From fdec73848574e0c43c1071b46e184772a84793ac Mon Sep 17 00:00:00 2001
From: Kilrah <kilrah@andrebernet.ch>
Date: Wed, 8 Nov 2017 13:02:32 +0100
Subject: [PATCH] Prevent lockup on boot in case of 32kHz oscillator failure
 (fix #5294)

---
 radio/src/targets/common/arm/stm32/rtc_driver.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/radio/src/targets/common/arm/stm32/rtc_driver.cpp b/radio/src/targets/common/arm/stm32/rtc_driver.cpp
index 486662713..84c9bef5b 100644
--- a/radio/src/targets/common/arm/stm32/rtc_driver.cpp
+++ b/radio/src/targets/common/arm/stm32/rtc_driver.cpp
@@ -64,7 +64,15 @@ void rtcInit()
   RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE);
   PWR_BackupAccessCmd(ENABLE);
   RCC_LSEConfig(RCC_LSE_ON);
-  while(RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET);
+  
+  // Prevent lockup in case of 32kHz oscillator failure
+  uint32_t i = 0;
+  while(RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET)
+  {
+    if ( ++i > 1000000 )
+      return;
+  }
+  
   RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);
   RCC_RTCCLKCmd(ENABLE);
   RTC_WaitForSynchro();