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CC1350: Latency of Rx & Tx

Azor_Ahai
Prodigy 150 points
Part Number: CC1350


Hi, I am trying to measure the latency of CC1350 when sending a 1 kByte of userdata over Sub-1 Ghz Rx & Tx.

I have two CC1350 Launchpads and I am thinking of sending a few packets of data, put an interrupt when the first packet is sent from Tx so that a timer starts counting (in ms) and get an interrupt when the Rx received the last packet of data.

Questions:

1.) Is this the right way to find a latency?

2.) I am thinking of sending 4 packets of 260 bytes data each (preamble:4 bytes + syncword: 4 bytes + CRC:2 bytes + UserData: 250 bytes).

Is that okay and how do I set up these parameters in the code?

3.)How do I regulate the timer and interrupt to find out the time (in ms) between data being sent and data being fully received?

Thank you for any of your answers!!

Bojan

  • 0
    TI__Guru**** 317180 points
    - Exactly which latency do you want to find?
    - Are you intending to generate an interrupt from the LP in RX to stop the timer on the LP in TX?
    - Have you looked into if some of the signals here: dev.ti.com/.../signal-routing.html can be used and measure the latency usign a scope?
  • 0 in reply to TER
    TI__Prodigy 150 points
    1.) I would like to find the time needed for the packet to be delivered (from the point first packet is sent to the point where the transmission is over)
    2.)I was thinking to start a timer on Tx when the first packet is sent and stop the timer when the Rx received the last packet.

    What do you think is the best approach? Thank you!
  • 0 in reply to Azor_Ahai
    TI__Guru**** 317180 points
    This has been lost in my mail box. Have you looked into using time stamps for this?
  • 0 in reply to TER
    TI__Prodigy 150 points
    Hi,

    what do you mean by using time stamps?
    I did it the following way:

    I set up the Tx so that when the first package is being sent the LED toggles.
    I set up the Rx so that when the last package arrives the LED toggles.
    Connected them both to the oscilloscope and triggered and measured the time between the 2 LEDs.

    Is this the right way? I got a value of 19ms for the payload of 1kByte (500 kbps, 2 GFSK mode)

    Thank you for your answers !