Datasheet

Table Of Contents
NEO-M8U - Data Sheet
UBX-15015679 - R06 Configuration management Page 16 of 27
Product Information
3 Configuration management
Configuration settings can be modified with UBX configuration messages. The modified settings
remain effective until power-down or reset. Settings can also be saved in battery-backed RAM, Flash
or both using the UBX-CFG-CFG message. If settings have been stored in battery-backed RAM then
the modified configuration will be retained as long as the backup battery supply is not interrupted.
Settings stored in Flash memory will remain effective even after power-down and do not require
backup battery supply.
3.1 Interface Selection (D_SEL)
At startup Pin 2 (D_SEL) determines which data interfaces are used for communication. If D_SEL is
set high or left open, UART and DDC become available. If D_SEL is set low, i.e. connected to ground,
the NEO-M8U module can communicate to a host via SPI.
PIN # D_SEL=”1”
(left open)
D_SEL =”0”
(connected to GND)
20 UART TX SPI MISO
21 UART RX SPI MOSI
19 DDC SCL SPI CLK
18 DDC SDA SPI CS_N
Table 8: Data interface selection by D_SEL