Ampro Corporation 5001692A Serial Ports (J3, J9, J13, J14)

Chapter 3 Hardware

CoreModule 420 Reference Manual 33

Serial Ports (J3, J9, J13, J14)

The Atlas CPU and Super I/O chips each contain the circuitry for two of the four serial ports. The Atlas

CPU provides serial port 1 (J3) and se r ial port 2 (J9) through the two independent 1 0-pin connectors.

The Super I/O chip provides serial ports 3 (J13) and 4 (J14. The serial ports support the following

features:

•Programmable word length, stop bits and parity

•16-bit programmable baud rate generator

•Interrupt generator

•Loop-back mode

•16-bit FIFOs for each port

•Ports 1 and 2 are supported by the STPC Atlas processor and are 15540 compatible

♦Serial 1 (J3, COM1) supports RS232/RS485 and has full modem operation

♦Serial 2 (J9, COM2) supports RS232/RS485 and has full modem operation

•Ports 3 and 4 are supported by the Super I/O Controller and are 16550 compatible

♦Serial 3 (J13, COM3) supports RS232 with full modem support

♦Serial 4 (J14, COM4) supports RS232 with full modem support

NOTE The RS232/RS485 mode for Serial Port 1 (COM1) and Serial Port 2

(COM2) are selected in BIOS Setup Utility. The RS485 terminations

for Serial Port 1 (COM1) and Serial Port 2 (COM2) are selected using

jumpers (JP1 and JP2) on the board instead of the BIOS Setup Utility.

However, the RS232 mode is the default selection for either

Serial Port 1 or 2 (COM1 or COM2).

To implement a two-wired RS485 mode with either Serial Port (1 or 2),

you must tie pins 3 (RX Data –) to 5 (TX Data –) and pins 4 (Tx Data

+) to 6 (Rx Data +) at Serial Port 1 or 2 (J3 or J9) for the two-wire

interface. Alternatively, you may short the equivalent pins on the DB9

connector attached to respective serial port, as shown in Figure 3-1.

987

CM420RS485jump

Figure 3-1. Serial 1 to RS485 Conversion

Table 3-12 provides the signals for the corresponding pins of the two independent serial interface ports

(Serial 1 & 2) and Table 3-13 provides the signals for the corresponding pins of two independent serial

interface headers (Serial 3 & 4).