I/O Pin Assignment and Pin Functions

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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.

 

EM203A_pin_assignment

Main connector

#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

#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.