title: BLE gatttool cannot connect even though device is discoverable with hcitool lescan
body: <p>I'm running RPi with a USB Bluetooth dongle. When I use hcitool, I can discover the SmartTag device. But when I use gatttool, I cannot connect. It says "Host is down (112)". Here are my commands:</p>
  
  <pre><code>$ sudo hcitool lescan
  LE Scan ...
  BC:6A:29:AB:DE:2B (unknown)
  BC:6A:29:AB:DE:2B SensorTag
  </code></pre>
  
  <p>Checking for bluetooth adapters on my RPi I get:</p>
  
  <pre><code>$ hcitool dev
  Devices:
          hci0    5C:F3:70:60:E6:1B
  </code></pre>
  
  <p>Then, when I use the gatttool like this, I get:</p>
  
  <pre><code>$ sudo gatttool -i hci0 -b BC:6A:29:AB:DE:2B -I
  [   ][BC:6A:29:AB:DE:2B][LE]&gt;
  </code></pre>
  
  <p>When I type connect, I get this:</p>
  
  <pre><code>[   ][BC:6A:29:AB:DE:2B][LE]&gt; connect
  Connecting... connect error: Host is down (112)
  [   ][BC:6A:29:AB:DE:2B][LE]&gt;
  </code></pre>
  
  <p>I found some info on the web that said "Host is down" means that the bluetooth sensor is not in discoverable mode. But this is not correct as far as the SmartTag is concerned since I press the one button (side button) on the sensor that TI says to push to make it discoverable. And that same one is used by the hcitool lescan to find the device. There's also an android app that runs off a phone and it scans, connects, and reads the SmartTag sensor just fine when that same button is pressed.</p>
  
  <p>Does anyone know what the problem might be?
  Thanks in advance</p>