topic S32K144 in S32K

S32K144

LzdOo — Mon, 14 Jul 2025 00:24:16 GMT

I use FLEXIO as the Master for I2C, and I call the SDK library functions I2C_MasterSendData and I2C_MasterReceiveData to read the registers. I wonder why the SDA and SCL captured by the oscilloscope are not normal? What causes SCL to be not a square wave but a triangular wave?

Re: S32K144

VaneB — Tue, 15 Jul 2025 16:00:03 GMT

Hi @LzdOo

Does the flexio_i2c_s32k144 example work without modifications?

Also, for I2C communication, pull-up resistors are required on both the SDA (Serial Data) and SCL (Serial Clock) lines to ensure proper functionality. These resistors are typically in the range of 2kΩ to 10kΩ, depending on the bus speed and capacitance. Have you connected them?

BR, VaneB

Re: S32K144

LzdOo — Tue, 15 Jul 2025 00:11:38 GMT

Hi, VaneB

Could you please tell me how I can modify my code?

(Both my SDA and SCL have 10KΩ pull-up resistors connected to them.)

Re: S32K144

LzdOo — Tue, 15 Jul 2025 07:41:32 GMT

Hi, VaneB

Slave address is 0x18, the address of the register to be read is 0x0F.

Based on the waveform, it seems that the code only executed the part for sending the SUB address, but did not execute I2C_MasterReceiveData. What could be the reason for this?

(The I2C timing sequence is as shown in the following figure.)

Re: S32K144

VaneB — Tue, 15 Jul 2025 16:08:12 GMT

Hi @LzdOo

If possible, could you please share your project files or code? That way, I can take a closer look at the implementation and configurations to better understand and visualize the situation.

Re: S32K144

LzdOo — Tue, 15 Jul 2025 23:42:02 GMT

Hi, VaneB

Sorry, my code is encrypted. Please explain based on your experience the possible reasons for the aforementioned phenomenon.

Re: S32K144

VaneB — Fri, 18 Jul 2025 22:36:10 GMT

Hi @LzdOo

You could try swapping out the 10kΩ resistors on the SCL line for ones with a lower value. Take a look at the waveform to see if there is any noticeable difference.