AMY-6M - Hardware Integration Manual
UBX-17021971 – R07
Design-in
Page 23 of 57
2.4
I/O Pins
2.4.1
Peripheral Input Output (PIO)
All PIOs have internal pull-ups or pull-downs (PIO9 only). Thus there is no need to connect PIOs to GND or VDD if
not used.
A signal change on pins RXD1, EXTINT0, or EXTINT1 can also be used to wake up the receiver from Sleep- or
Backup Mode.
2.4.1.1
PIO23
It is a requirement that pin PIO23 is connected to GND.
Always connect PIO23 to GND!
2.4.1.2
PIO21/SCK
Pin PIO21 is shared with the SPI clock pin SCK. PIO21 must be connected to GND if the SPI interface is not used.
To use the SPI interface PIO21 must be pulled to a low level during startup. This can be done with a 10k Ohm
pull down resistor to GND, see Figure 16. PIO21 must not be left open.
If SPI isn’t used, connect PIO21/SCK to GND.
2.4.1.3
TX Ready (ROM7.03 and above)
The TX ready signal indicates that the receiver has data to transmit. A listener can wait on the TX ready signal
instead of polling the DDC or SPI interfaces. The UBX-CFG-PRT message lets you configure the polarity and the
number of bytes in the buffer before the TX ready signal goes active. The TX ready signal can be mapped to
GPIO 05 (TXD1). The TX ready pin is disabled by default.
Most u-blox wireless modules configure and enable the TX ready functionality automatically at GPIO 05
(TXD1) of AMY-6M. See datasheet of the wireless module.
For more information on configuration and remap of this pin see the
AMY-6M Data Sheet
[1] and see also the
u-blox 6 Receiver Description including Protocol Specification
2.4.2
SAFEBOOT_N
Design a test point to access SAFEBOOT_N in the PCB design. If SAFEBOOT_N is low at start-up, the receiver
starts in a Safe Boot Mode and the GPS navigation engine is not started. This mode can be used for production
test.
Safe Boot Mode can be used to force the system into a known state regardless of any configuration pins or
contents of non-volatile memories. This can be used to recover from a situation where a non-volatile memory
was programmed with wrong settings. Since in Safe Boot Mode only a limited number of configurations are
available the same restriction may apply as mentioned before with regards to un-programmed non-volatile
memory, i.e. baud rates may be wrong or USB may not be functional.
Have at least one test-point available that allows setting pin SAFEBOOT_N to GND. This recommendation
should always be followed if external non-volatile memory is used in the application.