Ping fluctuations

[podaen]

Board

DOIT ESP32 devkit v4

Device Description

N

Hardware Configuration

I2S audio output

Version

latest development Release Candidate (RC-X)

IDE Name

1.8.19

Operating System

windows10

Flash frequency

80MHz

PSRAM enabled

no

Upload speed

115200

Description

I am making a program that involves url audio streams and starting to notist that it starts fluctuating in filling the buffer.

By doing a ping test I see once the response start to be fluctuating above 200ms and it doesn't recover. And that is what I see in my stream too.

Can it not been made that the ping is not fluctuating so much?? I got this problem also in WiFiclient.h and WiFiClientSecure.h, but I think this is not where the issue is.

Sketch

/*ping test*/
#include "WiFi.h"
#include <esp_wifi.h>
#include <esp_bt_main.h>//power saving bluetooth
#include <esp_bt.h>//power saving bluetooth

const char* ssid = "SSID";
const char* password = "PASS";

void setup() {
    Serial.begin(115200);
    while (!Serial);
    WiFi.begin(ssid, password);

    while (WiFi.status() != WL_CONNECTED) {
        delay(1000);
        Serial.println("Connecting to WiFi..");
    }
    //esp_wifi_set_ps(WIFI_PS_NONE);
    WiFi.setSleep(false);

    esp_bluedroid_disable();
    esp_bluedroid_deinit();
    esp_bt_controller_disable();
    esp_bt_controller_deinit();

    Serial.println(WiFi.localIP());
    Serial.print("RSSI: ");
    Serial.println(WiFi.RSSI());//the closer to 0, the stronger the signal
}

// the loop function runs over and over again until power down or reset
void loop() {
  
}

/*speed test*/
//#include <HTTPClient.h>
//#include "WiFi.h"
//#include <esp_wifi.h>
//#include <esp_bt_main.h>//power saving bluetooth
//#include <esp_bt.h>//power saving bluetooth
//
//const char* ssid = "SSID";
//const char* password = "PASS";
//
//void setup() {
//    Serial.begin(115200);
//    WiFi.begin(ssid, password);
//
//    while (WiFi.status() != WL_CONNECTED) {
//        delay(1000);
//        Serial.println("Connecting to WiFi..");
//    }
//    esp_wifi_set_ps(WIFI_PS_NONE);
//    WiFi.setSleep(false);
//
//        esp_bluedroid_disable();
//    esp_bluedroid_deinit();
//    esp_bt_controller_disable();
//    esp_bt_controller_deinit();
//
//    Serial.println(WiFi.localIP());
//    Serial.print("RSSI: ");
//    Serial.println(WiFi.RSSI());//the closer to 0, the stronger the signal
//}
//
//long speedtest() {
//    unsigned long start;
//    long total = 0;
//    if ((WiFi.status() == WL_CONNECTED)) { //Check the current connection status
//
//        HTTPClient http;
//        //Serial.print("starting...");
//        //http.begin("https://proof.ovh.net/files/1Mb.dat", root_ca); //Specify the URL and certificate
//        http.begin("http://speedtest.tele2.net/1MB.zip"); //Specify the URL and certificate
//        int httpCode = http.GET();                                                  //Make the request
//
//        if (httpCode > 0) { //Check for the returning code
//            //Serial.print(httpCode); Serial.print("           ");
//            if (httpCode == HTTP_CODE_OK) {
//                // get length of document (is -1 when Server sends no Content-Length header)
//                total = http.getSize();
//
//                uint8_t buff[512] = { 0 };
//                int buf_size_actual = sizeof(buff);
//                Serial.print("Buff Size: "); Serial.print(buf_size_actual);
//                WiFiClient* stream = http.getStreamPtr();
//                http.setReuse(true);
//                start = millis();
//                size_t size = 1;
//                long remaining = total;
//                while (http.connected() && (remaining > 0 || remaining == -1)) {
//                    if (stream->available()) {
//                        remaining -= stream->readBytes(buff, 512);
//                    }
//                }
//            }
//        }
//        else {
//            Serial.println("Error on HTTP request");
//        }
//
//        http.end();
//        Serial.print("\tTime: "); Serial.print(millis() - start);
//        Serial.print("\tBytes: "); Serial.print(total);
//        Serial.print("\tThroughput :"); Serial.print("\t"); Serial.print(total / (millis() - start) * 8); Serial.print("\tkbps");
//        return total / (millis() - start) * 8;
//        Serial.println("");
//    }
//}
//
//void loop() {
//    Serial.println(speedtest());
//    delay(5000);
//}

Debug Message

This is a few tests I did, but it is not the worst case scenario. When it gets bad it get above 200ms, I see this once but I forgot the copy. 

