User manual

LPC4357 Developer’s Kit - User’s Guide

Page 27

4.15 SP9: UART Multiplexing

UART channels from four sources are multiplexed into one UART channel, which is connected to the

OEM Board:

 Serial Expansion Connector / RF module. Note that if the RF module is soldered to the board,

then UART channel on the Serial Expansion Connector is occupied.

 LCD Expansion connector

 RS422/485 Interface

 RS232 Interface

The multiplexing is static, in the sense that a change in the multiplexor setting requires jumpers to be

moved. It is not controlled from the OEM Board. The picture below shows where to find the pin list to

control multiplexing and the different settings. The table lists signal connection.

Jumper settings for JP6

UART to Serial Interface

Expansion Connector / RF-

module (default)

UART to LCD Expansion

Connector

UART to RS422/485

transceiver

UART to RS232 Interface

Figure 16 – UART Multiplexing

Signals

LPC4357

GPIO25_RXD

P2_4 via multiplexor, USART#3 is used

GPIO24_TXD

P9_3 via multiplexor, USART#3 is used

UART Multiplexing Control

JP6