I/O Pin Assignment and Pin Functions

A warning note icon.This is a legacy product. The following is provided as it was documented originally, albeit with some corrections and changes for clarity and style.

The EM203A has two connectors -- main connector and magnetics connector. Depending on the EM203A version, magnetics connector can be soldered facing up or down, as described in the Mechanical Dimensions topic.

Pin Functions and Descriptions

Main Connector

Pin Number

Signal Name

Direction

Description

#1

MD*

Input

Mode selection pin

#2

RST

Input

Reset, active high

#3

P3

DTR*

Input/output

Output

General-purpose input/output line

Data terminal ready output

#4

P2

DSR*

Input/output

Input

General-purpose input/output line

Data set ready input

#5**

L3

SG*

Output

Output

LED output 3

Green status LED control line

#6**

L4

SR*

Output

Output

LED output 4

Red status LED control line

#7**

VCC

Positive power input, 5V nominal, +/- 5%, app. 220mA

#8**

GND

Ground

#9

RX

Input

Serial receive line

#10

TX

Output

Serial transmit line

#11

P4

CTS/SEL*

Input/output

Input

General-purpose input/output line

Clear to send input; full-/half-duplex selection input

#12

P5

RTS/DIR*

Input/output

Output

General-purpose input/output line

Request to send output (full-duplex mode); data direction control output (half-duplex mode)


* Implemented in (supported through) firmware.

** For the EM203A device (without "D" option), these pins also extend upward so that they can potentially mate with the RJ203A module.


Magnetics Connector

Pin Number

Signal Name

Direction

Description

#1

RX+

Input

Ethernet port, positive line of the differential input signal pair

#2

RX-

Input

Ethernet port, negative line of the differential input signal pair

#3

AVCC

Output

"Clean" 3.3V power output for magnetics circuitry

#4

TX+

Output

Ethernet port, positive line of the differential output signal pair

#5

TX-

Output

Ethernet port, negative line of the differential output signal pair

#6

L1(EG)

Output

Green Ethernet status LED control line.

#7

L2(EY)

Output

Yellow Ethernet status LED control line.

I/O Pin Assignment and Pin Functions

Pin Functions and Descriptions

Main Connector

Magnetics Connector