From 31719589b2ebf570ca4702a1c05b0d7ad2b990ce Mon Sep 17 00:00:00 2001
From: Cristian Maglie <c.maglie@bug.st>
Date: Fri, 21 Sep 2012 11:50:52 +0200
Subject: [PATCH] Fixed micros()-not-monothonic bug

---
 hardware/arduino/sam/cores/arduino/wiring.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/hardware/arduino/sam/cores/arduino/wiring.c b/hardware/arduino/sam/cores/arduino/wiring.c
index 5de053a1e..ce3f798ac 100644
--- a/hardware/arduino/sam/cores/arduino/wiring.c
+++ b/hardware/arduino/sam/cores/arduino/wiring.c
@@ -31,13 +31,16 @@ uint32_t millis( void )
 
 uint32_t micros( void )
 {
-  uint32_t dwTicks ;
+    uint32_t ticks ;
+    uint32_t count ;
 
-  __disable_irq() ;
-  dwTicks=SysTick->VAL ;
-  __enable_irq() ;
+    SysTick->CTRL;
+    do {
+        ticks = SysTick->VAL;
+        count = GetTickCount();
+    } while (SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk);
 
-  return (GetTickCount()*1000) + ((SysTick->LOAD + 1 - dwTicks)/(SystemCoreClock/1000000)) ;
+    return count * 1000 + (SysTick->LOAD + 1 - ticks) / (SystemCoreClock/1000000) ;
 }
 
 void delay( uint32_t dwMs )