KL27 I2C Speed Problem

philhale — Wed, 09 May 2018 00:42:51 GMT

I am not quite getting the initialization of the I2C baud rate. Normally, I use the same speed of I2C for all my projects so this is never an issue. Now, I am using an SDK from somebody and they want to set their own I2C speeds for their ICs.

See attached I2C.c file.

I have "acquired" this code from the KDS 2.0 SDK library - or at least it is close. Copyright preserved. :smileywink:

My MCU is a: MKL27Z256VFM4

System Bus Speed: 48 MHz

I am not able to get the speeds I need when I put this on the scope. Not even close.

It seems pretty clunky to get the I2Cx_F settings this way but I'm sure there is a good reason.

I am also getting locking up when in I2C wait states when using the setting suggested for 20 kbps.

I have read the double-buffering causes lock ups at these slower speeds. But, the SDI I am using from this vendor is hardcoding a rate of 20 kbps. Even when I override the inbound 20 kbps to 50 kbps the problem still occurs.

Any suggestions?

Thanks in advance.

Phil

Re: KL27 I2C Speed Problem

philhale — Wed, 09 May 2018 01:25:48 GMT

Can you suggest a good I2C0_F setting for 20, 40, 100, and 400 kbps?

Re: KL27 I2C Speed Problem

jingpan — Wed, 09 May 2018 09:06:27 GMT

Hi,

It is obviously that your SDK is not the most update one. I use SDK 2.3 and the code is different with yours. Please try the example frdmkl27z_driver_example_i2c_i2c_example. You can modify masterConfig.baudRate_Bps as you wish.

Regards,

Jing

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KL27 I2C Speed Problem

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Re: KL27 I2C Speed Problem