TRNG Interface

Driver API for TRNG (plib_trng.h) More...

Typedefs
typedef void(*	TRNG_CALLBACK) (uint32_t random_value)
	Function pointer type for the TRNG Data Ready callback.

Functions
void	TRNG_Enable (void)
	Enables the TRNG peripheral.
void	TRNG_Disable (void)
	Disables the TRNG peripheral.
bool	TRNG_DataIsReady (void)
	Checks whether a new random value is available.
bool	TRNG_GetRandomNumber (uint32_t *data)
	Reads a random 32-bit value from the TRNG peripheral.
void	TRNG_EnableInterrupt (void)
	Enables the TRNG Data Ready interrupt.
void	TRNG_DisableInterrupt (void)
	Disables the TRNG Data Ready interrupt.
bool	TRNG_InterruptIsEnabled (void)
	Checks whether the Data Ready interrupt is enabled.
void	TRNG_SetCallbackHandler (TRNG_CALLBACK callback)
	Registers the callback invoked from TRNG_Handler() on Data Ready.

Description

Driver API for TRNG (plib_trng.h)

Usage Example

The following example demonstrates typical usage of the TRNG peripheral:

/*******************************************************************************
 * @file configure_trng.c
 * @brief TRNG interrupt-driven configuration template
 *
 * @details
 * The TRNG is a hardware entropy source with no seed and no configurable
 * parameters: software only controls whether the peripheral is running
 * (TRNG_CR.ENABLE) and whether Data Ready raises an interrupt (TRNG_IER).
 *
 * In this template:
 * - The callback is registered and the Data Ready interrupt is armed
 *   before the peripheral is enabled, so no word can be missed.
 * - No warm-up delay is added: every read path gates on TRNG_ISR.DATRDY,
 *   which cannot assert before TRNGWUP has elapsed.
 * - Data Ready re-asserts every ~84 clock cycles until disabled. The
 *   callback only stores the word; the application calls
 *   TRNG_DisableInterrupt() when it has collected enough.
 * - The NVIC line is left masked; the application enables it (see
 *   app_plib.c) so it owns the TRNG interrupt priority.
 ******************************************************************************/
#include "plib_trng.h"
#include <stdint.h>
#include <stdbool.h>
 
/* Raised by the callback for the application to consume. */
volatile bool     trng_data_ready  = false;
volatile uint32_t trng_last_value  = 0U;
 
/* Data Ready callback, invoked from TRNG_Handler() in interrupt context */
void TRNG_DataReadyCallback(uint32_t random_value)
{
    trng_last_value = random_value;
    trng_data_ready  = true;
}
 
int32_t configure_trng(void)
{
    /* Start from a known state. */
    TRNG_DisableInterrupt();
    TRNG_Disable();
    TRNG_SetCallbackHandler(NULL);
 
    /* Arm the callback and Data Ready before the peripheral runs. */
    TRNG_SetCallbackHandler(&TRNG_DataReadyCallback);
    TRNG_EnableInterrupt();
 
    /* Start the entropy source. */
    TRNG_Enable();
 
    return 0;
}

Typedef Documentation

TRNG_CALLBACK

typedef void(* TRNG_CALLBACK) (uint32_t random_value)

Function pointer type for the TRNG Data Ready callback.

Parameters

random_value

The 32-bit random value read from TRNG_ODATA.

Function Documentation

TRNG_DataIsReady()

bool TRNG_DataIsReady

(

void

)

Checks whether a new random value is available.

Returns

true if a random value is ready to be read, false otherwise.

Note

TRNG_ISR.DATRDY is cleared by hardware on read. TRNG_DataIsReady() and TRNG_GetRandomNumber() share an internal latch so a pending value is never lost between them.

TRNG_Disable()

void TRNG_Disable

(

void

)

Disables the TRNG peripheral.

Returns

None.

TRNG_DisableInterrupt()

void TRNG_DisableInterrupt

(

void

)

Disables the TRNG Data Ready interrupt.

Returns

None.

TRNG_Enable()

void TRNG_Enable

(

void

)

Enables the TRNG peripheral.

Returns

None.

Note

Wait for the TRNG Warm-Up Time (TRNGWUP), per the AC electrical timings, before reading random data.

TRNG_EnableInterrupt()

void TRNG_EnableInterrupt

(

void

)

Enables the TRNG Data Ready interrupt.

Returns

None.

Note

Fires every 84 clock cycles until disabled; TRNG_Handler() does not disable it automatically. Register a callback first, or each word is discarded. Do not call TRNG_GetRandomNumber() while enabled; both read TRNG_ISR destructively.

TRNG_GetRandomNumber()

bool TRNG_GetRandomNumber

(

uint32_t *

data

)

Reads a random 32-bit value from the TRNG peripheral.

Parameters

[out]

data

Pointer to store the random value.

Returns

true if a value was read into *data, false if data is NULL or no value was ready.

TRNG_InterruptIsEnabled()

bool TRNG_InterruptIsEnabled

(

void

)

Checks whether the Data Ready interrupt is enabled.

Returns

true if TRNG_IMR.DATRDY is set, false otherwise.

TRNG_SetCallbackHandler()

void TRNG_SetCallbackHandler

(

TRNG_CALLBACK

callback

)

Registers the callback invoked from TRNG_Handler() on Data Ready.

Parameters

callback

Pointer to the callback function (NULL to clear).

Returns

None.