Chapter 3

Hardware

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 serial port 2 (J9) through the two independent 10-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.

 

 

1 2 3 4 5

Serial Ports (J3, J9)

Or

Standard DB9 Serial

 

 

 

(COM1 or COM2)

Port Connector (Female)

 

 

 

Side View

 

Rear View

7

8

9

 

 

6

Figure 3-1. Serial 1 to RS485 Conversion

CM420RS485jump

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).

CoreModule 420

Reference Manual

33

Page 39
Image 39
Ampro Corporation 5001692A manual Serial Ports J3, J9, J13, J14, Serial 1 to RS485 Conversion