From ee3ef1927d310588e3a90af47d9834e589499793 Mon Sep 17 00:00:00 2001
From: Semjon Kerner <semjon.kerner@fu-berlin.de>
Date: Wed, 14 Nov 2018 12:46:02 +0100
Subject: [PATCH] cpu/nrf5x: fix event hang

---
 cpu/nrf5x_common/periph/hwrng.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/cpu/nrf5x_common/periph/hwrng.c b/cpu/nrf5x_common/periph/hwrng.c
index 520d4572a0..5bdc6b8346 100644
--- a/cpu/nrf5x_common/periph/hwrng.c
+++ b/cpu/nrf5x_common/periph/hwrng.c
@@ -39,6 +39,7 @@ void hwrng_read(void *buf, unsigned int num)
 #ifdef CPU_FAM_NRF51
     NRF_RNG->POWER = 1;
 #endif
+    NRF_RNG->INTENSET = RNG_INTENSET_VALRDY_Msk;
     NRF_RNG->TASKS_START = 1;
 
     /* read the actual random data */
@@ -51,9 +52,11 @@ void hwrng_read(void *buf, unsigned int num)
         b[count++] = (uint8_t)NRF_RNG->VALUE;
         /* NRF51 PAN #21 -> read value before clearing VALRDY */
         NRF_RNG->EVENTS_VALRDY = 0;
+        NVIC_ClearPendingIRQ(RNG_IRQn);
     }
 
     /* power off RNG */
+    NRF_RNG->INTENCLR = RNG_INTENSET_VALRDY_Msk;
     NRF_RNG->TASKS_STOP = 1;
 #ifdef CPU_FAM_NRF51
     NRF_RNG->POWER = 0;