I/O Pin Assignment and Pin Functions

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The EM203 has two connectors -- main connector and magnetics connector. Depending on the EM203 version, magnetics connector can be soldered facing up or down, as described in the Mechanical Dimensions topic.

 

EM203_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.

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" 1.8V power output for magnetics circuitry

#4

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#5

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#6

GND

 

Ground

#7

TX+

Output

Ethernet port, positive line of the differential output signal pair

#8

TX-

Output

Ethernet port, negative line of the differential output signal pair