From 6c6df28b856c4a7e58bc2d642f5992e677459109 Mon Sep 17 00:00:00 2001
From: daijoubu <daijoubu@gmail.com>
Date: Tue, 9 Jun 2026 19:54:27 -0700
Subject: [PATCH] fix(gps): clamp negative uBlox nano field before millis
 conversion
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The nano field in UBX-NAV-TIMEUTC and UBX-NAV-PVT messages is int32_t
and legitimately goes negative near second boundaries. Dividing without
clamping produced a large positive uint16_t (e.g. -50ms → 65486 ms),
setting the RTC ~64 seconds fast on first GPS lock. Once set, rtcHasTime()
prevents correction until reboot.

Clamp to zero before the division on both message handlers.
---
 src/main/io/gps_ublox.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main/io/gps_ublox.c b/src/main/io/gps_ublox.c
index 4fd0c332a21..95feedabb6c 100755
--- a/src/main/io/gps_ublox.c
+++ b/src/main/io/gps_ublox.c
@@ -635,7 +635,7 @@ static bool gpsParseFrameUBLOX(void)
             gpsSolDRV.time.hours = _buffer.timeutc.hour;
             gpsSolDRV.time.minutes = _buffer.timeutc.min;
             gpsSolDRV.time.seconds = _buffer.timeutc.sec;
-            gpsSolDRV.time.millis = _buffer.timeutc.nano / (1000*1000);
+            gpsSolDRV.time.millis = (uint16_t)(MAX(0, _buffer.timeutc.nano) / (1000*1000));
 
             gpsSolDRV.flags.validTime = true;
         } else {
@@ -674,7 +674,7 @@ static bool gpsParseFrameUBLOX(void)
             gpsSolDRV.time.hours = _buffer.pvt.hour;
             gpsSolDRV.time.minutes = _buffer.pvt.min;
             gpsSolDRV.time.seconds = _buffer.pvt.sec;
-            gpsSolDRV.time.millis = _buffer.pvt.nano / (1000*1000);
+            gpsSolDRV.time.millis = (uint16_t)(MAX(0, _buffer.pvt.nano) / (1000*1000));
 
             gpsSolDRV.flags.validTime = true;
         } else {