NRF52840: Using the CryptoCell310 with a preemptive OS

[DamianV]

Hi,

I need to use the cryptocell in a project with a preemptive OS. Are there any relevant code examples  available, or at least some general guidelines and precautions (e.g., for the initialization of the cryptocell)?

Thanks,

Damian

[Rudy U]

Hi Damian and Jean-Marc,

We are facing the same problem with FreeRtos and the BLE stack. The CC310 is hanging in the SaSi_HalWaitInterrupt. 

How did you manege to mask the interrupts? Could you post a snippet of the code or point us in the right direction

Thanks in advance,

Rudy

[Jean-Marc Koller]

Some time after the initial post, I noticed that, in the SDK 15.3, another CC310 library made its appearance: a new folder named "no-interrupts" with a .a file in it. After switching to this library, we didn't experience any problems related to the CC310 and external interrupts. The backside might be that the current consumption might be a bit higher as the processor will actively wait for the crypto-cell to finish, but the CC310 operations are mostly quite short.

[Rudy U]

Thanks for your quick response, Jean-Marc. We have tried the no interrupt library and it seems to be working fine. I guess that why Nordic made this library for the Rtos. Hopefully they fix this interrupt issue in the future :-)

yours sincerely,

Rudy

[Red_devil]

Hi Jean,

I tried the above mentioned solution. I am facing the same issue even after adding "no-interrupts" library.

[WilliamEriksson]

Hi, although a little late here is a snippet that worked for me to mask the basepri:

NVIC_EnableIRQ(CRYPTOCELL_IRQn);
NRF_CRYPTOCELL->ENABLE = 1;

SaSi_LibInit();

/* First read the current basepri value */
uint32_t prevBasepri = __get_BASEPRI();

/* Mask (disable) all interrupts with priority greater or equal to 1 */
__set_BASEPRI( 1 << ( 8 - __NVIC_PRIO_BITS) );

CRYS_RndInit(&state, &buf);

/* Restore the previous basepri */
__set_BASEPRI(prevBasepri);

Related reading where I also posted the snippet:

https://devzone.nordicsemi.com/f/nordic-q-a/45500/nrf52840-and-cc310-random-number-generator-hanging/179450?focus=true