Bluetooth Low Energy
Designing GATT Services for a Custom BLE Product
A GATT interface is a contract between device firmware and its clients.
A GATT interface is a contract between device firmware and its clients. Document the data and permissions as carefully as an external API.
Model the product functions
Separate measurement, configuration and diagnostic functions into a clear service design. Use appropriate standard definitions where applicable and unique identifiers for custom functions. Specify characteristic formats, units and valid ranges so clients do not infer meaning from examples.
Define access and change behaviour
Choose read, write and update behaviour deliberately. Apply the required authentication and authorisation to configuration operations. State whether a write is immediately applied, requires validation or takes effect after restart, and expose meaningful error feedback.
Test client compatibility
Test older app versions, reconnects and firmware upgrades. Keep an interface version and migration policy for changed formats. Verify subscriptions, fragmented transfers where relevant and interrupted writes so a partially delivered configuration cannot be mistaken for a complete update.
FAQ
Can I change a characteristic format later?
Yes, with explicit versioning and compatibility handling; silently reinterpreting existing bytes can break clients.
Technical References
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