From 8ab9956ae5b88bf7ff4f99eda14acdd46b136732 Mon Sep 17 00:00:00 2001
From: crasbe <crasbe@gmail.com>
Date: Thu, 26 Jun 2025 15:49:29 +0200
Subject: [PATCH 1/2] sys/net/sntp: migrate from xtimer to ztimer

---
 sys/Makefile.dep                      |  7 ++-----
 sys/include/net/sntp.h                | 11 ++++++++---
 sys/net/application_layer/sntp/sntp.c |  4 ++--
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/sys/Makefile.dep b/sys/Makefile.dep
index b15de27334..5ae9ae3abe 100644
--- a/sys/Makefile.dep
+++ b/sys/Makefile.dep
@@ -134,11 +134,8 @@ endif
 
 ifneq (,$(filter sntp,$(USEMODULE)))
   USEMODULE += sock_udp
-  USEMODULE += xtimer
-  ifneq (,$(filter ztimer_xtimer_compat,$(USEMODULE)))
-    # requires 64bit ftimestamps
-    USEMODULE += ztimer64_xtimer_compat
-  endif
+  USEMODULE += ztimer64
+  USEMODULE += ztimer64_usec
 endif
 
 ifneq (,$(filter sock_%,$(USEMODULE)))
diff --git a/sys/include/net/sntp.h b/sys/include/net/sntp.h
index 226756b3d2..e6fc1ce6bc 100644
--- a/sys/include/net/sntp.h
+++ b/sys/include/net/sntp.h
@@ -15,6 +15,10 @@
  * @brief       Simple Network Time Protocol (SNTP) implementation
  * @{
  *
+ * @note        The current implementation of SNTP uses @ref sys_ztimer64 with
+ *              microsecond accuracy, which can have a strong impact on
+ *              the power consumption of your device.
+ *
  * @file
  * @brief       SNTP definitions
  *
@@ -27,7 +31,7 @@
 
 #include "net/ntp_packet.h"
 #include "net/sock/udp.h"
-#include "xtimer.h"
+#include "ztimer64.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -45,7 +49,7 @@ extern "C" {
 int sntp_sync(sock_udp_ep_t *server, uint32_t timeout);
 
 /**
- * @brief Get real time offset from system time as returned by @ref xtimer_now64()
+ * @brief Get real time offset from system time as returned by @ref ztimer64_now()
  *
  * @return Real time offset in microseconds relative to 1900-01-01 00:00 UTC
  */
@@ -58,7 +62,8 @@ int64_t sntp_get_offset(void);
  */
 static inline uint64_t sntp_get_unix_usec(void)
 {
-    return (uint64_t)(sntp_get_offset() - (NTP_UNIX_OFFSET * US_PER_SEC) + xtimer_now_usec64());
+    return (uint64_t)(sntp_get_offset() - (NTP_UNIX_OFFSET * US_PER_SEC) + \
+                      ztimer64_now(ZTIMER64_USEC));
 }
 
 #ifdef __cplusplus
diff --git a/sys/net/application_layer/sntp/sntp.c b/sys/net/application_layer/sntp/sntp.c
index ec6ee6b5b0..48a24512d1 100644
--- a/sys/net/application_layer/sntp/sntp.c
+++ b/sys/net/application_layer/sntp/sntp.c
@@ -22,7 +22,7 @@
 #include "net/sntp.h"
 #include "net/ntp_packet.h"
 #include "net/sock/udp.h"
-#include "xtimer.h"
+#include "ztimer64.h"
 #include "mutex.h"
 #include "byteorder.h"
 
@@ -70,7 +70,7 @@ int sntp_sync(sock_udp_ep_t *server, uint32_t timeout)
     mutex_lock(&_sntp_mutex);
     _sntp_offset = (((int64_t)byteorder_ntohl(_sntp_packet.transmit.seconds)) * US_PER_SEC) +
                    ((((int64_t)byteorder_ntohl(_sntp_packet.transmit.fraction)) * 232)
-                   / 1000000) - xtimer_now_usec64();
+                   / 1000000) - ztimer64_now(ZTIMER64_USEC);
     mutex_unlock(&_sntp_mutex);
     return 0;
 }

From acf10d91b97f35c2930481264823bf37e5ee6dce Mon Sep 17 00:00:00 2001
From: crasbe <crasbe@gmail.com>
Date: Thu, 21 Aug 2025 14:20:26 +0200
Subject: [PATCH 2/2] sys/net/ntp_packet: add ref to SNTP, fix time

---
 sys/include/net/ntp_packet.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sys/include/net/ntp_packet.h b/sys/include/net/ntp_packet.h
index 99ef72f624..9bb0dc8dd8 100644
--- a/sys/include/net/ntp_packet.h
+++ b/sys/include/net/ntp_packet.h
@@ -14,6 +14,8 @@
  * @brief       The NTP packet module provides functionality to manipulate the NTP header
  * @{
  *
+ * @see         An implementation of Simple NTP can be found in @ref net_sntp.
+ *
  * @file
  * @brief       NTP packet definitions
  *
@@ -46,7 +48,7 @@ extern "C" {
 #define NTP_PORT             (123U)     /**< NTP port number */
 
 /**
- * @brief   Offset in seconds of NTP timestamp (seconds from 1990-01-01 00:00:00 UTC)
+ * @brief   Offset in seconds of NTP timestamp (seconds from 1900-01-01 00:00:00 UTC)
  *          to UNIX timestamp (seconds from 1970-01-01 00:00:00 UTC).
  */
 #define NTP_UNIX_OFFSET      (2208988800)