无法向 BLE 外设 (ZL-RC04A) 设备发送数据

Question

我正在尝试使用代码 sn-p 写入数据。

- (void)peripheral:(CBPeripheral *)peripheral1 didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error
{
    // Again, we loop through the array, just in case.
    for (CBCharacteristic *characteristic in service.characteristics) {

        // And check if it's the right one
        if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:TRANSFER_CHARACTERISTIC_UUID]]) {
            NSString *payloadMessage = @"3N";
            NSData *payload = [payloadMessage dataUsingEncoding:NSUTF8StringEncoding];
            [_discoveredPeripheral discoverDescriptorsForCharacteristic:characteristic];
            [_discoveredPeripheral writeValue:payload forCharacteristic:characteristic
                              type:CBCharacteristicWriteWithResponse];
            [_discoveredPeripheral setNotifyValue:YES forCharacteristic:characteristic];

        }
    }

}

但出现错误

 - (void)peripheral:(CBPeripheral *)peripheral didWriteValueForCharacteristic:(CBCharacteristic *)characteristic error:(nullable NSError *)error
{

}

作为： Error Domain=CBATTErrorDomain Code=3 "Writing is not permitted." UserInfo={NSLocalizedDescription=Writing is not permitted.}

虽然同样适用于 android。

Answer 1

如果您对特征使用了错误的写入类型（假设该特征毕竟是可写的），则会出现该错误。向特征写入数据有两种类型：

1. CBCharacteristicWriteWithResponse：在这种情况下，您将收到外设的确认数据包。您可以将其视为 TCP 数据包。

2. CBCharacteristicWriteWithoutResponse：这是一种“一劳永逸”的写作方式。您可以将其视为 UDP 数据包。

因此，请尝试使用CBCharacteristicWriteWithoutResponse 而不是CBCharacteristicWriteWithResponse。如果这不起作用，您可能必须检查您的特征是否是可写的。