ZEUS Technical Manual

Detailed hardware description

 

 

Serial COM ports

There are seven serial communications ports available on the ZEUS. Three are provided by the PXA270 and are used for the optional wireless modem, GPS and IEEE802.15.4 / ZigBee ports.

There are four additional high-speed, 16550 compatible serial UARTs implemented by an EXAR ST16C554Q Quad UART device. Two of these channels (COM1, COM2) can be used as standard RS232 serial interfaces, COM3 can be configured as RS232 or RS485/422, and COM4 can be configured as RS422 or RS485. The table below provides a summary of the four additional serial ports.

Port

Address

IRQ

FIFO depth

Signals
RX / TX

COM1

0x10000000 –

GPIO9

16/16

RS232: Rx, Tx, CTS, RTS, RI,

 

0x1000000F

 

 

DSR, DCD, DTR

COM2

0x10800000 –

GPIO10

16/16

RS232: Rx, Tx, CTS, RTS, RI,

 

0x1080000F

 

 

DSR, DCD, DTR

COM3

0x11000000 –

GPIO12

16/16

RS232: Rx, Tx, CTS, RTS, RI,

 

0x1100000F

 

 

DSR, DCD, DTR

 

 

 

 

or

 

 

 

 

RS422/485: Rx, Tx

COM4

0x11800010 –

GPIO11

16/16

RS422/RS485: Rx, Tx

 

0x1180001F

 

 

 

 

 

 

 

 

COM1/2 – RS232 interface

Supported on Channel A and B of the external Quad UART, the ports are buffered to RS232 levels with ±15kV ESD protection, and support full handshaking and modem control signals. The maximum baud rate is 921.6 Kbaud. COM1 and COM2 ports can be accessed using DB9 connectors J11 and J15, respectively. For pin assignment and connector details, see J11 – Serial port – COM1 on page 83 and J15 – Serial port – COM2 on page 86.

A factory fit option configures COM1 as TTL Level signals to interface to certain specialized modems. Please contact Eurotech Technical Support (see page 97) for details.

© 2007 Eurotech Ltd Issue D

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