From d816666d84025b55a1b9aef569ed82c5034d6d8f Mon Sep 17 00:00:00 2001
From: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Date: Tue, 30 Mar 2021 14:49:11 +0200
Subject: [PATCH] cpu/sam3/periph_rtt: fix rtt_get_alarm()

Previously, the return value was off by one.
---
 cpu/sam3/periph/rtt.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/cpu/sam3/periph/rtt.c b/cpu/sam3/periph/rtt.c
index 2c7d0da245..2da87e712c 100644
--- a/cpu/sam3/periph/rtt.c
+++ b/cpu/sam3/periph/rtt.c
@@ -75,7 +75,8 @@ void rtt_set_alarm(uint32_t alarm, rtt_cb_t cb, void *arg)
 uint32_t rtt_get_alarm(void)
 {
     if (RTT->RTT_MR & RTT_MR_ALMIEN) {
-        return RTT->RTT_AR;
+        /* the alarm value is RTT_AR + 1, see rtt_set_alarm() */
+        return RTT->RTT_AR + 1;
     }
     return 0;
 }