Re: BLE4.0 VSP transmission speed
Re: BLE4.0 VSP transmission speed
- Subject: Re: BLE4.0 VSP transmission speed
- From: William Henderson <email@hidden>
- Date: Tue, 06 Aug 2013 22:55:52 -0700
That's right, you'll definitely want a checksum of some kind. IME, writes do fail occasionally (both async and sync but async somewhat more often), especially with interference. That said, it's still much faster (even after starting a transmission all over) to do your writes async if you've got to move a lot of data. I've see 5+kbs async vs less than .5kb/s sync.
On Tuesday, August 6, 2013 at 10:52 PM, Etan Kissling wrote:
William,
asynchronous writes are not reliable, meaning that arbitrary packets may be dropped at any time
by either sender or receiver stack. It may work better with two iOS devices, as they rarely drop
packets on their side - but wouldn't bet too much on stuff that's not pointed out in the documentation.
So, at least add some kind of checksum at the end if you are using multiple iOS devices to ensure
that no packet has been lost.
Etan
wrote:
Tips from the CoreBluetooth side:
- write asynchronously (CBCharacteristicWriteWithoutResponse)
- make sure your peripheral supports asynchronous writes
- give your central manager object its own dispatch queue
CBPeripherals are limited to a 20 byte MTU, and I have no trouble writing over 15kb that way (takes a few seconds).
On Monday, August 5, 2013 at 6:21 PM, Chen, Baimen wrote:
I develop an app with BLE4.0 to control our device. We use VSP for data transmission, but I find VSP can't transfer much data, such as more than 256 bytes, always lost packet and updatedCharacteristic method be invoked frequently, some time only receive one
byte.
The lost packet may be caused by our BLE4.0 supplier.Their MAX RF packet is only 20 bytes,The UART and VSP buffer are both 256 bytes. Who can give me some suggestion? If you want transfer much data, such as much than 1000 byte, how do you do that? Thanks!
Yours sincerely,
Kevin Chen
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