High transmission rate of sample data using ble_hrm and NRF51DK

[Manu]

Hi,

I am sampling 2 200Hz signal using ADC and transmitting data using heart rate and battery service of ble_hrm(instead of using simulated data).

But since the connection parameter cannot be lower than 7.5ms(makes it 133Hz), I am not able to reconstruct the signal on the android phone( need atleast 400 Hz).

I am able to reconstruct only 1 Hz signal, I am sampling at 1KHZ.

Is there a way to increase throughput using these same service?

Should I use a custom service where I can change the size of packet? If yes, I need help on how to start building one using NRF51DK

[Hung Bui]

1 Hz is very low, Manu. How did you send the data, via notification or write or read ?

You need to make sure you have low connection interval. And if the phone accepts that connection interval you request.

A sniffer trace would be very useful to reveal what happens in the air.

[Manu]

Its via notification, heart rate service sends heart rate value through notification. I am using battery level service to send the other analog data but its read type

[Hung Bui]

@Manu: Can you capture a sniffer trace ?

How did you queue the notification ? Have you tried to call sd_ble_gatts_hvx command as much as possible (until you receive BLE_ERROR_NO_TX_PACKETS ? Have you checked what was the actual connection interval ? (there is a chance that your connection parameters request was rejected )