EVK-M91 - User guide
2.
SPI – In this selection the EVK operates only with the SPI interface. RS232 is switched off.
4.1.2 USB
The USB Type-C connector on the evaluation board can be used for both power supply and
communication. The easiest way to evaluate the EVK-M91 operation is to connect the EVK to a PC by
the USB-C 2.0 cable and then to use the u-center to configure and monitor the GNSS functions. The
USB connector has a direct connection to the u-blox M9 receiver, which enables the USB interface
to be used as a communication interface as well.
When the board is connected to the PC, Windows creates a virtual COM port to the PC. This
newly created virtual COM port needs then to be selected on the u-center application. The USB
communication speed is by default set to 38400 baud. EVK-M91 supports speeds up to 921600
baud.
4.1.3 UART
The evaluation unit includes two options for the UART connection, one is an RS232 port for serial
communication with the PC and the other one is the 14-pin connector.
4.1.3.1 RS232
Connect using a straight RS232 serial cable with male and female connectors to the port on your
PC. The maximum cable length is < 3.0 meters. To configure the RS232 port, use the CFG-VALSET
command and select CFG-UART1 Configuration group in the u-center application. The maximum
operating baud rate is 921600 Bd. If you are using a USB to RS232 adaptor cable, you can connect
it directly to the evaluation kit RS232 port.
The 9-pin RS232 female connector is assigned as listed below:
Pin Nr.
Assignment
1 & 6
Time pulse
2
TXD/SPI_MISO, GNSS Transmit Data, serial data to external
device
3
RXD/SPI_MOSI, GNSS Receive Data, serial data from
external device
4
EXTINT
5
GND
7, 8 & 9
not connected
Table 4: EVK-M91 RS232 connector pin description
4.1.3.2 14-pin connector
There is a 14-pin connector on the EVK-M91. It provides PIO, interfaces and supply options. All these
pins are ESD protected. The 14-pin connector can be used for interfacing with UART, SPI, I2C and
for evaluating other advanced scenarios.
Pin Nr.
Pin name
I/O
Level
Description
14
V5 IN
I
4.75-5.25 V
Power input – can be used instead of USB
13
GNSS I2
O
5.0 V
Supply current measurement (total current) node 2. See
description for pin 12.
12
GNSS I1
O
5.0 V
Supply current measurement (total current) node 1.
Connected to 5 V power supply. Current measured over a
1
Ω
1% resistor between pins 12 (GNSS I1) and 11 (GNSS
I2). Pin 12 (GNSS I1) is at higher potential. NOTE: the total
current includes also LNA and SPI flash.
UBX-19056858 - R02
4 Device description
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