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how to change CC2541 connection period ?

Hi,


When I tried different sets of connection parameters then I observed that it also changes connection period (3.68ms as in below snapshot) based on the connection interval that we set. If the connection interval is short then connection period is also short and similarly it shows the behavior for longer connection interval. Is it possible to keep the connection period shorter even after we configure longer connection interval ? Is there any link layer settings available in BLE stack.   

  • Hi,

    The snapshot is not view able in the browser. But generally the connection period consists of the following activities - wakeup, pre processing & packetization of data, RF Rx and Tx. , Post Processing and required event handling, powering down of different domains to prepare to sleep.

    Normally the wake up time, RF Rx and Tx time and Power down time are similar except if there are more packets to sent or receive.

    The pre and post processing time can vary depending upon the operations you do in the system. So with longer connection interval, the pre and post operations times can vary little bit, but not very significantly(unless you do a lot of processing of data).

    Regards,
    Arun
  • Hi Arun,

    Thanks for your reply.

    Sorry about the snapshot but it shows the connection period as 3.8ms. If I configure the connection parameters in a different way then it goes up to 2.9ms which is a huge difference from my product perspective.

    Hence it appears to me that increasing the connection interval also increases the BLE scan interval automatically at link later. I tried to set the following parameters to check if that can change the scan interval but it did not help me.

    TGAP_GEN_DISC_SCAN_INT
    TGAP_GEN_DISC_SCAN_WIND
    TGAP_LIM_DISC_SCAN_INT
    TGAP_LIM_DISC_SCAN_WIND
    TGAP_CONN_EST_INT_MIN
    TGAP_CONN_EST_INT_MAX
    TGAP_CONN_EST_MIN_CE_LEN
    TGAP_CONN_EST_MAX_CE_LEN

    Please let me know if you need further clarification.

    Regards,
    Vivek
  • Hi,

    Even while the application has not data to send, the Event period can be more than 2.5 ms. And at what value of connection interval do you see such changes? Are you doing any processing of data transfer during these connection events?

    Regards,
    Arun
  • Hi,

    If I set connection parameters as, min connection interval = 32, maximum connection interval = 48 and slave latency = 0 then connection period is around 3 ms.

    But if i change these parameters either by increasing the slave latency or connection intervals so as to get an effective connection interval of 2 secs then the connection period is around 3.7ms or even more.

    I am not sending any data, those are just empty connection PDUs.

    Regards,

    Vivek

  • Hi,

    Even if you are not sending any actual data, Empty connection PDUs will be sent. And because of such long connection interval, the device might process some pending task all at one go, but there should be not much difference in pre and post processing time like you have mentioned. We will have a look at this will get abck to you. I assume youa re using the simpleBLEperipheral example.

    Regards,

    Arun

  • Hi,

    To be honest, I am not sure what is it that is taking the extra time. It could be the processing time as you said or link layer scanning for more time. But it would be of great help to find out any sort of settings that can reduce the interval.

    I am using Keyfob with peripheral configuration.

    Regards,
    Vivek