Scratch micro:bit extension与Scratch Link通信的细节

分析

在Scratch中选择microbit extension，前端发送发现硬件消息:

{"jsonrpc":"2.0","method":"discover","params":{"filters":[{"services":[61445]}]},"id":0}

Scratch Link不断回复:

{"params":{"name":"BBC micro:bit [gazat]","rssi":-32,"peripheralId":"89FC6234-54E4-4E68-8EE0-C947ECF9A292"},"method":"didDiscoverPeripheral","jsonrpc":"2.0"}

点击连接,前端发送消息:

{"jsonrpc":"2.0","method":"connect","params":{"peripheralId":"89FC6234-54E4-4E68-8EE0-C947ECF9A292"},"id":1}

Scratch Link回复:

{"id":1,"result":null,"jsonrpc":"2.0"}

前端发送消息：

{"jsonrpc":"2.0","method":"read","params":{"serviceId":61445,"characteristicId":"5261da01-fa7e-42ab-850b-7c80220097cc","startNotifications":true},"id":2}

之后Scratch Link回复

{"id":2,"result":{"encoding":"base64","message":""},"jsonrpc":"2.0"}

{"params":{"encoding":"base64","message":""},"method":"characteristicDidChange","jsonrpc":"2.0"}

{"params":{"encoding":"base64","message":"\/8oCygAAAAAAAAAAAAAAAAAAAAA="},"method":"characteristicDidChange","jsonrpc":"2.0"}

...

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参考

• 分析scratch3.0与micro:bit的通信