Support Information
M9328MX21ADSE User’s Manual, Rev. A
Freescale Semiconductor
3-19
3.4.2
UART4 Connector
Connector P2 connects to the UART4 pins of the i.MX21 MCU. UART4 is the secondary functionality of
these pins. This male DB9 connector is configured for RS-232 DTE operation. Figure 3-6 shows pin
assignments and Table 3-6 provides signal descriptions for the connector.
Figure 3-6. Connector
P2
(UART4) DTE Pin Assignments
Table 3-6. Connector P2 (UART4) DTE Signal Descriptions
Pin Signal
Description
1
CD
CARRIER DETECT — RS-232 input signal, can be jumpered to SD2_D2 at J5 or ignored
2
RXD
RECEIVED DATA — RS-232 serial data input signal, connected to USBH1_TXDP when
UART4 is enable.
3
TXD
TRANSMITTED DATA — RS-232 serial data output signal, connected to USBH1_TXDM
when UART4 is enabled
4
DTR
DATA TERMINAL READY — RS-232 output signal, can be jumpered to SD2_D0 or forced
active positive at J3
5
GND GROUND
6
DSR
DATA SET READY — RS-232 input signal, can be jumpered to SD2_D1 at J4 or ignored,
active positive
7
RTS
READY TO SEND — RS-232 output signal, active positive, connected to USBH1_RXDM
when UART4 is enabled
8
CTS
CLEAR TO SEND — RS-232 input signal, active positive, connected to USBH1_RXDP
when UART4 is enabled
9
RI
RING INDICATOR — RS-232 input signal, active positive, can be jumpered to SD2_D3 at
J6 or ignored
5
TX
D
DT
R
DS
R
RT
S
CT
S
RI
P2
4
3
2
1
6
7
8
9
RX
D
CD
G
ND