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CCS/LAUNCHXL-CC1352R1: Using EnergyTrace with external target

Martin Boyd
Intellectual 810 points
Part Number: LAUNCHXL-CC1352R1
Other Parts Discussed in Thread: CC2652R, ENERGYTRACE

Tool/software: Code Composer Studio

I have a custom PCB using a CC2652R connected to a LAUNCHXL-CC1352R1 as an external target. The code is based on Simple_Peripheral.

EnergyTrace works fine using the onboard CC1352 and I get what looks like a correct current waveform showing spikes at the the BLE advertising intervals. i.e. I get something like this:

However if I try to use the external target with either an external power supply or the XDS supply I just get white noise, i.e:

I also noticed that if I restart the LAUNCHXL the magnitude of the noise changes drastically, in the capture below it is showing 4A which isn't possible.

This is how I have it connected:

What am I doing wrong?

  • 0
    TI__Genius 11810 points
    Hi Martin,

    To use the on-board EnergyTrace (ET) functionality the power selector jumper must be in the "XDS Power" position. In the "External Power" position, the current sensing resistor is floating and you will see "white noise". Every time a LaunchPad is powered up the ET circuitry is being calibrated and if the power selector jumper is in wrong position, the calibration will fail and ET will show wrong results.

    If you want to use ET on external target you should use the XDS power supply to power the board. You can supply current through the 10-pin JTAG cable, or from the 3V3 pin on the jumper block header on the XDS side of the LaunchPad (between RXD and 5V, on the XDS side).

    Another option, which will give better results, is to use an external power supply, but be aware that ET is limited to max. ~110 mA and does only support 3.3V. Then the external supply must be fed into the center pin of the power selector header and the LaunchPad must be power cycled for correct calibration. The target board must be supplied as described above. This method does also work for debugging the on board device.

    -Simon
  • 0 in reply to Simon J
    Intellectual 810 points

    I'm still not having any luck. If I run simple peripheral on the launchpad I get the waveform below, it looks correct although the average current of around 1mA seems high?

    If I then run our software on the launchpad I get the following, which looks good but with an even higher average current:

    Then I connect our board via JTAG and remove all the jumpers from P4 and leave the power set to XDS110 power and I get this:

  • 0 in reply to Martin Boyd
    TI__Genius 11810 points
    Hi Martin,

    Be aware that EnergyTrace on the current version of the CC13x2/CC26x2 LPs have some noise issues which will be fixed in the upcoming versions, therefore your results will not be very accurate. To get better results on the version you have, you should remove all of the XDS jumper block headers except the 3V3 jumper which powers the target, or you can use external power as described above.

    -Simon
  • 0 in reply to Simon J
    Intellectual 810 points

    Still no good, I tried using an external 3.3V supply to the centre pin and it didn't help. If I remove my board from the jtag connector it doesn't seem to make much of a difference to the measured current.

  • 0 in reply to Martin Boyd
    TI__Genius 11810 points
    Unfortunately, this is as good as it gets on this version of the LaunchPad. Consider EnergyTrace HDR Add-on probe: www.ti.com/.../TMDSEMU110-ETH together with www.ti.com/.../TMDSEMU110-U if you require better resolution.

    -SImon
  • 0 in reply to Simon J
    Intellectual 810 points

    thanks, I will try that.