Im trying to read the RSSI values of a connected BLE device using btmgmt rust library, and always getting 127.

我正在尝试使用btmgmt rust库读取连接的BLE设备的RSSI值，但总是得到127。

    pub fn get_rssi(&self) -> Result<i8, Box<std::error::Error>> {
        let btmgmt = btmgmt::BTMgmt::new()?;
        let address = btmgmt::address::Address::from_string(
            self.addr.as_str(),
            btmgmt::address::AddressType::LeRandom,
        )
        .ok_or("invalid address")?;

        let ci = btmgmt.get_connection_info(u16::from(self.adapter_id), &address)?;

        Ok(ci.rssi)
    }

I know for sure that the device is connected, and had services resolved, here's bluetoothctl output:

我确信该设备已连接，并已解决服务问题，下面是BluToothctl输出：

Device DA:A4:58:46:AE:9F (random)
    Name: Device_name
    Alias: Device_name
    Paired: no
    Trusted: yes
    Blocked: no
    Connected: yes #<------------------------------- Connecter yey 🙂
    LegacyPairing: no
    UUID: Vendor specific           (********-****-****-****-************)
    UUID: Generic Access Profile    (00001800-0000-1000-8000-00805f9b34fb)
    UUID: Generic Attribute Profile (00001801-0000-1000-8000-00805f9b34fb)
    RSSI: -33 #<------------------------------------ We even have RSSI here.
    AdvertisingFlags:

I've tryied to call btmgmt using cli, yet it complains that the devices is not connected:

我尝试使用CLI呼叫btmgmt，但它抱怨设备未连接：

$ sudo btmgmt conn-info DA:A4:58:46:AE:9F                                  
Get Conn Info for DA:A4:58:46:AE:9F (BR/EDR) failed. status 0x02 (Not Connected)

Just for sanity check, I've compared to my connected Bose QC3's (Also BLE device) output:

只是为了检查，我比较了我连接的Bose QC3（也是BLE设备）的输出：

$ sudo btmgmt conn-info 4C:87:5D:0C:B5:FC                                 
Connection Information for 4C:87:5D:0C:B5:FC (BR/EDR)
    RSSI 0  TX power -3 maximum TX power 12

1. What am I missing?


2. Why btmgmt cant get connection info, while it seems everything is resolved as expected by the output of bluetoothctl?

Bluez - 5.53

Kernel - 5.15.0-83-generic

BlueZ-5.53内核-5.15.0-83-通用

After all @Emil was right, thanks!

毕竟@Emil是对的，谢谢！

If I failed to get conn-info at first because I called:

如果我一开始因为打电话而无法获得conn-info：

sudo btmgmt -t 2 conn-info DA:A4:58:46:AE:9F

But After reading this.

The -t 2 flag location is imported:

但在读完这篇文章后。导入-t 2标志位置：

$ sudo btmgmt conn-info -t 2 DA:A4:58:46:AE:9F
Connection Information for DA:A4:58:46:AE:9F (LE Random)
    RSSI -48    TX power 7  maximum TX power 7 <------------- Got result!