MSPM0L1228-Q1: MSPM0L1228-Q1

Hi Haibo,

Could you explain how you are testing the impedance? A diagram showing the pin and your probes would be helpful. The Hi-Z leakage current for various pins is 50-300nA, so I would expect higher impedance than 1.3M ohm.

Hello Dylan

I cannot attach the diagram today. The backend is connected to the TXD pin of TLIN10283, which has 350k pull-up res.
When the output is high level , the measurement is only 2.6V.
So, by calculating, a pull-down resistance of 1.3M ohms is obtained.

Is anything else connected to the bus? What is the high voltage output of the TLIN when the MSP is not connected? What is the supply voltage to the MSP? I see your point with the voltage division math but I still do not think the Hi-Z resistance of the pin should be this low.

Hello Dylan

There's nothing else connected， high voltage output of the TLIN when the MSP is not connected is 3V3.

Now I need to add an external resistor, such as 10k, to ensure an output of around 3.28V.

When you are testing this, can you check your IOMUX settings for the pin and paste here?