topic Re: External interrupt frequency in S32K

External interrupt frequency

zhouqicheng — Tue, 05 Sep 2023 09:15:00 GMT

Hello, I used an external interrupt falling edge trigger to measure the number of square waves. The square wave frequency is 125khz and 8us per cycle. I found that the counting of square waves tends to be smaller when it exceeds 1000. What is the interrupt counting frequency of S32K144 pin? How to ensure that pin interruption triggers are not lost,

Re: External interrupt frequency

Senlent — Wed, 06 Sep 2023 02:03:47 GMT

Hi@zhouqicheng

1.What is the interrupt counting frequency of S32K144 pin?

There is no such verification data, this can vary significantly on different clock configurations

2.You can control a GPIO port, set the port to output a fixed frequency and a specified number, and then connect the port to the input port.

3.For tasks such as measuring pulses, I generally recommend that users use the Input capture feature of FTM module.

Re: External interrupt frequency

zhouqicheng — Wed, 06 Sep 2023 02:45:33 GMT

Hello, how to count the number of PWM using the ftm input capture function? Only measuring frequency and cycle cases are available. Are there any relevant cases?

Re: External interrupt frequency

Senlent — Wed, 06 Sep 2023 02:49:49 GMT

Hi@zhouqicheng

try this demo, using FTM module to calculate PWM frequency.

https://community.nxp.com/t5/S32K-Knowledge-Base/S32K1-Calculate-the-motor-speed-based-on-the-FTM/ta-p/1515933

Re: External interrupt frequency

zhouqicheng — Thu, 07 Sep 2023 01:07:51 GMT

Hello, according to the above document configuration, it has been found that once the square wave is measured, it enters this interrupt and cannot operate normally. What is the problem

Re: External interrupt frequency

Senlent — Thu, 07 Sep 2023 01:19:41 GMT

Hi@zhouqicheng

please try the demo from the linker I provided earlier, maybe you missed something when you configuring you project.