AMY-6M - Hardware Integration Manual
UBX-17021971 – R07
Design-in
Page 26 of 57
2.5.2
Configuration at runtime
Once the receiver has started, the Functional Configuration may be modified with UBX configuration messages.
The modified settings remain effective until power-down or reset. If these settings have been stored in non-
volatile memory as the EEPROM at DDC or the serial FLASH at SPI, the modified configuration will be retained. If
these settings have been stored in battery-backup RAM, then the modified configuration will be retained, as
long as the backup battery supply is not interrupted. See chapter “Receiver Configuration” in the
u-blox 6
Receiver Description including Protocol Specification
[2] for more information.
The configuration pins (CFG_COM0 and CFG_COM1) are shared with other functions (SPI interface pins MOSI
and MISO). During start-up, the module first reads the state of the configuration pins. Afterwards the other
functions can be used.
For more information about settings and messages see the
AMY-6M Data Sheet
2.6
RTC
The RTC crystal is optional as it is only required in stand-alone applications where hot or warm starts are
enabled. In these cases, actual time is maintained in the RTC and Ephemeris and other last known data is kept in
the backup RAM. In A-GPS based systems, the RTC is not required and coarse or fine time information is
available from the network. If neither backup RAM nor RTC are required, V_BCKP should be connected to GND.
The external circuit for normal RTC operation is shown in Figure 2.
If the RTC is not used, its input XTAL_IN should be connected to GND and the output XTAL_OUT must be left
open.
As an alternative to the RTC, a 32 kHz signal can be supplied from an external source (e.g. from the host system)
into XTAL_IN. This is a core domain signal; its high level must not exceed VDD_B (1.2V!). If the output buffer of
the RCT signal from host does exceed the VDD_B voltage, with a voltage divider (Rx and Ry) the voltage level can
be adjusted, see Figure 22. Minimum “high” level should be more than 0.8V.
Figure 22: RTC supplied by external source
RTC is highly recommended for Power Save Mode.
If AssistNow Autonomus is required, RTC is mandatory if the time at wakeup of receiver is not provided by
message (UBX-AID-INI). For more deatails see
u-blox 6 Receiver Description including Protocol Specification
