Bluetooth

Field Guide 12 · 24 min read

Discover BLE devices, inspect and save advertising data, measure signal strength, and browse GATT services.

Before you start

Before you connect

BLE addresses, names, manufacturer data, services, and values can identify people or equipment. Connect or write only with authorization.

Leave Wi-Fi before opening Bluetooth.

Scan Devices

Scan Devices discovers nearby Bluetooth Low Energy advertisements and displays their available identity and advertising data.

Menu pathMain Menu → Bluetooth → Scan Devices

1. Wait while the M1 finds nearby devices.
2. Browse by name or address; unnamed entries are numbered for the session.
3. Press Center on Details.
4. Use Left and Right through identity, RSSI, flags, UUIDs, manufacturer data, and parsed fields.
5. Press Center on Save to name a live record under ble/.
6. Press Back to the device list, then Back to leave.

Advertisement snapshot

A saved record is not a pairing record and does not prove the device is connectable.

Signal Meter

Signal Meter tracks the selected device’s received signal strength to help with relative proximity checks.

Menu pathMain Menu → Bluetooth → Signal Meter

1. Select the target.
2. Wait while the M1 measures the signal.
3. Read averaged RSSI and signal category.
4. Move slowly with consistent orientation.
5. On Signal lost, move closer or confirm advertising continues.
6. Press Back to stop.

RSSI shows relative signal strength, not exact distance. Walls, people, orientation, interference, interval, and transmit power affect it.

GATT Explorer

GATT Explorer connects to a BLE device and browses its services, characteristics, and supported actions.

Menu pathMain Menu → Bluetooth → GATT Explorer

1. Select a device and press Center on Connect.
2. Wait for connection and service discovery.
3. Select a service, then a characteristic.
4. Choose an action supported by the characteristic.
5. Press Back one level at a time to return or disconnect.

Action	Instructions
Details	Review UUID, handle, properties, and descriptors.
Read	Request current length and hexadecimal bytes.
Write	Enter even-length hex up to 64 bytes and send with response.
Write No Rsp	Send even-length hex without application confirmation.
Notify	Subscribe via CCCD and watch notification values; Back stops.
Indicate	Subscribe to acknowledged indications when supported; Back stops.

Writes change devices

Do not write unless the exact characteristic, value, and expected effect are documented.

Saved

Saved opens previously stored BLE advertisement snapshots without making a live connection.

Menu pathMain Menu → Bluetooth → Saved

1. Select a .ble file under ble/.
2. Press Center to open it.
3. Use Left and Right through stored details.
4. Compare with a new scan when current state matters.
5. Press Back to close.

Opening a saved record does not connect to the device or provide live GATT controls.

Troubleshooting

Problem	What to do
No devices	Wait, move closer, and confirm advertising.
Radio busy	Leave Wi-Fi.
Connect failed	Confirm connectable, nearby, and not connected elsewhere.
Read failed	Security or pairing may be required.
Not subscribable	No usable CCCD or Notify/Indicate property.
Write rejected	Verify properties, security, byte format, and authorization.
Saved empty	Check .ble files under ble/ and card mount.

Visual guide

BluetoothUse Up and Down to move the highlight. Center opens the selected item.

Device discovery

Scan→Select device→View details→Save snapshot

GATT Explorer

Device→Service→Characteristic→Read, write, or subscribe

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Need help? Email support@monstatek.com and include the firmware version and screen name.