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MPC5668EVB Users Manual Rev 0.1 May 2009
MPC5668EVBUM/D Page 16 of 29
The RS232 circuitry
is located at the top
edge of the EVB in
an area titled “SCI”
3.6 RS232 Configuration (J6, J17, J18, J23, J24)
The EVB has a single MAX3223 RS232 transceiver device, providing RS232 signal translation for the MCU
SCI channels A and B.
Each of the two RS232 outputs from the MAX232 device is connected to a DB9 connector, allowing a direct
RS232 connection to a PC or terminal. Connector P1A provides the RS232 level interface for MCU SCI-A and
P1B for MCU SCI-B. The pinout of these connectors is detailed below. Note that hardware flow control is not
supported on this implementation.
Figure 3-10 RS232 Physical Interface Connector
The MPC5668 eSCI also provides hardware LIN master capability which is supported on the EVB via LIN
transceivers. Jumpers J17, J18, J23 and J24 are provided to isolate the MCU SCI signals from the RS232
interface as described below. There is also a global power jumper (J9) controlling the power to the RS232
transceiver.
Table 3-15 RS232 Control Jumpers
Jumper Position PCB Legend Description
J6
(SCI-PWR)
FITTED (D) Power is applied to the MAX3223 transceiver
REMOVED No power is applied to the MAX3223 transceiver
J18 (SCI-A)
FITTED (D)
TXD
MCU TXD-A is routed to MAX3223
REMOVED MCU TXD-A signal is disconnected from CAN/LIN
J17 (SCI-A)
FITTED (D)
RXD
MCU RXD-A is routed via MAX3223
REMOVED MCU RXD-A signal is disconnected from CAN/LIN
J23 (SCI-B)
FITTED (D)
TXD
MCU TXD-B is routed via MAX3223
REMOVED MCU TXD-B signal is disconnected from CAN/LIN
J24 (SCI-B)
FITTED (D)
RXD
MCU RXD-B is routed via MAX3223
REMOVED MCU RXD-B signal is disconnected from CAN/LIN
The default configuration enables SCI-A and SCI-B channels. RS232 compliant interfaces (with no hardware
flow control) are available at DB9 connector P1. If the MCU is configured such that SCI-A or SCI-B is set as a
normal I/O port, then the relevant jumpers must be removed to avoid any conflicts occurring. If required,
jumper J6 can be used to completely disable the SCI transceiver.