Data Serialization

yashkumar — Thu, 31 Aug 2017 18:56:30 GMT

Hi,

I am working on data serialization with S32K142/144 micro controller . I am using this controller for CAN specific applications. And in which i realized "data serialization " should restrictively followed .

So,i have gone thorough alot-off posts and documentations.

after all i have still one doubt , as for any peripheral resister access , we should follow "read after write".

As in below example, during accessing of LPTMR0_CSR.

void lptmr_isr(void)

{

// Declare dummy variable to store the read of the LPTMR0_CSR register

volatile int dummy_var

/**** STEP #1 ****/

// Clear the flag; enable interrupts; enable the timer

LPTMR0_CSR = ( LPTMR_CSR_TEN_MASK | LPTMR_CSR_TIE_MASK | LPTMR_CSR_TCF_MASK );

/**** STEP #2 ****/

// Store CSR register in dummy_var to serialize the clearing of the TCF flag

dummy_var = LPTMR0_CSR;

}

But,

1. can we use just memory barrier instruction __asm("dsb"); in place of "dummy_var = LPTMR0_CSR;" instruction ?

2. Is could you please give few example of real time use of __asm("dmb"); __asm("dsb"); __asm("isb"); .

Please help me on this.

Thankyou!

Re: Data Serialization

danielmartynek — Wed, 13 Sep 2017 21:23:57 GMT

Hi,
I had to modify this comment.
DSB instruction serialize all explicit memory accesses.
But it doesn’t serialize peripheral writes, in this case, we need to do Read-After-Write sequence to be sure the writes are complete before we can proceed with execution of subsequent instructions. We can use ISB instruction to flush the pipeline if needed.

Regards,
Daniel

topic Re: Data Serialization in S32K

Data Serialization

Re: Data Serialization