Connection Interval- NRF_ERROR_INVALID_PARAM

[Lakshmi_K]

Dear Sir,

We have 4 Nordic devices connected to 1 central. At every 195 to 182 seconds 1 packet is sent from device. 

I tried changing the following parameters just to understand criteria and got the error NRF_ERROR_INVALID_PARAM from sd_ble_gap_ppcp_set().

1. MIN_CONN_INTERVAL 500
2. MAX_CONN_INTERVAL 1000
3. SLAVE_LATENCY 199
4. CONN_SUP_TIMEOUT (400*1000)

From this post  connection interval error 

found out Supervision_Timeout  >  { (1 + Conn_Latency) * Conn_Interval_Max * 2} , where Conn_Interval_Max is given in milliseconds.

{(1+199) *1000 *2} = (400*1000). 

Can you help us in getting the desired connection intervals?

Regards,

Lakshmi

[Karl Ylvisaker]

Hello Lakshmi,

1. MIN_CONN_INTERVAL 500
2. MAX_CONN_INTERVAL 1000
3. SLAVE_LATENCY 199
4. CONN_SUP_TIMEOUT (400*1000)

From this post  connection interval error 

found out Supervision_Timeout  >  { (1 + Conn_Latency) * Conn_Interval_Max * 2} , where Conn_Interval_Max is given in milliseconds.

Both MIN_CONN_INTERVAL and MAX_CONN_INTERVAL are given as units of 1.25 ms, and so your max interval in this case is 1250 ms, which means that your CONN_SUP_TIMEOUT would need to be at least 500,000 ms to fulfil the inequality in the formula posted.

However, there is a hard limit on the maximum connection supervision timeout in the BLE specification which is 32 seconds, and so it is not feasible to use a slave latency of 200, please see this post for more information about this.

Best regards,
Karl

[Lakshmi_K]

Ok, we are using BLE-5 coded phy, 32 second limitation is applicable here also?

[Karl Ylvisaker]

Hello,

Yes, the 32 second limitation is regardless of which PHY you are using.

Best regards,
Karl