CC2642R: 3.3V EnergyTrace with 1.8V I/O

Hello Victor,

Please find this information inside the CC26X2 LaunchPad User Guide:

To use EnergyTrace the Power Jumper must be in the XDS110 Power position and the 3V3 jumper on the XDS header must be mounted to provide current to the target. The other jumpers on the XDS header are optional. EnergyTrace does only support 3.3 V supply voltage.

In regards to debugging and programming external devices:

With all the jumper block jumpers removed, the XDS110 Out header will work as debug output for the XDS110, and the Target In header will work as debug connector for the CC26x2R. The XDS110 output is level shifted and support target voltages between 1.8 V and 3.6 V. If the target board is powered externally, the Power Jumper must be moved to the external power position to set the correct level on the level shifters. The LaunchPad can also power the external board with 3.3 V, then the Power Jumper must be in the XDS110 Power position.

The CC26x2R is by default powered from the LaunchPad's 3.3 V LDO. It is possible to run the device off different supply voltages by disconnecting the 3.3 V jumper and connecting a power supply between 1.8 V and 3.6 V to any of the pins marked 3V3. In this case the Power Jumper must be placed in the Extern Pwr position to connect the external supply to the XDS110 level shifters. Note that even though the supply voltage range of the CC26x2R is up to 3.8 V, the maximum voltage in this case is limited by the level shifters at 3.6 V. When measuring current consumption, ensure that the serial (SPI) flash memory is placed into low power mode. Support for placing the serial flash into low power mode is provided in the LaunchPad board file included with the SimpleLink CC26x2R SDK.

Thus EnergyTrace can only support a 3.3 V supply voltage whereas the XDS110 level shifters would need to use the External Power reference to operate JTAG at 1.8 V.  Thus it is not possible to use EnergyTrace and a 1.8 V target supply simultaneously.  I recommend that you either use EnergyTrace at 3.3V supply to confirm low power operation or power the device externally and use a precision multimeter or power analyzer to further evaluate the board's power consumption.  You can also refer to SWRA478.  Note that the TMDSEMU110-ETH tools supports dynamic range capabilities, functionality which is not offered with the on-board XDS110.

Regards,
Ryan

Hello Ryan,

Thank you for your answer.

Does it mean plugging the TMDSEMU110-ETH in our XDS110 would allow us to supply and EnergyTrace at 3.3V while debugging at 1.8V with the XDS110 ?

Reviewing your original post I realize that you meant you already have a TMDSEMU110-U, is this correct?  I only meant to advertise the HDR tool's greater current range and accuracy, however the standalone XDS110 should be capable of selecting a voltage level from the Target Configuration (.ccxml) editor.  The EnergyTrace voltage set inside CCS's Window → Preferences → Code Composer Studio → Advanced Tools → EnergyTrace Technology is used to accurately interpret the values measured by the XDS110. The EnergyTrace tool requires that the XDS110 supplies the target's voltage for accurate measurements. You will need to disconnect JTAG to evaluate the system's 3.3 V level, or modify the board so that the XDS110 powers the CC2642R independently with 1.8 V.  Here are links to other resources:

https://dev.ti.com/tirex/explore/node?a=&node=A__ALFqIj4dX6S.TZRERoSphA__xdsdebugprobes__FUz-xrs__LATEST 
https://dev.ti.com/tirex/explore/node?a=&node=A__AA-JQ42-.QwOXoceOKh06A__xdsdebugprobes__FUz-xrs__LATEST 

Have you submitted your custom hardware design to SIMPLELINK-2-4GHZ-DESIGN-REVIEWS?  I will assign a HW expert to this thread for further review.

Regards,
Ryan 

Yes I already have a TMDSEMU110-U.

So as I understand I won't be able to use ET+ or ET++ then because it needs to use JTAG at the same time ?

The only solution I see would be to have level shifters on our board.

I haven't submitted the hardware design to review but I don't want to, thank you.

Regards, 

Victor

You are correct, ET+/ET++ requires JTAG to read the CPU/peripheral/system states.  You may still be able to do this so long as the XDS110 is not supplying power to the custom board, in which case any current measurements would not be valid.  I am not aware of any tests or validation which have been performed at TI for this use case.  You could experiment with on a LaunchPad before attempting to evaluate the custom board.

Regards,
Ryan