Hi.
Using 51822 with BLE stack, I was faced with the problem of low transfer rates (5kb) on my android device (phone). It is very slow.
Can work 51822 with standart Bluetooth (not BLE)?
Hi.
Using 51822 with BLE stack, I was faced with the problem of low transfer rates (5kb) on my android device (phone). It is very slow.
Can work 51822 with standart Bluetooth (not BLE)?
Hello,
Unfortunately, the nRF51822 does only work with BLE. Your data transfer rate is a little low, which Android version do you have?
By theory, with BLE, you can have maximum 6 packets per connection interval and minimum 7.5ms connection interval. This results the maximum throughput of (1000/7.5) * 6 * max_payload_size. Currently the nRF51822 supports max_payload_size = 20 bytes. (MTU = 23 byte, 1 byte opcode, 2 byte handle).
So the maximum data throughput that the nRF51822 can achieve is in best case = (1000/7.5) * 6 * 20 = 16 kB/s.
However, usually you will not be able to achieve this speed due to limitations on the host. On iOS and Android usually you will have maximum 4 packet per connection interval. On Android devices you can get as low as 7.5ms connection interval. On iOS device, you can get something around 20 ms connection interval.
On the test here with a Samsung S4 running Android 4.2.2, we transferred 20kB in ~1850ms (~10.8 kB/s) from the nRF51822 to the phone.
Throughput on the other direction should be very similar.
How quick the host can support depends much on the available resources on the host stack, if it have to handle several slaves which also require high bandwidth, the throughput for each will be reduced (less packets per connection interval).
Same apply for PC, not all PC BLE stack and driver support 6 packets per connection interval and 7.5ms connection interval.
Also note that with Android 4.3 on S4, the minimum connection interval is 30 ms, leading to lower data rate.
Regards, Kristin
Hi Kristin, I am working on a sensor device using S110 and I am looking for the peer central device(e.g. smartphone, tablet or PC) to which S110 can send 6 packets at each connection interval.If you do not mind, could you tell me about the peer device you used for S110 thoughput measurement as mentioned "table 15 of section 7 Radio Notification on S110 nRF51822 SoftDevice Specification v1.3".
Hi Kristin, I am working on a sensor device using S110 and I am looking for the peer central device(e.g. smartphone, tablet or PC) to which S110 can send 6 packets at each connection interval.If you do not mind, could you tell me about the peer device you used for S110 thoughput measurement as mentioned "table 15 of section 7 Radio Notification on S110 nRF51822 SoftDevice Specification v1.3".