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Eurotech Appliances PXA270 COM3 – RS232/RS485/RS422 interface, U3_RS232EN, U3_RS422EN, (EXP1_GPIO 0), U3_TERM# (EXP1_GPIO 2), Termination resistors (120Ω)

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ZEUS Technical Manual	Detailed hardware description

COM3 – RS232/RS485/RS422 interface

Supported on Channel C of the external Quad UART, COM3 port can be configured by software as RS232 or RS485/RS422.

The port is buffered to RS232 (or RS485/RS422) levels with ±15kV ESD protection. RS232 interface supports full handshaking and modem control signals. The maximum baud rate on this channel is 921.6 Kbaud. COM3 RS232 interface is connected to the connector J19, and RS485/422 interface is connected to the connector J18. For pin assignment and connector details, see J18 – Serial port (RS485/422) – COM3 on page 87 and J19 – Serial ports – COM3/4 on page 88.

Three control outputs of I2C GPIO expander (I2C address 0x21) are used to select one of the operating modes RS232, RS485 or RS422. The selection is implemented by using two control signals (U3_RS232EN, U3_RS422EN) to enable/disable the associated transceivers. The control signal combinations are shown in the following table:

U3_RS232EN	U3_RS422EN
(EXP1_GPIO 0)	(EXP1_GPIO 1) Selected COM3 function
1	X	RS232
0	0	RS485 Full duplex
0	1	RS422 Half duplex

U3_RS232EN and U3_RS422EN are at logic ‘1’ upon reset.

The control signal U3_TERM# is used to enable/disable the RS485/422 line termination and must be enabled if the ZEUS board is at the end of the network. The following table shows the usage of U3_TERM# signal:

U3_TERM# (EXP1_GPIO 2)	Termination resistors (120Ω)
0	Connected
1	Disconnected

U3_TERM# is at logic ‘1’ upon reset.

The RS485/422 driver (LTC2859) on ZEUS features a logic-selectable reduced slew mode that softens the driver output edges to control the high frequency EMI emissions from equipment and data cables. The reduced slew rate mode is entered by taking the SLO# pin low, where the data rate is limited to about 250kbps. Slew limiting also mitigates the adverse effects of imperfect transmission line termination caused by stubs or mismatched cables.

U3_RS485_SLO# (EXP2_GPIO 5) Slew rate

0Reduced

1Normal

© 2007 Eurotech Ltd Issue D

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Contents

Technical Manual ZEUS Technical Manual Contents Page Product handling and environmental compliance Anti-statichandling Packaging Electromagnetic compatibility (EMC) RoHS compliance Introduction ZEUS-M64-F32-003-R6 ZEUS-M128-F32-004-I-R6 ZEUS-Mx-Fy-zzz-R6 ZEUS-Mx-Fy-zzz-I-R6 The ZEUS board is fully RoHS-6compliant Eurotech Sales ZEUS ‘at a glance’ 10-30Vinput option 5V input option ZEUS features Date/time support Audio and touchscreen I2C bus Configuration EPROM Watchdog timer Mechanical Environmental ZEUS support products About this manual Conventions Tables Byte lane Getting started Using the ZEUS Using the CompactFlash socket Using the serial interfaces (RS232/422/485) Using the audio features Using the Ethernet interface Using the PC/104 expansion bus Using the ZEUS Modem Modules Using the ZigBee Module Detailed hardware description ZEUS block diagram ZEUS address map UART and CPLD address map PXA270 processor Page PXA270 GPIO pin assignments Page Page source See section… Page Page Interrupt assignments Internal interrupts External interrupts On-BoardGPIO expanders pin assignments Expander 2 - I2C Address Real time clock Watchdog timer Watchdog Register [REG3] Memory Flash memory SDRAM Static RAM Configuration EEPROM Wireless support Wireless modem and GPS receiver Page IEEE802.15.4 / ZigBee module (ZMx) Expansion interfaces CPLD ver/issue register [REG0] SDIO CompactFlash CF reset register [REG2] PC/104 interface PC/104 interrupt register [REG1] Unsupported PC/104 interface features Flat panel display TFT panel data bit mapping to the ZEUS Page LCD logic and backlight power LCD backlight brightness control STN bias voltage LVDS interface LVDS_FES# (EXP2_GPIO1) Selected LVDS function Audio Touchscreen controller USB Ethernet Serial COM ports COM1/2 – RS232 interface COM3 – RS232/RS485/RS422 interface COM4 – RS422/485 interface RS422 RS485 Typical RS422 and RS485 connection CAN bus Split Termination CAN Transceiver I²C bus Quick Capture camera interface External General purpose I/O Temperature sensor JTAG and debug access Power and power management Power supplies DC input voltage (10-30V) 5V only operation On-boardsupplies Power management IC Battery backup Processor power management Page Peripheral devices power management Device Part number Condition Power (mW) CompactFlash power management Wireless modem power management USB power management Page CAN bus power management Clock generator power management COM Ports power management Temperature sensor power management I/O expander power management Configuration PROM power management Connectors, LEDs and jumpers Page Connectors Page Page Page Page Page Page J11 – Serial port – COM1 J12 & J13 – PC/104 connectors J14 – LCD connector J15 – Serial port – COM2 J16 – LVDS connector J17 – CAN bus J18 – Serial port (RS485/422) – COM3 J19 – Serial ports – COM3/4 J20 – CompactFlash connector J21 – IEEE802.15.4 / ZigBee connector J22 – SDIO socket J23 – Wireless modem/GPS module interface J24 – Backlight power (for flat panel displays) Jumpers JP1 – User jumpers JP2 – Battery disconnect JP3 – LCD logic supply selection JP4 – LVDS MSL selection JP5 & JP6 – CAN bus termination JP5 JP6 JP7 - JTAG Enable Status LEDs Flash LED User LEDs Appendix A - Contacting Eurotech Eurotech sales Eurotech technical support Eurotech Group Appendix B - Specification Page Appendix C - Mechanical diagram Page Appendix D - Reference information Product information EPIC information PC/104 Consortium USB information Intel Marvell www.marvell.com Exar Corporation Wolfson Microelectronics Appendix E - Wireless modem datasheets Sony Ericsson GR64 Page Siemens MC39i Page Fastrax iTrax03/08 Page Motorola iO270 Page Telit GE863-GPS Page Sierra Wireless MC8775 Page Sierra Wireless MC5720 Page Appendix F - ZEUS Modem details ZEUS Modem-1 ZEUS Modem-2 ZEUS Modem-3 J2 –Sierrawireless USB data connector ZEUS Modem connector details ZEUS host interface J9 –iO270audio/PTT connector Appendix G - ZEUS-FPIFdetails JP1 – TFT clock delay selection J1 – ZEUS LCD cable connector J2 – Generic LCD connector J3 – Direct connection to a NEC NL3224BC35-205.5inch 320x240 TFT display J4 – Backlight inverter connector J5 – STN Bias connector Appendix H - ZEUS-FPIF-CRTdetails J1 – ZEUS LCD cable connector J2 – CRT connector Appendix H - Acronyms and abbreviations Page Appendix I - RoHS-6Compliance - Materials Declaration Form Confirmation of Environmental Compatibility for Supplied Products Index