EVK-M8U User Guide
UBX-15023994 - R01
Advance Information
Device description
Page 10 of 26
3.3.7
Front test connector
This 14-pin connector provides access to additional functionality to the EVK via various interface pins. The
connector also enables measurement of the current used by the EVK. For accurate measurements, it is
recommended to use a cable of at most 1 meter in length.
When connecting the 3.3 V digital interfaces, SPI and DDC to your application, a cable length less than 25 cm is
recommended.
We recommend using the ACE-AM-0 mating connector or equivalent. The ACE-AM-0 is available on our Online
Shop https://shop-emea.u-blox.com/en/eur/3~330~EMEA/Evaluation-kits-tools/Accessories/Cables-books. All pins
are ESD protected.
PIN Nr.:
PIN NAME
I/O
LEVEL
DESCRIPTION
14
V5_IN
I
4.75 V – 5.25 V
Power input – can be used instead of USB
13
GND
I
-
Common ground pin for case-work, power and serial interface connections
12
P1A (VCC)
O
3.3 V
Regulated power output/monitor – max. current supply 100 mA
1
Ω
1% resistor for over-all current measurement to pin 11 (P1B)
NOTE: this supply powers the active antenna, additional LNA, LED and UART interface
buffers directly
11
P1B
O
Second connection for module current measurement (see Figure 10)
10
P2A
O
3.0 V
Battery output (unloaded)
100
Ω
1% resistor for battery backup current measurement to pin 9 (P2B)
NOTE: There is a current protection to 3 mA. See circuit in Figure 21 (D2, D4, R29)
9
P2B
O
Second junction for battery backup current measurement
8
RESERVED0
-
-
Not connected
7
EXTIN0
I
3.3 V
External interrupt input
6
RESERVED1
-
-
Not connected
5
SDA / CS
I/O
3.3 V
If slide switch on I2C, then DDC interface selected; Function: data input / output
If slide switch on SPI, then SPI interface selected; chip select input – LOW ACTIVE
4
SCL / SCK
I/O
3.3 V
Clock input / output
3
TxD / MISO
I/O
3.3 V
If slide switch on I2C, then DDC interface selected / UART TxD (3.3V Level)
If slide switch on SPI, then SPI interface selected; Master in Slave out (MISO)
2
RxD / MOSI
I/O
3.3 V
If slide switch on I2C, then DDC interface selected / UART RxD (3.3V Level)
If slide switch on SPI, then SPI interface selected; Master out Slave in (MOSI)
1
GND
I
-
Common ground pin
Table 4: Connector pin description for EVK-M8U (pins numbered from right to left on the front panel)
THE EVK CASE-WORK IS CONNECTED TO THE COMMON SUPPLY/INTERFACE GROUND PIN (PIN
13). Contact u-blox technical support for assistance if required.
3.3.8
LED
On the front panel of the unit, a single blue LED may be configured to follow the receiver time pulse signal using
message UBX-CFG-TP5. The time-pulse may be configured so that the LED starts flashing at one pulse per
second during a valid GNSS fix. If there is no GNSS fix, the LED will only light, without flashing. The time pulse is
enabled by default in EVK-M8U.
3.3.9
Backup battery
There is a backup battery in the unit. This is necessary to store calibration, dead-reckoning and orbital
information between operations to enable immediate start-up in DR mode and fast acquisition of GNSS signals.
It is a RENATA 3.0 V Li / MnO
2
battery of the type CR2450. The battery has a rated capacity of 540 mAh. The
battery operating temperature range is -40° C to +85° C.
