PCM-2074 EVB User Manual
SMSC PCM-2074
USER MANUAL
Revision 1.0 (03-31-06)
7
4 I/O Connectors
The Main Board has two connectors - CN1 and CN2 - to allow for input/output signals. CN1 comes
mounted with a 14-pin connector, which is used to attach the RS485 Board using a ribbon cable. CN2,
which has no connector attached, can be used for an optional GPIO (General Input/Output) connector.
Note:
When using either connector, please adhere to the electrical limits specified in the TMC2074
datasheet.
below shows the pin-out for the CN1 connector on the Main Board. It also shows the pin-out
for the CN1 connector on the RS485 Board, except that all locations noted as Inputs change to Outputs
and all locations noted as Outputs change to Inputs.
The pin-out for CN2 on the Main Board is shown in
below.
Table 4.1 Pin Assignments for CN1
Pin No.
Attribute
Name
Pin No.
Attribute
Name
1
P
VDD (+5V)
1
2
P
VDD (+5V)
1
3
I
nCMIBYP
2
4
I
nHUBON
2
5
O
TXEN
2
6
P
GND
7
I
RXIN
2
8
P
GND
9
O
TXD
2
10
P
GND
11
I
RXIN2
2
12
P
GND
13
O
TXEN2
2
14
I
TXENPOL
2
Legend: P = Power/Ground; O = Output, I = Input, N/C - No Connection
Notes:
1) Allowable current is 200mA or less;
2) All Input and Output signals are buffered by a TC74VHCT244 and have 10k-ohm pull-up resistors
connected.
Table 4.2 Pin Assignments for CN2
Pin No.
Attribute
Name
Pin No.
Attribute
Name
1
P
VDD (+5V)
1
2
B
GPIO7
3
3
B
GPIO6
3
4
B
GPIO5
3
5
B
GPIO4
3
6
B
GPIO3
3
7
B
GPIO2
3
8
B
GPIO1
3
9
B
GPIO0
3
10
P
GND
11
I
nNSTCOUT
3
12
O
nRST
2
Legend: P = Power/Ground; O = Output, I = Input, B - Bi-directional
Notes:
1) Allowable current is 100mA or less;
2) nRST is an active-low, reset output signal, and is buffered by a TC74VHCT08.
3) GPIO(7:0) and nNSTCOUT connect directly to the TMC2074, with no additional buffering.
