Chapter 3
Hardware
CoreModule 720
Reference Manual
23
Serial Interfaces
The CoreModule 720 provides four RS-232 serial ports. The PCH EG20T contains the circuitry for all four
serial ports and delivers the signals through two RS-232 transceivers: one transceiver for port COM0 and the
second transceiver for ports COM1, COM2, and COM3. The serial ports support the following features:
•
One individual high-speed NS16C550A-compatible UART (COM0)
•
Programmable word length, stop bits, and parity
•
16-bit programmable baud rate generator and Interrupt generator
•
Loop-back mode
•
Four individual 16-bit FIFOs
•
Serial Port Headers
♦
J10 - Serial 1 (COM0) supports RS-232 and full modem
♦
J11 - Serial 2 (COM1, COM2, and COM3) supports RS-232
Table 3-4
defines the pins and corresponding signals for serial 1 header (J10), which each consist of 10 pins,
2 rows, odd/even sequence (1, 2), and 0.079" (2mm) pitch.
Note:
The shaded table cell denotes ground.
Table 3-4. Serial 1 (COM0) Interface Pin Signal Descriptions (J10)
Pin # Signal
DB9
Pin #
Description
1
S0_DCD* 1
COM0 Data Carrier Detect – Indicates external serial device is detecting
a carrier signal (i.e., a communication channel is currently open). In
direct connect environments, this input is driven by DTR as part of the
DTR/DSR handshake.
2
S0_DSR*
6
COM0 Data Set Ready – Indicates external serial device is powered,
initialized, and ready. Used as hardware handshake with DTR for overall
readiness.
3
S0_RXD
2
COM0 Receive Data – Serial port receive data input is typically held at a
logic 1 (mark) when no data is being transmitted, and is held “Off” for a
brief interval after an “On” to “Off” transition on the RTS line to allow
the transmission to complete.
4
S0_RTS*
7
COM0 Request To Send – Indicates serial port is ready to transmit data.
Used as hardware handshake with CTS for low level flow control.
5
S0_TXD
3
COM0 Transmit Data – Serial port transmit data output is typically held
to a logic 1 when no data is being sent. Typically, a logic 0 (On) must be
present on RTS, CTS, DSR, and DTR before data can be transmitted on
this line.
6
S0_CTS*
8
COM0 Clear To Send – Indicates external serial device is ready to
receive data. Used as hardware handshake with RTS for low level flow
control.
7
S0_DTR*
4
COM0 Data Terminal Ready – Indicates serial port is powered,
initialized, and ready. Used as hardware handshake with DSR for overall
readiness.
8
S0_RI*
9
COM0 Ring Indicator – Indicates external serial device is detecting a
ring condition. Used by software to initiate operations to answer and
open the communications channel.
9
GND
5
Ground
10
Key/NC
NC
Key Pin/Not connected
