp_bt_main.h"
#include "esp_bt_device.h"

#if !defined(CONFIG_BT_ENABLED) || !defined(CONFIG_BLUEDROID_ENABLED)
#error Bluetooth is not enabled! Please run make menuconfig to and enable it
#endif

#define LED_BUILTIN 22
#define DIST_SENSOR_PIN 33

#define uS_TO_S_FACTOR 1000000
#define DELAY_MS 10

typedef enum {
BT_UNKOWN = -1,
BT_DISCONNTECT = 0,
BT_CONNECTED = 1,
};

char sensor_name[16] = {0};
int bt_event_type = BT_UNKOWN;

BluetoothSerial SerialBT;

void callback(esp_spp_cb_event_t event, esp_spp_cb_param_t *param)
{
if (event == ESP_SPP_SRV_OPEN_EVT) {
Serial.println("Client Connected");
bt_event_type = BT_CONNECTED;
}

if (event == ESP_SPP_CLOSE_EVT ) {
Serial.println("Client disconnected");
bt_event_type = BT_DISCONNTECT;
}
}

bool initBluetooth()
{
if (!btStart()) {
Serial.println("Failed to initialize controller");
return false;
}

if (esp_bluedroid_init() != ESP_OK) {
Serial.println("Failed to initialize bluedroid");
return false;
}

if (esp_bluedroid_enable() != ESP_OK) {
Serial.println("Failed to enable bluedroid");
return false;
}

return true;
}

void printDeviceAddress()
{
const uint8_t* point = esp_bt_dev_get_address();

memset(sensor_name, 0x00, 16);
sprintf(sensor_name, "DIST_%02X%02X", point[4], point[5]);

for (int i = 0; i < 6; i++) {
char str[3];
sprintf(str, "%02X", (int)point[i]);
Serial.print(str);
if (i < 5) {
Serial.print(":");
}
}
Serial.println("");
Serial.println("");
}

// the setup function runs once when you press reset or power the board
void setup() {
pinMode(LED_BUILTIN, OUTPUT);
pinMode(DIST_SENSOR_PIN, INPUT);

Serial.begin(115200);

delay(100);
Serial.println("");

analogSetCycles(8);
analogSetSamples(2);
adcStart(DIST_SENSOR_PIN);
digitalWrite(LED_BUILTIN, LOW);

Serial.println("Distance Sensor V2.0");
Serial.println("");

initBluetooth();
printDeviceAddress();

SerialBT.begin(sensor_name);
SerialBT.register_callback(callback);
Serial.println(sensor_name);
bt_event_type = BT_DISCONNTECT;
}

// the loop function runs over and over again forever
void loop() {
int dist_val = 0;
unsigned long start_time = 0;
unsigned long stop_time = 0;
int diff_time = 0;

//start_time = millis();
digitalWrite(LED_BUILTIN, HIGH);

dist_val = analogRead(DIST_SENSOR_PIN);

diff_time = SerialBT.available();

if (bt_event_type == BT_CONNECTED) {
SerialBT.println(String(dist_val));
//} else if(bt_event_type == BT_DISCONNTECT) {
// Serial.println(String(dist_val));
//} else {
// Serial.println("no data");
}

Serial.println(String(dist_val) + " " + String(diff_time));

//stop_time = millis();
//diff_time = DELAY_MS - (stop_time - start_time);
//if (diff_time > 0) delay(diff_time);
delay(DELAY_MS);

digitalWrite(LED_BUILTIN, LOW);
delay(DELAY_MS);
}

BR, Akio