43.3.3.1 Initializing the PUKCC and PUKCL

For a project created with Atmel START, the clock initialization is handled by the initialization function atmel_start_init. After a power-on reset, and when the PUKCC Clock is enabled, a Crypto RAM clear process is launched. It is mandatory to wait until the end of this process before using the Crypto Library.

The following code shows how to wait for the Crypto RAM clear process.

while ((PUKCCSR & BIT_PUKCCSR_CLRRAM_BUSY) != 0);

The next task to be done is self-test. From the generated project in Atmel Studio, copy the example for the PUKCC Driver SelfTest and add it to the main source file. This is a mandatory step before using the library. The return values from the SelfTest service must be compared against known values mentioned in the service description (see the Description section in SelfTest).

void PUKCC_self_test(void)
{
    // Clear contents of PUKCLParam
    memset(&PUKCLParam, 0, sizeof(PUKCL_PARAM));

    pvPUKCLParam = &PUKCLParam;
    vPUKCL_Process(SelfTest, pvPUKCLParam);

    // In case of error, loop here
    while (PUKCL(u2Status) != PUKCL_OK) {
    ;
    }
    while (pvPUKCLParam->P.PUKCL_SelfTest.u4Version != PUKCL_VERSION) {
    ;
    }
    while (pvPUKCLParam->P.PUKCL_SelfTest.u4CheckNum1 != 0x6E70DDD2) {
    ;
    }
    while (pvPUKCLParam->P.PUKCL_SelfTest.u4CheckNum2 != 0x25C8D64F) {
    ;
    }
}

int main(void)
{
    /* Initializes MCU, drivers and middleware */    
    atmel_start_init();
	
    // Wait for Crypto RAM clear process
    while ((PUKCCSR & BIT_PUKCCSR_CLRRAM_BUSY) != 0);

    // Initialize PUKCC and perform self test
    PUKCC_self_test();
    while(1)
    {
    }
}