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MSPM0L1306: Noise on external clock input

ryota.endo
Intellectual 300 points
Part Number: MSPM0L1306
Other Parts Discussed in Thread: MSP430FR2476,

Tool/software:

I would like to know which of the external clock input pins, MSPM0L1306 or MSP430FR2476, is more resistant to noise.

The external clock is 40kHz,

MSPM0L1306: PA14/TIMG1.CCP0

MSP430FR2476: P1.6/TA1CLK

The pins for the external clock are set as above.

When comparing the MSPM0L1306 and MSP430FR2476, is there any reason or basis for saying that the MSPM0L1306 has higher noise resistance, for example, the MSPM0L1306 pins have lower input impedance and are less susceptible to noise, or the input capacitance is lower and therefore less susceptible to noise?

  • 0
    TI__Mastermind 24405 points

    Hi Ryota,

    What is the external clock used for? As the clock source for MCU, or only use MCU to detect the clock frequency.

    The input impedance / capacitance will give different capability for noise tolerance. The spec you can check with the data. In my understanding, higher impendence / capacitance could give a better performance on input volatge level checking.

    While for the clock source input, the things are become difference, it is edge detection rather than level detection.This will be related to the internal trigger circuit. So, it is hard to say which one is better.  From my perspective, I cannot guarantee which is better on this aspect.

    B.R.

    Sal

  • 0 in reply to Sal Ye
    Intellectual 300 points

    Used for timer counting.
    I created programs for the MSPM0L1306 and MSP430FR2476 that count an external clock and invert the output every 1 ms, and checked their operation, but when I looked at the operation of the MSP430FR2476, the value once became 0.97 ms (off by about 1 external clock clock).
    Since I checked the operation of both the MSPM0L1306 and MSP430FR2476 in the same test environment where noise is likely to be present, I asked whether it is possible that the MSPM0L1306 is resistant to noise while the MSP430FR2476 is susceptible to noise.
    Of course, it is possible that the MSP430FR2476 is malfunctioning, but it only happened once and is currently working without any problems, so I don't know what the cause is.
    I think that basically when the external clock is disturbed by noise or something, the input to the microcontroller changes, resulting in an incorrect count, but is it also possible that the microcontroller is malfunctioning?

  • 0 in reply to ryota.endo
    TI__Mastermind 24405 points

    Hi Ryota,

    It is hard to tell. you are using counting timer mode, so if there is a noise which input a valid edge, then it could makes the count incorrect, such as the counting time is smaller than the normal.

    We do not have some experimental data could prove the noise tolerance of the device. And, it is more like a system level spec. Usually, a small capacitor in the input pin could improve the performance.

    B.R.

    Sal