ESP32-C3 BLE HID Device Not Visible on Mobile

[Martin L. (tempusertempuser)]

Hello everyone,

I’m working on a BLE HID project with an ESP32-C3 using the 
NimBLE-Arduino library. The goal is to make the ESP32 act as a BLE media 
remote (sending Play/Pause commands).

The code compiles and runs without errors in PlatformIO, but here’s the 
problem:

On my Android phone (Samsung A32), I cannot see the ESP32 device in the 
Bluetooth list.

I am advertising the HID service properly:

pAdvertising->addServiceUUID(hid->getHidService()->getUUID());
pAdvertising->start();

I’m using a minimal HID report map for Play/Pause.

Here is my code

#include <NimBLEDevice.h>
#include <NimBLEHIDDevice.h>
#include <HIDTypes.h>

NimBLEHIDDevice* hid;
BLECharacteristic* input;
bool sent = false;

void setup() {
    Serial.begin(115200);
    NimBLEDevice::init("ESP32-C3 Media Remote");

    NimBLEServer* pServer = NimBLEDevice::createServer();
    hid = new NimBLEHIDDevice(pServer);

    input = hid->getInputReport(1);

    hid->setManufacturer("MyManufacturer");
    hid->setPnp(0x02, 0xe502, 0xa111, 0x0210);
    hid->setHidInfo(0x00, 0x01);

    hid->setReportMap((uint8_t*)reportMap, sizeof(reportMap));
    hid->startServices();

    NimBLEAdvertising* pAdvertising = NimBLEDevice::getAdvertising();
    pAdvertising->setAppearance(HID_KEYBOARD);
    pAdvertising->addServiceUUID(hid->getHidService()->getUUID());
    pAdvertising->start();

    Serial.println("BLE Media Remote ready!");
}

void loop() {
    if (!sent && NimBLEDevice::getServer()->getConnectedCount() > 0) {
        Serial.println("Sending Play/Pause...");

        uint8_t press[1] = {0x01};   // press Play/Pause
        input->setValue(press, sizeof(press));
        input->notify();
        delay(100);

        uint8_t release[1] = {0x00}; // release key
        input->setValue(release, sizeof(release));
        input->notify();

        sent = true;
    }
}

I’ve tried:

Restarting the phone and ESP32

Using different BLE scanning apps like nRF Connect

Checking that the ESP32 is powered and advertising

But my phone still doesn’t detect it.

Questions:

Are there any specific settings required to make an ESP32-C3 BLE HID 
visible to mobile devices?

Could this be a compatibility issue with certain phones?

Any tips for debugging BLE advertising issues on ESP32-C3?

Thanks in advance for any guidance!

[Alexander (alecxs)]

Martin L. schrieb:
> Could this be a compatibility issue with certain phones?

Yes, but more likely with ancient phones. Samsung Galaxy A32 supports 
BLE 5.0

[Alexander (alecxs)]

It's unclear what IDE you're using. The code looks like Arduino. Did you 
manage to run PlatformIO on Arduino Core, pioarduino?

Martin L. schrieb:
> The code compiles and runs without errors in PlatformIO, but

Martin L. schrieb:
> using the NimBLE-Arduino library.

https://github.com/platformio/platform-espressif32/issues/1225#issuecomment-3044662953

h2zero NimBLE-Arduino README.md states:
> Note for ESP-IDF users: This repo will not compile correctly in ESP-IDF.
> An ESP-IDF component version of this library can be found here.
>
> https://github.com/h2zero/esp-nimble-cpp