NXP Semiconductors LPCXpresso54S018M, Руководство пользователя, Страница: 21 / 34

NXP Semiconductors
UM11192
User Manual for LPCXpresso54S018M Development Board
UM11192 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2019. All rights reserved.
User manual Rev. 1.0
— 13th February 2019
21 of 34
7.1.4 Shield board current measurement
To use the on-board current measurement circuitry, any expansion board must match the
functionality of the LPCXpresso54S018M. Refer to the board schematics for more
information.
8. Board peripheral connections
8.1 LPC54S018J4M USART ports and VCOM support
The LPCXpresso54S018M board provides access to USART connections from
Flexcomm4 at the expansion connector J13.
On LPCXpresso54S018M boards the USART from Flexcomm0 supports ISP UART
mode booting and is used by default for semi-hosting debug messages. This USART is
connected to a serial port on the Link2 Debug Probe, which provides a bridging function
to USB to a virtual com port (or “VCOM” port) on a host computer connected to the
debug link connector, J8. On revision C boards TXD and RXD from this USART are also
available at header P4, for an external serial connection to be made. When using the P4
connector, JP6 must be installed; note that when JP6 is installed the VCOM port
functionality is disabled.
The factory default CMSIS-DAP Link2 image includes UART bridge functionality (VCOM
support), and this firmware is also available with the LPCScrypt utility, available at
http://www.nxp.com/lpcutilities . The J-Link firmware image available from LPCScrypt
(version 1.9 onwards) or directly from SEGGER also has this feature (also see Section
5.3.)
8.1.1 P3 USART header
The P4 header is designed to be used with an external serial to USB or other 3.3V serial
device. P4 is only present on Revision C (and later) boards.
Table 3 shows the pin out
information. below. Note that the connections at P4 are made directly to the
LPC54S018J4M device, so care should be taken to avoid ESD discharge and voltages
outside the ratings of the device I/O pins.
Table 3. P4 connections
Pin Function
1 Ground
2 RXD (from LPC54S018J4M)
3 TXD (from LPC54S018J4M)
8.2 USB ports
The LPCXpresso54S018M incorporates connectors for the two USB ports of the
LPC54S018J4M device
– a full speed (USB0) and a high speed port (USB1). Both of
these USB ports support device and host functionality, but only one can be used as a
host port at any given time. Jumper settings must be set appropriately for host mode
selection, as described in this section.