> Pingen naar 192.168.1.178 met 512 bytes aan gegevens:
> Antwoord van 192.168.1.178: bytes=512 tijd=935 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=10 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=11 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=10 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=12 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=9 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
4ms against 12ms +200%

> Antwoord van 192.168.1.178: bytes=512 tijd=16 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=10 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=9 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=11 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=9 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=10 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=9 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
5ms against 11ms +100%

> Antwoord van 192.168.1.178: bytes=512 tijd=41 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=10 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=10 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=9 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=24 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=9 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=10 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
> Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
4ms against 24ms 500%

without setSleep(false) and ble disable
Antwoord van 192.168.1.178: bytes=512 tijd=115 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=129 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=55 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=73 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=110 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=121 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=28 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=64 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=99 ms TTL=255
Time-out bij opdracht.
Antwoord van 192.168.1.178: bytes=512 tijd=54 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=78 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=94 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=106 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=42 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=62 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=85 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=113 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=27 ms TTL=255
5ms against 106ms 2000%

connection speed (with an rssi -62 (with antenna) -> +-1300kbs???)
Buff Size: 512 Time: 7142 Bytes: 1048576 Throughput : 1168 kbps1168
Buff Size: 512 Time: 8244 Bytes: 1048576 Throughput : 1016 kbps1016
Buff Size: 512 Time: 6870 Bytes: 1048576 Throughput : 1216 kbps1216
Buff Size: 512 Time: 6739 Bytes: 1048576 Throughput : 1240 kbps1240
Buff Size: 512 Time: 6360 Bytes: 1048576 Throughput : 1312 kbps1312
Buff Size: 512 Time: 6800 Bytes: 1048576 Throughput : 1232 kbps1232
Buff Size: 512 Time: 6645 Bytes: 1048576 Throughput : 1256 kbps1256
Buff Size: 512 Time: 7924 Bytes: 1048576 Throughput : 1056 kbps1056
Buff Size: 512 Time: 6241 Bytes: 1048576 Throughput : 1344 kbps1344
Buff Size: 512 Time: 6324 Bytes: 1048576 Throughput : 1320 kbps1320
Buff Size: 512 Time: 7214 Bytes: 1048576 Throughput : 1160 kbps1160
Buff Size: 512 Time: 7879 Bytes: 1048576 Throughput : 1064 kbps1064
Buff Size: 512 Time: 6289 Bytes: 1048576 Throughput : 1328 kbps1328
Buff Size: 512 Time: 6145 Bytes: 1048576 Throughput : 1360 kbps1360
Buff Size: 512 Time: 6253 Bytes: 1048576 Throughput : 1336 kbps1336
Buff Size: 512 Time: 6421 Bytes: 1048576 Throughput : 1304 kbps1304
Buff Size: 512 Time: 6192 Bytes: 1048576 Throughput : 1352 kbps1352
Buff Size: 512 Time: 6119 Bytes: 1048576 Throughput : 1368 kbps1368
Buff Size: 512 Time: 6440 Bytes: 1048576 Throughput : 1296 kbps1296

Other Steps to Reproduce

See also
pschatzmann/arduino-audio-tools#180

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[podaen]

After my search I came out here WiFiGeneric.cpp, I'm thinking of a memory problem and maybe caused by a timout.

[podaen]

When I run WiFi on core 0 the fluctuate sooner bigger. And than it stabilizes and than pops up much bigger, but less over time.

I tried with these settings too

esp_wifi_set_mode(WIFI_MODE_NULL);
WiFi.useStaticBuffers(true);

it stills occur.

Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=9 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=8 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=666 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=140 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=629 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=7 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=5 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=6 ms TTL=255
Antwoord van 192.168.1.178: bytes=512 tijd=4 ms TTL=255

[podaen]

I set the log to verbose, nothing is shown.

I found this about how wifi works

And than I cam out here that includes FreeRTOS

The task of the event running on the same core as the task I am running, during selecting core0 a see a difference in timing.

[podaen]

It have to be something that is running in the background and runs on core0. Why could it be that if the WiFi runs on an other core and the breaks get soo long above the 200. It even cuts the data off from a stream (core independent), but the clock keeps running.

