TRNG driver

TRNG driver implementation for a CC26XX device. More...

Modules
	TRNG_STATUS

Files
file	TRNGCC26XX.h
	TRNG driver implementation for a CC26XX device.

Macros
#define	TRNGCC26XX_CLOCKS_PER_SAMPLES_MAX   15
#define	TRNGCC26XX_MAX_SAMPLES_MAX   16777216
#define	TRNGCC26XX_MAX_SAMPLES_MIN   256
#define	TRNGCC26XX_MIN_SAMPLES_MAX   16384
#define	TRNGCC26XX_MIN_SAMPLES_MIN   64

Detailed Description

TRNG driver implementation for a CC26XX device.

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Driver Include

The TRNG header file should be included in an application as follows:

#include <ti/drivers/trng/TRNGCC26XX.h>

Overview

The TRNGCC26XX driver provides reentrant access to the TRNG module within the CC26XX. Reentrant access is controlled by creating a global critical section when requesting a random number. This critical section disables all Hwi's from running.

General Behavior

Initialing the TRNGCC26XX Driver

• TRNGCC26XX_init must be called prior to calling any other TRNGCC26xx API.
• This function need only be called once per reset, but may be called multiple times without affect.

Opening the TRNGCC26XX Driver

• TRNGCC26XX_open is used to open the driver prior to requesting a number.
• This function powers on the TRNG peripheral.
• Calling this function is optional, but will increase the latency of the first call to TRNGCC26XX_getNumber().
• This function need only be called once per reset, but may be called multiple times without affect.

// Open the driver
TRNGCC26XX_open(Board_TRNG);

Initializing client parameters

• Client parameters are optional. The Driver may be called with a NULL pointer to the client parameters, in which case it will use the default parameters. The default parameters configurate the TRNG to produce 256 samples per cycle at 1 clock per sample. a call to TRNGCC26XX_getNumber with default values has a latency of 14us. Increasing any of the configuration parameters will result in an increase in latency.
• The application initializes its parameters by calling TRNGCC26XX_Params_init() and passing a pointer to a TRNGCC26XX_Params variable as an argument to it.
• This function can be called once or more to each initialization of parameters.
• This function can be called once or more with the same TRNGCC26XX_Params variable.
• The client parameter are initialized to valid default values, but may be changed by the client after this function returns. See trng.h for full details.

TRNGCC26XX_Params trngParams;

// Initialize parameters.
TRNGCC26XX_Params_init(&trngParams);

// Optionally modify trngParams
...

Validating client parameters

• a client may optionally choose to validate its configuration parameters before attempting to generate a number.
• when a client passes configuration parameters to TRNGCC26XX_getNumber these parameters will automatically be checked.

TRNGCC26XX_Params trngParams;

// Initialize parameters.
TRNGCC26XX_Params_init(&trngParams);

// Set client parameters.
trngParams.minSamplesPerCycle = 256;
trngParams.maxSamplesPerCycle = 256;
trngParams.clocksPerSample = 1;

// Validate parameters.
if (TRNGCC26XX_isParamValid(&trngParams) == TRNGCC26XX_STATUS_SUCCESS)
{
   // Parameters are valid.
}

Generating a random number

• The TRNG may be called without client configuration parameters and pass a NULL pointer as an argument instead. This will result in the default values being used.
• Using the initialized client configuration parameters, a random number can be generated.
• an optional status flag pointer may be passed as an argument to check if the call successfully generated a random number.

TRNGCC26XX_Params trngParams;
uint8_t trngStatusFlag;
uint32_t trngNum1;
uint32_t trngNum2;

// Init driver.
TRNGCC26XX_init();

// Open TRNG peripheral.
TRNGCC26XX_open(Board_TRNG);

// Initialize parameters.
TRNGCC26XX_Params_init(&trngParams);

// Generate a random number.  Use optional status flag.
trngNum1 = TRNGCC26XX_getNumber(&trngParams, &trngStatusFlag);

// Check if status was okay
if (trngStatusFlag == TRNGCC26XX_STATUS_SUCCESS)
{
  // Random number was generated successfully
}

// Generate a second random number using the default values and no
// status flag.
trngNum2 = TRNGCC26XX_getNumber(NULL, NULL);

Supported transaction modes

• all calls to TRNGCC26XX_getNumber are blocking until the TRNG has a new random number available.

Error handling

If an error occurs during a call to TRNGCC26XX_getNumber, the error status will be set into the status flag and the returned random number shall be 0. passing the status flag is optional.

Supported Functions

API function	Description
TRNGCC26XX_open()	Open driver (stub)
TRNGCC26XX_close()	Close driver (stub)
TRNGCC26XX_Params_init()	Initialize parameters for random number generation
TRNGCC26XX_init()	Generates a random number
TRNGCC26XX_isParamValid	Validate client configuration parameters

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Macro Definition Documentation

TRNGCC26XX_CLOCKS_PER_SAMPLES_MAX

#define TRNGCC26XX_CLOCKS_PER_SAMPLES_MAX   15

Number of clocks cycles per sample must be between 1 (0) and 16 (15), inclusive.

TRNGCC26XX_MAX_SAMPLES_MAX

#define TRNGCC26XX_MAX_SAMPLES_MAX   16777216

Largest allowable maximum samples count per cycle

TRNGCC26XX_MAX_SAMPLES_MIN

#define TRNGCC26XX_MAX_SAMPLES_MIN   256

Maximium samples per cycle range. Maximium may be 0, or greater than or equal to 2^8 and less than or equal to 2^24.Smallest allowable maximum samples count per cycle

TRNGCC26XX_MIN_SAMPLES_MAX

#define TRNGCC26XX_MIN_SAMPLES_MAX   16384

Largest allowable minimum samples count per cycle

TRNGCC26XX_MIN_SAMPLES_MIN

#define TRNGCC26XX_MIN_SAMPLES_MIN   64

Minimum samples per cycle range, minimum value

Minimum may be 0, or greater than or equal to 2^6 and less than 2^14.Smallest allowable minimum samples count per cycle