topic Re: S32K312 - How can I set I2C baud rate? in S32K

S32K312 - How can I set I2C baud rate?

ssean — Wed, 27 Dec 2023 08:16:02 GMT

Hello.

How can I set I2C baud rate for S32K312 MCU ?

Source clock from AIPS_SLOW, 30 MHz.

I want to set baud rate to 400 Kbps.

How can I set this config page ?

Best Regards,

SEAN SUNG

Re: S32K312 - How can I set I2C baud rate?

Robin_Shen — Thu, 28 Dec 2023 08:35:06 GMT

Please refer to the Table 424. Timing Parameters of S32K3XXRM. Modify the value of I2c Clock High Period(CLKHI) and I2c Clock Low Period(CLKLO). The I2c Baud Rate will be automatically calculated based on your input value and will be displayed there. But the value you configured now is too small, causing it to exceed the Baud Rate upper limit of LPI2C_FAST_MODE (so it is displayed in red). Please also note: Table 426. LPI2C Timing Parameter Restrictions

Best Regards,
Robin
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Re: S32K312 - How can I set I2C baud rate?

ssean — Fri, 29 Dec 2023 06:58:00 GMT

Dear Robin.

Thank you for reply.

I set CLKHI=31, CLKLO=42, FILTSCL=1, PRESCALE=2 (DIV4)

My calculated baud rate is 100000 (100K).

But S32DS auto calculated baud rate is 200000(200K).

What is my miss?

Could you check my project(attached), please?

And.. HAPPY NEW YEAR!

Best Regards,

SEAN SUNG

Re: S32K312 - How can I set I2C baud rate?

Robin_Shen — Fri, 29 Dec 2023 09:01:57 GMT

Hi SEAN SUNG,

I think it should be 100K. Maybe the S32 Configuration Tool calculated it wrong. It is recommended to test the actual frequency of SCL. And observe the value of PRESCALE during debug.

HAPPY NEW YEAR!

Best Regards,
Robin

Re: S32K312 - How can I set I2C baud rate?

Robin_Shen — Tue, 29 Apr 2025 07:32:49 GMT

Hi SEAN SUNG,

Sorry, my previous reply was wrong.
I2c Baud Rate is calculated according to the Lpi2c Module Clock Frequency, not according to the Source in Clock Tools.

Since you selected AIPS_PLAT_CLK for McuClockReferencePoint_0, but the MODULE_CLK of LPI2C should be AIPS_SLOW_CLK. This caused S32 Configuration Tool to incorrectly calculate the baud rate of LPI2C using AIPS_SLOW_CLK.

Sorry, S32 Configuration Tool does not check whether the customer selection complies with Table 117.Communication module clocking in S32K3XXRM.

Best Regards,
Robin

Re: S32K312 - How can I set I2C baud rate?

ssean — Tue, 29 Apr 2025 07:45:40 GMT

@Robin_Shen

Thank you for support.

I'll check again according your guide.

BRs,

Sean Sung