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This function will retrieve a characteristic from the device.
To list all the known characteristics, keep calling this function with incrementing index until it returns -4 (_BT_ERR_NOT_FOUND).
Input:
dev : STRING
The address of the device to get the data from.
idx : INT
The index of the characteristic to read.
service : INT
The service to read the characteristics of.
Output:
char : INT
The ID of the characteristic.
flags : DINT
A bit field with the flags for this characteristic.
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Bit
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Hex
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Name
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Description
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2
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02
|
Read
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The characteristic can be read, see btleReadVal.
|
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3
|
04
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Write no response
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The characteristic can be written without waiting for response, which allows for higher throughput. See btleWriteVal.
|
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4
|
08
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Write
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The characteristic can be written and waits for the response. See btleWriteVal.
|
|
5
|
10
|
Notify
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The characteristic supports notifications, which can trigger events when the value changes. See btleNotifyStart.
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UUID : STRING
The UUID of this characteristic.
Returns: INT
1
|
-
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_BT_OK
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|
Success.
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0
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-
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_BT_ERR_NOT_SUPPORTED
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|
The API is not supported.
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-1
|
-
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_BT_ERR_NOT_OPEN
|
|
The adapter is not powered(see btPower).
|
-4
|
-
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_BT_ERR_NOT_FOUND
|
|
The device or characteristic could not be found.
|
-8
|
-
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_BT_ERR_INVAL
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This device does not have any characteristics.
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Declaration:
FUNCTION btleCharGet : INT;
VAR_INPUT
dev : STRING;
idx : INT;
service : INT;
char : ACCESS INT;
flags : ACCESS DINT;
UUID : ACCESS STRING;
END_VAR;
Example:
...
FUNCTION getServices
VAR_INPUT
dev : STRING;
END_VAR;
VAR
rc : INT;
rc2 : INT;
service : INT;
ch : INT;
primary : BOOL;
UUID : STRING;
i : INT;
c : INT;
flags : DINT;
END_VAR;
DebugMsg(message:="Get services for "+dev);
i := 1;
REPEAT
rc := btleServiceGet(dev:=dev, idx:=i, service:=service, primary:=primary, UUID:=UUID);
DebugFmt(message:=" btleServiceGet "+dev+": \1", v1:=rc);
IF rc = _BT_OK THEN
DebugFmt(message:=" Service: \1, primary: \2, UUID: "+UUID, v1:=service, v2:=INT(primary));
c := 1;
REPEAT
rc2 := btleCharGet(dev:=dev, idx:=c, service:=service, char:=ch, UUID:=UUID, flags := flags);
DebugFmt(message:=" btleCharGet "+dev+": \1", v1:=rc2);
IF rc2 = _BT_OK THEN
DebugFmt(message:=" Service: \1, Char: \2, flags: \4, UUID: "+UUID, v1:=service, v2:=ch, v4:=flags);
END_IF;
c := c + 1;
UNTIL rc2 <> _BT_OK END_REPEAT;
END_IF;
i := i + 1;
UNTIL rc <> _BT_OK END_REPEAT;
END_FUNCTION;
...
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