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How to use ETM on-chip

Gpeti
Senior II

Hello,

I'm trying to record the execution trace of my firmware running on a STM32H753. For this I'm using the ETM functionality of Cortex M7. I don't want to use external tools but rather to use the ETF (Embedded Trace FIFO) that can be accessed directly from the processor.

I have been struggling to understand how the different debug components (ETM, ETF, DWT, etc...) are working together. i've read STM32H7 reference manual, ARM ETM technical ref manual and architecture spec but all these debug components are particularly confusing and unclear.

My understanding is that the DWT peripheral compares the execution address and triggers the ETM if it matches. Then the ETM feeds the ETF (?).

Here is the code:

// enable DWT in Debug Exception and Monitor Control Register
 
    *DEMCR |= 1  "the CMPMATCH[N] signals 
 
    // from the DWT unit are available as control inputs to the ETM unit"
 
    *DWT_COMP0 = 0x00000000; // adress comparator
 
    *DWT_MASK0 = 24;
 
    *DWT_FUNCT0 = 0x00000008; // generate CMPMATCH[0] event
 
 
 
    // setup ETM
 
    *ETM_LAR  = 0xC5ACCE55;   // unlock periph
 
    *ETM_CONFIG = (*ETM_CONFIG) | 0x00031F30; // enable all traces
 
    *ETM_PRGCTRL = 1; // enable ETM
 
 
    // setup ETF (by default in circular mode)
 
    *ETF_LAR  = 0xC5ACCE55; // unlock periph
 
    *ETF_FFCR = 0x00001123; // ARM recommends to set bits TRIGONTRIGIN FONTRIGEVT STOPONFL ENTI AND ENFT
 
    *ETF_TRG = 16; // number of 32 words to capture
 
    *ETF_CTL = 1; // enable trace
 
 
    // ******** processing just to fill the trace
 
    U4_INDEX = 1000;
 
    while(U4_INDEX--)
 
      __asm("nop"); 
 
 
    // wait for bit READY
 
    while ( ((*ETF_STS) & (1<<2)) == 0 );
 
        // read trace
        printf("*ETF_RRD=0x%x\r\n", *ETF_RRD);
        printf("*ETF_RRD=0x%x\r\n", *ETF_RRD);
        printf("*ETF_RRD=0x%x\r\n", *ETF_RRD);
        printf("*ETF_RRD=0x%x\r\n", *ETF_RRD);
 
        *ETF_CTL = 0; // disable trace
 
The READY bit of ETF_STS is never rising.
 
 
My question is: how to setup the different debug components to launch the trace execution (to record instructions) ?

My question is: how to setup the different debug components to launch the trace execution (to record instructions) ?

PS: sorry for the bad formatting, it's impossible to remove

1 REPLY 1
AMera.1
Associate

Hi, is there any update on this topic?, I am willing to collaborate to solve this issue.