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MSP-EXP432P401R: battery operation testing

Laszlo Garab
Intellectual 965 points

Part Number: MSP-EXP432P401R

Hello,

I would like to test battery operation with LaunchPad. So, I disconnect 3V and 5V from the power rail, but how to interface SWD and USART if the battery voltage is varying from 3.7V to 3.0V.

Regards,

Laszlo

  • 0
    TI__Intellectual 2650 points

    Hi Lazlo,

    The positive-going input threshold voltage specification can be found in Table 5-23. Digital Inputs (Applies to Both Normal and High-Drive I/Os in the datasheet. At VCC = 3V, the max voltage required to detect a high would be 2.25V while the minimum would be 1.35V. As long as you meet the worst-case of 2.25V, you should be able to interface with the SWD and UART.

    For more explanation regarding this range, please refer to this report Understanding Schmitt Triggers.

    Here is also a thread that addresses similar content.

    Thanks,

    Urica Wang

  • 0 in reply to Urica Wang
    Intellectual 965 points

    Hi Urica,

    the problem is that LaunchPad XDS-110 SWD and UART runs at 3.3V and the tested microcontroller supplied from 3.7V to 3.0 depending on the charge of the battery. It means that neither high or low level converter does not fit for the application; because at the beginning low  conversion, at the end high conversion would be needed.

    As I think over the problem digital isolation could be a solution but needs further investigation.

    Regards,

    LAszlo