CHAPTER 1 INTRODUCTION
User’s Manual U14272EJ3V0UM
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1.3.12 Clocked serial interface (CSI)
The V
R
4181 provides a clocked serial interface (CSI) which has an option to be configured as general-purpose I/O
pins. This interface supports slave mode operation only. The clocked serial interface requires allocation of 4 signals;
SI, SO, SCK, and FRM. The clock source for this interface is input on the pin assigned to SCK.
1.3.13 Keyboard interface (KIU)
The V
R
4181 provides support for an 8 x 8 key matrix. This keyboard interface can only be supported when the
CompactFlash interface is disabled and reconfigured to provide the SCANIN(7:0) inputs and the SCANOUT(7:0)
outputs.
1.3.14 General-purpose I/O
The V
R
4181 provides total 32 bits of general-purpose I/O. Sixteen of these, GPIO(31:16), are available through
pins allocated to other functions as shown in the following table. The DCD1#/GPIO29 is the only one of the 16 pins
that can cause the system’s waking up from a low power mode if enabled by software. The other pins have no
functions other than those listed below.
The remaining 16 bits of general-purpose I/O, GPIO(15:0), are allocated to pins by default. Each of these pins can
be configured to support a particular interface such as CSI, secondary serial interface (RS-232-C), programmable
chip selects, or color LCD control. Otherwise, each of these pins can be also defined as one of the following:
•
General-purpose input
•
General-purpose output
•
Interrupt request input
•
Wake-up input
Table 1-3. GPIO(31:0) Pin Functions
Pin designation
Alternate function
Pin designation
Alternate function
GPIO0
SI
GPIO16
IORD#
GPIO1
SO
GPIO17
IOWR#
GPIO2
SCK
GPIO18
IORDY
GPIO3
PCS0#
GPIO19
IOCS16#
GPIO4
−
GPIO20
Note
M/UBE#
GPIO5
DCD2#
GPIO21
RESET#
GPIO6
RTS2#
GPIO22
ROMCS0#
GPIO7
DTR2#
GPIO23
ROMCS1#
GPIO8
DSR2#
GPIO24
ROMCS2#
GPIO9
CTS2#
GPIO25
RxD1
GPIO10
FRM/SYSCLK
GPIO26
TxD1
GPIO11
PCS1#
GPIO27
RTS1#
GPIO12
FPD4
GPIO28
CTS1#
GPIO13
FPD5
GPIO29
DCD1#
GPIO14
FPD6/CD1#
GPIO30
DTR1#
GPIO15
FPD7/CD2#
GPIO31
DSR1#
Note This signal supports input only.