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RF430FRL152HEVM: EnergyTrace Power Measurement

Part Number: RF430FRL152HEVM
Other Parts Discussed in Thread: ENERGYTRACE, RF430FRL152H, MSP-FET

Dear Experts,

I am working on a project using RF430FRL152HEVM dev board. My goal is measure the chip energy consumption in LPM3 mode while running my program. For this I am using EnergyTrace technology, however, I was not able to have less than 0.11mA of current consumed, and less than 0.37mW of power overall, which is much too much according to the datasheet and estimated power consumption of LPM3 mode.

My question is, how exactly EnergyTrace is measuring the current? Do the other ICs on the board affect the EnergyTrace readings? For example, the RF430FRL152H chip is powered from the MSP-FET debugger, but the voltage there is stepped down via the TPS72215 chip, which also powers the phototransistor. I would also like to ask what exactly EnergyTrace measures, is it the power consumed by the microcontroller (and only the microcontroller) or is it the power consumed by the entire board?

Best regards,

Mateusz

  • Hello Mateusz,

    the LPM3 current consumption in the datasheet is specified for the standalone RF430FRL152H, without additional current at the IO pins. This can be achieved as stated in note (1) of chapter 5.5. in the datasheet. Inputs should be connected to 0V or VDDSW, to avoid floating. Outputs should not source or sink any current. If you are using a customized Firmware, then you should take care of these aspects.

    According to the datasheet, the LPM3 current is measured into the VDDB pin when it is supplied with 1.5V.

    I guess the RF430FRL152HEVM circuitry together with the standard firmware, does not provide a perfect setup to measure the LPM3 current. The RF430FRL152HEVM users guide is containing the hardware schematics in chapter 8. I would recommend to measure the supply current at JP3 of the battery terminal while switch S6 is switched to "Battery". LPM3 could be configured for the existing EVM firmware with help of the RF430FRL152HEVM PC GUI in tab Gen. Device Config. The Battery Switch should also closed. This way I was able to measure 20.6uA current consumption on my RF430FRL152HEVM. It is still not close to the expected 13uA, but maybe the light sensor or some other components on the EVM board are causing additional current consumption.

    Let me know if this could solve your problems or if you have additional questions.

    Best regards,

    Andreas.

  • Hello Mateusz,

    I missed the point that you want to use the Energy Tracing feature of the MSP430 FET. This technology is evaluating the pulse width of a DCDC converter inside the FET, which is generating the target board power supply. This measurement is reflecting the total current consumption of all circuitry on the RF430FRL152HEVM (including level shifters, etc.). If you are interested in the RF430FRL152H standalone current consumption, then you should measure it separately.

    Best regards,

    Andreas.

  • Dear Andreas,

    Thank you very much for such a detailed overview!

    I have though one more question, is it possible to evaluate somehow in details in which LPM mode RF430FRL152H chip actually is while debugging and stopping at breakpoint?

    In case of lowering the power output I tried also to terminate the unused ports, however in ULP advisor I constantly get the warning that Port A is uninitialized. Is there any recommended way to deal with unused pins in RF430FRL152H, I couldn't find any relevant example in the projects provided by TI, and the documentation is not so clear for me when I try to compare it with ULP Advisor messages.

    My goal is to closely match the energy of the chip to a specific program running at a relatively low frequency (the program is designed to collect temperature measurements every 1 minute). Therefore, I would like to use energy trace to accurately evaluate my code and the state the chip is in to optimize power consumption accordingly. From what I understand, with this board and chip it is not possible to track energy consumption so accurately. If this is not possible with EnergyTrace, is there any recommended way to do this?

    Sorry for such a lot of questions, but I havent found any consistent documentation or answer on TI forums on those topics, related to RF430FRL152H IC.

    Best regards,

    Mateusz

  • Mateusz,

    Yes, you can check the Status Register (SR) bits SCG1, SCG0, OSCOFF and CPUOFF (see Table 1-2). But is hard to debug further, as the CPU is off in LPM3.

    The recommended termination of unused pins can be found in chapter 1.7 of the RF430FRL15xH Reference Manual (https://www.ti.com/lit/pdf/slau506).

    Maybe you can calibrate the offset of the energy trace readings. Therefore you could disconnect the JTAG cable from the RF430FRL152HEVM, remove jumper SV7 and then reconnect the JTAG. By default the chip internal Battery Switch is turned off, and with the removed Jumper SV7 the device is entirely unpowered. The Energy Trace readings in this state should now reflect the remaining circuitry current consumption, which is the offset for the actual readings, when running your software.

    Alternatively you can sample the current consumption in Battery mode at the battery terminal with a suitable instrument.

    Best regards,

    Andreas.

  • Dear Andreas,

    Thank you for the detailed answer, this basically solved all of my issues! I was able to measure the power consumption with quite nice accuracy (results are close to the declared in the datasheet of RF430FRL152H) :)

    Thanks!