CHAPTER 14 PORT FUNCTIONS
User’s Manual U14359EJ4V0UM
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14.3.14 Port CD
Port CD is a 4-bit I/O port that can be set to the input or output mode in 1-bit units.
7
6
5
4
3
2
1
0
Address
After reset
PCD
–
–
–
–
PCD3
PCD2
PCD1
PCD0
FFFFF00EH Undefined
Bit position
Bit name
Function
3 to 0
PCDn
(n = 3 to 0)
Port CD
I/O port
In addition to their function as port pins, the port CD pins operate as the clock enable signal output to SDRAM,
synchronous clock output, column address strobe signal output, row address strobe signal output, and byte enable
signal output to SDRAM upon byte access, in the control mode.
(1) Operation in control mode
Port
Alternate Function Pin Name
Remark
Block Type
PCD0
SDCKE
Clock enable signal output
PCD1
SDCLK
Synchronous clock output
J
PCD2
LBE/SDCAS
Byte enable signal output/
column address strobe signal output
Port CD
PCD3
UBE/SDRAS
Byte enable signal output/
row address strobe signal output
K
(2) I/O mode/control mode setting
The port CD I/O mode setting is performed by the port CD mode register (PMCD), and the control mode
setting is performed by the port CD mode control register (PMCCD) and the port CD function control register
(PFCCD).
(a) Port CD mode register (PMCD)
This register can be read/written in 8-bit or 1-bit units.
7
6
5
4
3
2
1
0
Address
After reset
PMCD
1
1
1
1
PMCD3
PMCD2
PMCD1
PMCD0
FFFFF02EH
FFH
Bit position
Bit name
Function
3 to 0
PMCDn
(n = 3 to 0)
Port Mode
Specifies input/output mode for PCDn pin.
0: Output mode (output buffer on)
1: Input mode (output buffer off)
