dandri/pyxis
1
0
Fork 0
mirror of https://github.com/torlando-tech/pyxis.git synced 2026-08-08 11:49:53 +00:00
Code Issues Actions 4 Packages Projects Releases Wiki Activity

Fix GPS time sync: double-mktime corruption, missing retry, no DST

Browse Source 
Three issues caused wildly incorrect device time:

1. mktime() was called before setting TZ=UTC, corrupting the time
   struct. The second mktime() then operated on mutated values.
   Fix: set TZ=UTC0 before the single mktime() call.

2. GPS cold start takes minutes but boot only waited 15s. If GPS
   missed the window, time was never set. Fix: retry in main loop
   once GPS reports a valid fix.

3. GPS timezone used a raw longitude offset with no DST rules, so
   EDT was shown as EST (off by 1 hour). Fix: use proper POSIX TZ
   strings with DST rules for US timezones.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
torlando-tech
2026-03-06 10:06:05 -05:00
co-authored by Claude Opus 4.6
parent cab566a69e
commit 8d4a047c14
1 changed files with 46 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/main.cpp
+46 -38
View File
@@ -223,27 +223,18 @@ int calculate_timezone_offset_hours(double longitude) {
bool sync_time_from_gps(uint32_t timeout_ms = 30000) {
INFO("Attempting GPS time sync...");
uint32_t start = millis();
bool got_time = false;
bool got_location = false;
// Check if gps object already has valid data (from main loop feeding)
bool got_time = (gps.date.isValid() && gps.time.isValid() && gps.date.year() >= 2024);
bool got_location = gps.location.isValid();
while (millis() - start < timeout_ms) {
// If not ready yet, wait and read serial data
uint32_t start = millis();
while (!(got_time && got_location) && (millis() - start < timeout_ms)) {
while (GPSSerial.available() > 0) {
if (gps.encode(GPSSerial.read())) {
// Check if we have valid date/time
if (gps.date.isValid() && gps.time.isValid() && gps.date.year() >= 2024) {
got_time = true;
}
// Check if we have valid location (for timezone)
if (gps.location.isValid()) {
got_location = true;
}
// If we have both, we can sync
if (got_time && got_location) {
break;
}
}
gps.encode(GPSSerial.read());
}
got_time = (gps.date.isValid() && gps.time.isValid() && gps.date.year() >= 2024);
got_location = gps.location.isValid();
if (got_time && got_location) break;
delay(10);
}
@@ -264,12 +255,11 @@ bool sync_time_from_gps(uint32_t timeout_ms = 30000) {
gps_time.tm_isdst = 0; // GPS time is UTC, no DST
// Convert to Unix timestamp (UTC)
time_t gps_unix = mktime(&gps_time);
// mktime assumes local time, adjust back to UTC
// Actually, we'll set TZ to UTC first
// Set TZ to UTC BEFORE mktime — mktime interprets its argument as local
// time and mutates the struct, so TZ must be correct on the first call.
setenv("TZ", "UTC0", 1);
tzset();
gps_unix = mktime(&gps_time);
time_t gps_unix = mktime(&gps_time);
// Set the system time
struct timeval tv;
@@ -278,31 +268,41 @@ bool sync_time_from_gps(uint32_t timeout_ms = 30000) {
settimeofday(&tv, nullptr);
// Set timezone based on location if available
// Use US timezone with DST rules when in continental US longitude range,
// otherwise fall back to a simple offset without DST.
const char* tz_str = "EST5EDT,M3.2.0,M11.1.0"; // default
if (got_location) {
double longitude = gps.location.lng();
int tz_offset = calculate_timezone_offset_hours(longitude);
// Build POSIX TZ string (e.g., "EST5" for UTC-5)
// Note: POSIX uses opposite sign convention!
char tz_str[32];
if (tz_offset >= 0) {
snprintf(tz_str, sizeof(tz_str), "GPS%d", -tz_offset);
} else {
snprintf(tz_str, sizeof(tz_str), "GPS+%d", -tz_offset);
if (longitude >= -67.0 && longitude < -67.0) // Atlantic: not continental US
tz_str = "AST4ADT,M3.2.0,M11.1.0";
else if (longitude >= -82.5 && longitude < -67.0) // Eastern
tz_str = "EST5EDT,M3.2.0,M11.1.0";
else if (longitude >= -97.5 && longitude < -82.5) // Central
tz_str = "CST6CDT,M3.2.0,M11.1.0";
else if (longitude >= -112.5 && longitude < -97.5) // Mountain
tz_str = "MST7MDT,M3.2.0,M11.1.0";
else if (longitude >= -127.5 && longitude < -112.5) // Pacific
tz_str = "PST8PDT,M3.2.0,M11.1.0";
else {
// Outside US — use simple offset from longitude (no DST)
int tz_offset = calculate_timezone_offset_hours(longitude);
static char tz_buf[32];
if (tz_offset >= 0)
snprintf(tz_buf, sizeof(tz_buf), "GPS%d", -tz_offset);
else
snprintf(tz_buf, sizeof(tz_buf), "GPS+%d", -tz_offset);
tz_str = tz_buf;
}
setenv("TZ", tz_str, 1);
tzset();
String msg = " GPS location: " + String(gps.location.lat(), 4) + ", " + String(longitude, 4);
String msg = " GPS location: " + String(gps.location.lat(), 4) + ", " + String(gps.location.lng(), 4);
INFO(msg.c_str());
msg = " Timezone offset: UTC" + String(tz_offset >= 0 ? "+" : "") + String(tz_offset);
msg = " Timezone: " + String(tz_str);
INFO(msg.c_str());
} else {
// No location, use default Eastern Time
WARNING("GPS location not available, using Eastern Time");
setenv("TZ", "EST5EDT,M3.2.0,M11.1.0", 1);
tzset();
}
setenv("TZ", tz_str, 1);
tzset();
// Set the time offset for Utilities::OS::time()
time_t now = time(nullptr);
@@ -1664,6 +1664,14 @@ void loop() {
gps.encode(GPSSerial.read());
}
// Retry GPS time sync once we get a fix (boot timeout often misses cold start)
if (!gps_time_synced && gps.date.isValid() && gps.time.isValid()
&& gps.date.year() >= 2024 && gps.location.isValid()) {
// Data is already in the gps object from the feed loop above —
// sync_time_from_gps will find it on the first iteration
sync_time_from_gps(1000);
}
// Screen timeout handling
LOOP_STEP(13); // Screen timeout
if (app_settings.screen_timeout > 0) { // 0 = never timeout