Freescale Semiconductor M9328MX21ADSE User Manual
Support Information
M9328MX21ADSE User’s Manual, Rev. A
3-18
Freescale Semiconductor
3.4
UART/RS-232 Connectors
This section describes the DB9 RS-232 serial interface connectors on the ADS. Each serial interface is
controlled by a UART that is either inside the i.MX21 processor or part of an external device.
controlled by a UART that is either inside the i.MX21 processor or part of an external device.
3.4.1
UART1 Connector
Connector P1 connects to the UART1 pins of the i.MX21 MCU. UART1 is the primary functionality of
the pins. This female DB9 connector is configured for RS-232 DCE operation. Figure 3-5 shows pin
assignments and Table 3-5 provides signal descriptions for the connector.
the pins. This female DB9 connector is configured for RS-232 DCE operation. Figure 3-5 shows pin
assignments and Table 3-5 provides signal descriptions for the connector.
Figure 3-5. Connector P1 (UART1) DCE Pin Assignments
Table 3-5. Connector P1 (UART1) DCE Signal Descriptions
Pin(s) Signal
Description
1
CD
CARRIER DETECT — RS-232 output signal, pulled active positive
2
TXD
TRANSMITTED DATA — RS-232 serial data output signal
3
RXD RECEIVED DATA — RS-232 serial data input signal
4
DTR
DATA TERMINAL READY — RS-232 input signal, the logic level signal is available at TP8
5
GND GROUND
6
DSR DATA SET READY — RS-232 output signal, pulled active positive
7
RTS
READY TO SEND — RS-232 input signal, active positive
8
CTS
CLEAR TO SEND — RS-232 output signal, active positive
9
RI
RING INDICATOR — RS-232 output signal, forced inactive negative
1
RX
D
TX
D
RI
CT
S
RT
S
DS
R
P1
2
3
4
5
9
8
7
6
DT
R
G
ND
CD