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[[Category: NexJ_Express]]
[[category: NexJ Express PhoneGap]]
*** For the blood pressure meter, pairing can be set but data transmission is unstable. The reason could be: The A&D medical device always forces one to use RFCOMM port/channel 1 for the connection; but the Android device will choose the next available channel.
=== Summary of Bluetooth communication test between Android and A&D BTP PBT Series devices===
* After the research efforts of many weeks, we have successfully built Bluetooth communication test programs: one is an Android native application; the other is based on PhoneGap (plugin on Android) framework.
** The two versions of the testing code, through Android Bluetooth APIs, make the Android devices work as Bluetooth server and perform SPP communication of Bluetooth.
** Android devices: The minimum version of Android is targeted at Android 2.2 and the test devices are HTC Desire (Android 2.3.3) and MOTOROLA XT885 (Android 4.04).
** Medical devices: A&D BTP PBT series which are SPP and SDP conformable. We use A&D UC-321PBT(Weight scale) and UA-767PBT (Blood Pressure Monitor).
* Important research findings for building the Bluetooth applications:
** Use the right Bluetooth service name and application UUID (00001101-0000-1000-8000-00805f9b34fb).
** Set the Android device to 'discoverable' state for the first medical measurement even through it should not be necessary for a paired device.
** About the issue of "Android Bluetooth server works only after rebooting the Android device". This is a tough issue which costs us weeks to address. Based on the searches on the Internet, we have concluded that the medical devices use the fixed RFCOMM port number - #1 to communicate with Bluetooth servers. But beginning with Android 2.0, Android Bluetooth API uses '''random ''' RFCOMM channel/port numbers for SPP SDP process and does not allow developers to set the port number manually any more. This conclusion is "confirmed" by the documentation in the A&D Blackberry code from NexJ, which states that port #1 must be used to build Bluetooth server socket. Eventually, we found the real season reason which causes the communication problem: when . When the Android application exits by clicking the "back" or "home" button, the application becomes inactive but its '''Bluetooth server thread ''' keeps receiving signals from medical devices. So newly started applications cannot receive data. Therefore, "A&D BTP PBT devices use fixed port# for SPPcommunication" could be right for the early products. But current market products of the A&D BTP series (UC-321PBT and UA-767PBT) are SDP conformable and are able to use any RFCOMM port number provided by a Bluetooth server.** The data transmission process needs to dealing deal with '''invalid data ''' generated by medical devices. In the tests, we have found out that the medical devices sometimes send out invalid measurement data and . An inappropriate process to for these data will cause exceptions and therefore interrupt the Bluetooth communication. As a result, leading to these invalid measurement records are accumulated within the medical device's storage (up to 40 records). In these casesThus, each time a new measurement is made, all the old invalid records will be sent to the Bluetooth server before the new one is sent, causing poor performance and even communication failure. The solution for this issue is that the Bluetooth server accepts these invalid data instead of giving exceptions to interrupt the communication process.** To make sure get right readings from UA-767PBT devices, one of the success way is to read the bytes from datainputstream one by one until appropriate length is reached.
