diff --git a/RTC.cpp b/RTC.cpp
new file mode 100644
index 000000000..9053f5b2b
--- /dev/null
+++ b/RTC.cpp
@@ -0,0 +1,161 @@
+#include "RTC.h"
+#include "configuration.h"
+#include "main.h"
+#include <sys/time.h>
+#include <time.h>
+
+static RTCQuality currentQuality = RTCQualityNone;
+
+RTCQuality getRTCQuality()
+{
+    return currentQuality;
+}
+
+// stuff that really should be in in the instance instead...
+static uint32_t
+    timeStartMsec; // Once we have a GPS lock, this is where we hold the initial msec clock that corresponds to that time
+static uint64_t zeroOffsetSecs; // GPS based time in secs since 1970 - only updated once on initial lock
+
+void readFromRTC()
+{
+    struct timeval tv; /* btw settimeofday() is helpfull here too*/
+#ifdef RV3028_RTC
+    if(rtc_found == RV3028_RTC) {
+        uint32_t now = millis();
+        Melopero_RV3028 rtc;
+        rtc.initI2C();
+        tm t;
+        t.tm_year = rtc.getYear() - 1900;
+        t.tm_mon = rtc.getMonth() - 1;
+        t.tm_mday = rtc.getDate();
+        t.tm_hour = rtc.getHour();
+        t.tm_min = rtc.getMinute();
+        t.tm_sec = rtc.getSecond();
+        tv.tv_sec = mktime(&t);
+        tv.tv_usec = 0;
+        DEBUG_MSG("Read RTC time from RV3028 as %ld\n", tv.tv_sec);
+        timeStartMsec = now;
+        zeroOffsetSecs = tv.tv_sec;
+        if (currentQuality == RTCQualityNone) {
+            currentQuality = RTCQualityDevice;
+        }
+    }
+#elif defined(PCF8563_RTC)
+    if(rtc_found == PCF8563_RTC) {
+        uint32_t now = millis();
+        PCF8563_Class rtc;
+        rtc.begin();
+        auto tc = rtc.getDateTime();
+        tm t;
+        t.tm_year = tc.year - 1900;
+        t.tm_mon = tc.month - 1;
+        t.tm_mday = tc.day;
+        t.tm_hour = tc.hour;
+        t.tm_min = tc.minute;
+        t.tm_sec = tc.second;
+        tv.tv_sec = mktime(&t);
+        tv.tv_usec = 0;
+        DEBUG_MSG("Read RTC time from PCF8563 as %ld\n", tv.tv_sec);
+        timeStartMsec = now;
+        zeroOffsetSecs = tv.tv_sec;
+        if (currentQuality == RTCQualityNone) {
+            currentQuality = RTCQualityDevice;
+        }
+    }
+#else 
+    if (!gettimeofday(&tv, NULL)) {
+        uint32_t now = millis();
+        DEBUG_MSG("Read RTC time as %ld\n", tv.tv_sec);
+        timeStartMsec = now;
+        zeroOffsetSecs = tv.tv_sec;
+    }
+#endif
+}
+
+/// If we haven't yet set our RTC this boot, set it from a GPS derived time
+bool perhapsSetRTC(RTCQuality q, const struct timeval *tv)
+{
+    static uint32_t lastSetMsec = 0;
+    uint32_t now = millis();
+
+    bool shouldSet;
+    if (q > currentQuality) {
+        currentQuality = q;
+        shouldSet = true;
+        DEBUG_MSG("Upgrading time to RTC %ld secs (quality %d)\n", tv->tv_sec, q);
+    } else if(q == RTCQualityGPS && (now - lastSetMsec) > (12 * 60 * 60 * 1000UL)) {
+        // Every 12 hrs we will slam in a new GPS time, to correct for local RTC clock drift
+        shouldSet = true;
+        DEBUG_MSG("Reapplying external time to correct clock drift %ld secs\n", tv->tv_sec);
+    }
+    else
+        shouldSet = false;
+
+    if (shouldSet) {
+        lastSetMsec = now;
+
+        // This delta value works on all platforms
+        timeStartMsec = now;
+        zeroOffsetSecs = tv->tv_sec;
+
+        // If this platform has a setable RTC, set it
+#ifdef RV3028_RTC
+        if(rtc_found == RV3028_RTC) {
+            Melopero_RV3028 rtc;
+            rtc.initI2C();
+            tm *t = localtime(&tv->tv_sec);
+            rtc.setTime(t->tm_year + 1900, t->tm_mon + 1, t->tm_wday, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec);
+            DEBUG_MSG("RV3028_RTC setTime %02d-%02d-%02d %02d:%02d:%02d %ld\n", t->tm_year + 1900, t->tm_mon + 1, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec, tv->tv_sec);
+        }
+#elif defined(PCF8563_RTC)
+        if(rtc_found == PCF8563_RTC) {
+            PCF8563_Class rtc;
+            rtc.begin();
+            tm *t = localtime(&tv->tv_sec);
+            rtc.setDateTime(t->tm_year + 1900, t->tm_mon + 1, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec);
+            DEBUG_MSG("PCF8563_RTC setDateTime %02d-%02d-%02d %02d:%02d:%02d %ld\n", t->tm_year + 1900, t->tm_mon + 1, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec, tv->tv_sec);
+        }
+#elif defined(ARCH_ESP32)
+        settimeofday(tv, NULL);
+#endif
+
+        // nrf52 doesn't have a readable RTC (yet - software not written)
+#ifdef HAS_RTC
+        readFromRTC();
+#endif
+
+        return true;
+    } else {
+        return false;
+    }
+}
+
+bool perhapsSetRTC(RTCQuality q, struct tm &t)
+{
+    /* Convert to unix time
+    The Unix epoch (or Unix time or POSIX time or Unix timestamp) is the number of seconds that have elapsed since January 1, 1970
+    (midnight UTC/GMT), not counting leap seconds (in ISO 8601: 1970-01-01T00:00:00Z).
+    */
+    time_t res = mktime(&t);
+    struct timeval tv;
+    tv.tv_sec = res;
+    tv.tv_usec = 0; // time.centisecond() * (10 / 1000);
+
+    // DEBUG_MSG("Got time from GPS month=%d, year=%d, unixtime=%ld\n", t.tm_mon, t.tm_year, tv.tv_sec);
+    if (t.tm_year < 0 || t.tm_year >= 300) {
+        // DEBUG_MSG("Ignoring invalid GPS month=%d, year=%d, unixtime=%ld\n", t.tm_mon, t.tm_year, tv.tv_sec);
+        return false;
+    } else {
+        return perhapsSetRTC(q, &tv);
+    }
+}
+
+uint32_t getTime()
+{
+    return (((uint32_t) millis() - timeStartMsec) / 1000) + zeroOffsetSecs;
+}
+
+uint32_t getValidTime(RTCQuality minQuality)
+{
+    return (currentQuality >= minQuality) ? getTime() : 0;
+}