S32KのトピックRe: How does S32K148 LPI2C master support clock stretching feature?

How does S32K148 LPI2C master support clock stretching feature?

Yanzhong — Tue, 14 Mar 2023 03:01:08 GMT

We want to use S32K148 LPI2C to config ADI A2B network, which needs the I2C master to support clock stretching feature. How does S32K148 LPI2C master support clock stretching feature?

Thanks,

Yanzhong Wang

Re: How does S32K148 LPI2C master support clock stretching feature?

danielmartynek — Tue, 14 Mar 2023 08:34:00 GMT

Hi @Yanzhong,

In the master mode, the clock stretching is always enabled.

It follows the I2C specification (UM10204).

In the MCFGR3 register, timeout can be set.

BR, Daniel

Re: How does S32K148 LPI2C master support clock stretching feature?

Yanzhong — Tue, 14 Mar 2023 09:13:05 GMT

Thanks.

The reset value of register MCFGR3 is zero, so the clock stretching is disabled by default. Is it right?

BR,

Yanzhong

Re: How does S32K148 LPI2C master support clock stretching feature?

danielmartynek — Tue, 14 Mar 2023 09:31:55 GMT

No, if set to 0, the timeout feature is disabled, but not the clock stretching:

danielmartynek_0-1678786074279.png

It can be also enabled on SDA in MCFGR1[TIMECFG].

danielmartynek_1-1678786161697.png

Regards,

Daniel

Re: How does S32K148 LPI2C master support clock stretching feature?

Yanzhong — Wed, 15 Mar 2023 06:24:47 GMT

You mean the Pin Low Timeout feature can be used to confirm whether clock stretching is generated?

BR,

Yanzhong

Re: How does S32K148 LPI2C master support clock stretching feature?

danielmartynek — Wed, 15 Mar 2023 09:05:02 GMT

Hello @Yanzhong,

No, the clock stretching is functional by default.

But you can limit the time this way.

BR, Daniel

Re: How does S32K148 LPI2C master support clock stretching feature?

Yanzhong — Wed, 15 Mar 2023 09:58:09 GMT

The Pin Low Timeout feature is disabled by default. So, the time of clock stretching is unlimited, isn't it?

Br,

Yanzhong

Re: How does S32K148 LPI2C master support clock stretching feature?

danielmartynek — Wed, 15 Mar 2023 10:08:15 GMT

yes, that is correct.

Re: How does S32K148 LPI2C master support clock stretching feature?

Yanzhong — Wed, 15 Mar 2023 10:10:24 GMT

Thanks a lot!

Re: How does S32K148 LPI2C master support clock stretching feature?

Yanzhong — Wed, 09 Aug 2023 01:44:57 GMT

Thanks a lot!