Re: Real time data transmit by BLE (iOS7)
Re: Real time data transmit by BLE (iOS7)
- Subject: Re: Real time data transmit by BLE (iOS7)
- From: John Earl <email@hidden>
- Date: Thu, 24 Oct 2013 08:08:00 +0100
What's the connection interval? The default connection interval is 30ms. By choosing the right connection parameters when sending a connection parameter update request we have been able to get this down to 18.75ms, but that is the best you can do. BLE is a low energy protocol and on iOS devices shares the antenna with, eg, WiFi. Accordingly it rejects overly short connection params.
To get the lower CI you must configure the nrf51822 to send a connection parameter update request some time after the connection is established. It typically takes 10-20 seconds to establish the new parameters. See the Apple Bluetooth Design Guidelines for the constraints on these parameters.
Should note that there is no obstacle to sending multiple values to the same characteristic in the same connection interval. So if you can relax your real time constraint a little you can certainly get the desired packet throughput, as 2 packets every 3s, for instance, without needing a 10s setup time to change the CI.
Best regards
John
On Thursday, October 24, 2013, hayatoliu wrote:
Dear All,
I'd like to use CBPeriperal to send data from iOS6.1.3 to BLE device
for "real time" data transmission. But I found that when I send 20
bytes (calling write value without response function) by iOS per
15ms, BLE device will receive the data per 30ms. I want the "recieve
rate" reaches 10ms, not 30ms. Is there any solution about real time
data transmission？Is the "receive rate" controlled by iOS ?
PS. I also use iOS7.0.3 , but I found that I can only use "write
value with response function", the "receive rate" will be 60ms! But
when I use "write value without response function", BLE device will
get nothing...
I use Nordic nrf51822 as BLE device to development.
Hayato
--
Hayato Liu
Unigrand LTD
7F., No.108-2, Minquan Rd., Xindian Dist.,
New Taipei City 231, Taiwan
TEL: +886-2-22180069
FAX: +886-2-22180078
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