[podaen]

I m ended in FreeRTOS. This is called form the ESP and I think that the buffer takes longer than expected to allocated in to the memory, because something else is called that takes long... or it want to take the same place. And because there is data been lost, I think it's the place that has been taken. There most be priority for the buffer! Anyway that memory has to be preserved for the buffer.

There is something I have done and that is serial... Which can not be turned off, but it's a start. The serial monitor works for both cores and ends up one pin gpio 3. And if we run the wifi on core0 it need to switch from core0 to core1.

it starts to make sens now. It more constant, but when it happens it get more clear.

[podaen]

I have set WIFI_TASK_CORE_ID to 1 in esp_wifi.h, task in to 0. The biggest number I ever had is 81ms, The varriation could be 23ms. but that is not in the standaard deviation, that is normaly around 9ms. I diden't measure the beginnings because the doesn't count for me. I think this is the best number I ever had.

By setting my task to core0 and set the WIFI_TASK_CORE_ID to 0 I get a corrupted backtrace after a few package received. So I changing back to default. Now strang things happens...

Task core1
WiFi core1

199ms at most, verry bad setting

Task core1 (default)
Wfii core0 (default, but with a task)

I cot a corruped backtrace (few package received and crash)

Task core0
WiFi core1

I got a corruped backtrace (few package received and crash)

Task core 0
WiFi core 0

I got a corruped backtrace (few package received and crash)

Task core 0
WiFi core 1

78ms at most.

Task core 1
WiFi core 0

169ms at most

Note: the package where still sending when I changed the settings uploaded and rebooted. I did changed the setting in the library it self and diden't set CONFIG_ESP32_WIFI_TASK_PINNED_TO_CORE_1. This can be the causes the corrupted backtracé. If I set it in to my sketch it doesn't recognize it and esp_wifi_init. If somebody know how to do it, I would be glad to know!

The UART running on to the default core. And the something that triggers FreeTROS to put UART information from core0 in to core1. Still the antenna is not only receiving data but is also transmitting data. Switching between transmitting and receiving happens really fast if the transmitting is not the same amount data than the receiving, like most cases (including mine).

What I do see as that switching between cores doesn't go that fast.

Thing to do: Test a connection without DHCP.

[Jason2866]

I always wondered why the ping times for the ESP32 is in general higher as for ESP32-S2, S3 and C3.
My wild guess the two cores and wifi switching has a general problem "somewhere".

[podaen]

The probebly have a beter design, but I m curious... Could you try the shetch, let it run for 10 min and and post your worst results?

[podaen]

The UART running on to the default core. And the something that triggers FreeTROS to put UART information from core0 in to core1. Still the antenna is not only receiving data but is also transmitting data. Switching between transmitting and receiving happens really fast if the transmitting is not the same amount data than the receiving, like most cases (including mine).

Further test with the esp32 devkit tells me that the urart not causing this breaks.

I m testing now my stream, and it still breaks with loop core0 and WiFi_event to core1, so 60ms is still to much. But it doesn't cuttoff anymore. That's a good thing.

For me it's clear that the software is the solution to solve this... Still wondering why I can't set the loop and the event on the same core, core0. If I would have less than 16ms for every package, I think it would work.

[podaen]

Spoken to soon, it still breaks. Probably on the 60ms, because the occure after a couple minuts. It is like it running out of sync...

[podaen]

This surprises me in the WiFiGeneric.h...

static void _arduino_event_task(void * arg){
	arduino_event_t *data = NULL;
    for (;;) {
        if(xQueueReceive(_arduino_event_queue, &data, portMAX_DELAY) == pdTRUE){
            WiFiGenericClass::_eventCallback(data);
            free(data);
            data = NULL;
        }
    }
    vTaskDelete(NULL);
    _arduino_event_task_handle = NULL;
}

Why deleting it, when the connection is still open?

[podaen]

Ok, I did some measurement. It doesn't take time to create a task a task on a other core and it doesn't take time to delete a task.

@Jason2866 My mistake, switching cores doesn't take time. If you say that an S doesn't have that issue. than it could be board driver related, but we be still not sure. wifi is under 2.0.3-RC1\tools\sdk\esp32\include\esp_wifi\include. other board other esp_wifi.

Mistery unsolved

[podaen]

what does that mean, flight time? I looked it up and it says that is a distance sensor... Not impotent for this topic.