topic KE02 SPI Documentation in Kinetis Microcontrollers

KE02 SPI Documentation

RobertoPaolinel — Thu, 01 Sep 2016 10:32:47 GMT

Hello,

2 issues on KE02 SPI reference manual I don't understand:

1) SPIx_S[MODF]: What content should I write in C1?

2) SPIx_S[SPMF]

The problem is that register is read only, as stated here.

So, how can I clear SPMF?

Best Regards

Roberto

Re: KE02 SPI Documentation

isaacavila — Mon, 02 Nov 2020 13:46:13 GMT

Hello Roberto,

In order to clear SPIx_S[MODF] flag you need to write any value that you want to SPIx_C1 register, I would suggest to set the SPIx_C1[MSTR] bit due when MODF bit is set, SPI module is configured as slave and MSTR value is cleared, so you can enable this bit again:

if (SPI0->S & SPI_S_MODF_MASK)
{    
    uint8_t temp = SPI0->C1 | SPI_C1_MSTR_MASK;
    SPI0->C1 =  temp;
}‍‍‍‍‍‍‍‍‍‍

Or simply:

if (SPI0->S & SPI_S_MODF_MASK)
{
    SPI0->C1 |= SPI_C1_MSTR_MASK;
}‍‍‍‍

Remember that in order to clear this flag, MODF condition must be removed (SS input should detect a high level voltage), otherwise, this MODF flag won't be cleared.

In Kinetis Family, some flags need to be written by '1' in order to clear them, in this case, you need to modify the MKE02Zx.h file and add the _IO feature in the SPI_S register:

This way you will be able to write to this register and clear the flag:

if (SPI0->S & SPI_S_SPMF_MASK)
{
    SPI0->S |= SPI_S_SPMF_MASK;
}‍‍‍‍

I hope this can help you!

Have a nice day!

Regards,

Isaac

Re: KE02 SPI Documentation

RobertoPaolinel — Thu, 08 Sep 2016 07:59:39 GMT

Hi Isaac,

thanks a lot.

First issue is OK.

About second one: from SW point of view declaring __IO instead of __I will solve.

But from MCU side, its reference manual is reporting that SPI0_S is read only. Sometimes I used to read w1c (write 1 clear): is it just a documentation issue?

Thank you very much

Best Regards

Roberto

Re: KE02 SPI Documentation

isaacavila — Thu, 08 Sep 2016 15:26:04 GMT

Hello Roberto,

It seems to me that this is a documentation error and I need to validate it with Documentation team. Because when I modified the const modifier in the header file, flag could be cleared correctly.

I hope this help

Regards,
Isaac