Squeeze two floats into two uint16_t's

rtc_backup.c

void writeRtcLatLng(void)
{
    uint32_t tmp;

    // RTC Backup registers have the first 2 bytes reserved. So we get to use the second half of each.

    // Write lat tp first two backup registers
    tmp = *(uint32_t*)⪫
    rtcRegWrite(RTC_BKP_DR6, tmp >> 16);
    rtcRegWrite(RTC_BKP_DR7, tmp & 0xffff);

    // Read lon from third and fourth backup registers
    tmp = *(uint32_t*)&lng;
    rtcRegWrite(RTC_BKP_DR8, tmp >> 16);
    rtcRegWrite(RTC_BKP_DR9, tmp & 0xffff);

    printf("[readRtcLatLng] wrote to RTC backup registers lat: %f lng: %f\r\n", lat, lng);
}

void readRtcLatLng(void)
{
    uint32_t tmp;

    // RTC Backup registers have the first 2 bytes reserved. So we get to use the second half of each.

    // Read lat from first two backup registers
    tmp = rtcRegRead(RTC_BKP_DR6);
    tmp <<= 16;
    tmp |= rtcRegRead(RTC_BKP_DR7);
    lat = *(float*)&tmp;

    // Read lon from third and fourth backup registers
    tmp = rtcRegRead(RTC_BKP_DR8);
    tmp <<= 16;
    tmp |= rtcRegRead(RTC_BKP_DR9);
    lng = *(float*)&tmp;

    printf("[readRtcLatLng] read from RTC backup registers lat: %f lng: %f\r\n", lat, lng);
}