Bus Powered USB2.0 Flash Media Controller
Datasheet
BUFFER
TYPE
NAME
SYMBOL
DESCRIPTION
Memory
MA[15:0]
O8
O8
O8
O8
These signals address memory locations within the
external memory.
Program Memory Write; active low
Address Bus
Memory Read
nMWR
nMRD
nMCE
Strobe
Memory Read
Strobe
Program Memory Read; active low
Memory Chip
Program Memory Chip Enable; active low. This signal is
asserted, when the device is not is SUSPEND mode.
Enable
Note: This signal is held in a logic ‘high’ state (inactive)
during nRESET assertion.
MISC
GPIO6,
GPIO6
/ROMEN
I/O8PU
This pin has an internal weak pullup resistor that can be
ROMEN and
RXD
enabled or disabled by the state of nRESET.
The pullup is enabled when nRESET is active.
The pullup is disabled, when the nRESET is inactive
(some clock cycles later, after the rising edge of
nRESET).
The state of this pin is latched internally on the rising
edge of nRESET to determine if internal or external
program memory is used.
The state latched is stored in ROMEN bit of GPIO_IN1
register. After the rising edge of nRESET, this pin may be
used as GPIO6 or RXD.
When pulled low via an external weak pulldown resistor,
an external program memory should be connected to the
memory data bus. The USB2224 uses this external bus
for program execution.
When this pin is left unconnected or pulled high by a
weak pullup resistor, the USB2224 uses the internal ROM
for program execution.
This pin’s function while operating from internal ROM is
shown in Table 6.3 - GPIO Usage.
General
GPIO1
GPIO2
GPIO3
I/O8
I/O8
I/O8
This pin may be used either as input, edge sensitive
Purpose I/O
interrupt input, or output.
This pin’s function while operating from internal ROM is
shown in Table 6.3 - GPIO Usage.
General
This pin may be used either as input, edge sensitive
Purpose I/O
interrupt input, or output.
This pin’s function while operating from internal ROM is
shown in Table 6.3 - GPIO Usage.
General
This pin may be used either as input, edge sensitive
Purpose I/O
interrupt input, or output.
This pin’s function while operating from internal ROM is
shown in Table 6.3 - GPIO Usage.
SMSC USB2224
Page 13
Revision 1.3 (09-21-04)
DATASHEET
SMSC [ SMSC CORPORATION ]
