Random number generator hanging on TRNG_EV_VALRDY

Question

Here is my function to generate random numbers of desired length. 
 #define TRNG_BASE 0x4000D000
#define TRNG_TASKS_START (*(volatile uint32_t *)(TRNG_BASE + 0x000))
#define TRNG_TASKS_STOP (*(volatile uint32_t *)(TRNG_BASE + 0x004))
#define TRNG_EV_VALRDY (*(volatile uint32_t *)(TRNG_BASE + 0x100))
#define TRNG_VALUE (*(volatile uint32_t *)(TRNG_BASE + 0x508))

void sys_random(uint8_t *buf, int len)
{
 volatile uint8_t val;
 volatile int i = 0;
 /* Clear VALRDY */
 TRNG_EV_VALRDY = 0;
 /* Start TRNG */
 TRNG_TASKS_START = 1;
 for (i = 0; i < len; i++)
 {
 printf("Generating random #%d
", i);
 
 /* Wait until value ready */
 while (TRNG_EV_VALRDY == 0);
 
 TRNG_EV_VALRDY = 0;
 buf[i] = (uint8_t)(TRNG_VALUE & 0x000000FF);
 }
 TRNG_TASKS_STOP |= 1;
}
 
 After generating a few(5 to 6) random numbers the function hangs at while (TRNG_EV_VALRDY == 0) . 
 I am using RIOT OS on nrf52832. What could be the issue here?

Prasad · Accepted Answer

I managed to solve it this way... 
 void sys_random(uint8_t *buf, int len)
 {
 uint8_t val;
@@ -36,11 +38,14 @@ void sys_random(uint8_t *buf, int len)
 /* Start TRNG */
 TRNG_TASKS_START = 1;
 for (i = 0; i < len; i++) {
 /* Wait until value ready */
 while (TRNG_EV_VALRDY == 0)
 ;
- buf[i] = (uint8_t)(TRNG_VALUE & 0x000000FF);
 TRNG_EV_VALRDY = 0;
+ buf[i] = (uint8_t)(TRNG_VALUE & 0x000000FF);
+ TRNG_TASKS_START = 1;
 }
 TRNG_TASKS_STOP |= 1;
 }
 
 This should reinit the RNG after every random number generation.

Random number generator hanging on TRNG_EV_VALRDY

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