SMSC USB2242i User Manual

Ultra Fast USB 2.0 Memory Stick Flash Media Controller

Revision 1.0 (05-27-08)

10

SMSC USB2242/USB2242i

This section provides a detailed description of each signal. The signals are arranged in functional
groups according to their associated interface.

The “n” symbol in the signal name indicates that the active, or asserted, state occurs when the signal
is at a low voltage level. When “n” is not present before the signal name, the signal is asserted at the
high voltage level.

The terms assertion and negation are used exclusively. This is done to avoid confusion when working
with a mixture of “active low” and “active high” signals. The term assert, or assertion, indicates that a
signal is active, independent of whether that level is represented by a high or low voltage. The term
negate, or negation, indicates that a signal is inactive.

MS System Data 
In/Out

MS_D[7:0]

8
7
4
5

23
20
10

11

I/O12PD

These pins are the bi-directional data 
signals for the MS device.  In serial mode, 
the most significant bit (MSB) of each byte 
is transmitted first by either MSC or MS 
device on MS_D0.  MS_D0, MS_D2, and 
MS_D3 have weak pull-down resistors.  
MS_D1 has a pull down resistor if it is in 
parallel mode, otherwise it is disabled.  In 
4 or 8 bit parallel mode, there is a weak 
pull-down resistor on all MS_D7 - 0 
signals.  The resistors are controlled by 
MSC_SYSTEM_0, MSC_MODE_CTL and 
MSC_PRO_HG registers.

MS Bus State

MS_BS

9

O12

This pin is connected to the BS pin of the 
MS device. 

It is used to control the Bus States 0, 1, 2 
and 3 (BS0, BS1, BS2 and BS3) of the MS 
device.

MS System CLK

MS_SCLK

30

O12

This pin is an output clock signal to the 
MS device.

The clock frequency is software 
configurable.

MS Card Insertion 
GPIO

GPIO12
(MS_INS)

24

IPU

This is a GPIO designated as the Memory 
Stick

TM

 card detection pin.

USB Bus Data

USB+
USB-

2
3

I/O-U

These pins connect to the USB bus data 
signals.