KL05 input port not working properly

[xiaotony]

Hi Guys

Recently, we encountered an issue the input ports fail to read the level correctly. after power off and on, it can back to normal, but the problem may recur after a few days

We are using MKL05Z32VLF4, and the problematic IO ports are PTA6 and PTB6, both configured as inputs with external pull-up resistors and designed to trigger respective functions on low-level signals.

when the issue appears, the low-level signals on these two pins are normal, and the other input pins, including uart & i2c communication and other functions, are all functioning properly. it confirmed the program is running normally; but not of these two input ports.

This issue has appeared on many of our devices, and it's strange that it's always appeared on these two IO ports. but not found on other PORTA and PORTB  input pins. Are there any special characteristics of these two IO ports? Any suggestion and solutions for this issue?

[_Leo_]

Hi,

Thank you so much for your interest in our products and for using our community.

There is no errata or other issue reported with the pins you mention.

However, consulting HW considerations of KLQRUG, general purpose inputs, such as low speed inputs, timer inputs, and signals from offboard should have low pass filters to prevent data corruption due to crosstalk or transients. The filter capacitor should be placed close to the MCU pin, while the resistor can be placed closer to the source (for more details please refer to 2.1.3.4.2 General purpose I/O section).

Hope it helps you. 

Have a nice day!