I/O Pin Assignment and Pin Functions
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. |