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MSP430F67791A: Optimization Inquiry: Tamper Detection Circuit for Custom Board Design

Nitheesh kumar R
Prodigy 100 points
Part Number: MSP430F67791A
Other Parts Discussed in Thread: TIDA-01377, , LDC0851

Hi,

We're currently designing a custom board with the MSP430F67791AIPEU microcontroller and have reviewed the schematic of the TIDA-01377 reference circuit for tamper detection. However, the circuit is overly complex[SIZE] for us. Our requirements are detecting enclosure tampering, recording time/date of events, and LED indication.

Could you please guide us on optimizing the circuit to minimize its size?

 
Regards,
Nitheesh.
  • 0
    TI__Mastermind 18270 points

    Hi Nitheesh,

    There are 2 main components to this circuit. The LDC0851 to detect a tamper event and the MSP430F67791A to handle the processing from the tamper event. The design uses inductive sensing in order to detect the tamper event but other ways to detect a tamper event are possible. The following E2E blog goes over some other options and the idea behind tamper protection.

    https://e2e.ti.com/blogs_/archives/b/smartgrid/posts/meter-anti-tampering-stopping-those-pesky-meter-tamperers

    Considering this design is only 2 ICs and minimal passive components, the only option to reduce the design size is adjusting the coils size themselves. or decrease the trace length between the LDC0851 and the MSP430F67791A.

    Regards,
    Luke 

  • 0 in reply to Luke Ledbetter
    Prodigy 100 points

    Hi,

    LDC0851 and MSP430F67791A is mandatory, that's fine. Other than that, JTAG and coils are mandatory, right? Similarly, I am asking which sections are mandatory in TIDA-01377 for achieving our requirements like detecting enclosure tampering, recording time/date of events, and LED indication.

    Could you please guide us on optimizing the circuit?

    Regards,

    Nitheesh
     

  • 0 in reply to Nitheesh kumar R
    TI__Mastermind 18270 points

    Hi Nitheesh,

    The MCU takes care of the recording of time/date and the LED indication. The LDC0851 will send a signal to the MCU based on a tamper event.

    The design doesn't have any extraneous components, I would say on physical design you could reduce the trace length between LDC0851 and MCU but the design itself would need to be maintained.

    Regards,
    Luke

  • 0 in reply to Luke Ledbetter
    Prodigy 100 points

    Hi,

    Thanks for your response.

    We use a specific module on our custom board. If I connect the output of the LDC0851 to the GPIO of our module, can I detect the enclosure case opening tamper event, or is there anything else that needs to be changed in the circuit

    Could you please provide the guidance on how to integrate the LDC0851 with our module[GPIO]?

    Regards,

    Nitheesh

  • 0 in reply to Nitheesh kumar R
    TI__Mastermind 18270 points

    Hi Nitheesh,

    In the MCU, the GPIO will be configured as an input and I suggest having an interrupt for when the GPIO changes states. In the interrupt service routine, you can then take a capture of the RTC values for a timestamp and do other processing as required in your application for a tamper event.

    The LDC0851 output signal is a digital signal and shouldn't be fast switching (considering a tamper event should not be a common occurrence), so you can do a direct trace from the LDC0851 to the MCU. I would also supply them on the same VCC rail so the digital signals are the same voltage levels.

    Regards,
    Luke

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