
CHAPTER 2 PIN FUNCTIONS
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Preliminary User’s Manual U16031EJ2V1UD
(9)
PCD0 to PCD3 (Port CD) 3-state I/O
PCD0 to PCD3 function as a 4-bit I/O port that can be set to input or output in 1-bit units.
Besides functioning as a port, in control mode, these pins operate as control signal outputs for when the
memory and peripheral I/O are expanded externally.
The operation mode can be set to port or control mode in 1-bit units, specified by the port CD mode control
register (PMCCD).
(a) Port mode
PCD0 to PCD3 can be set to input or output in 1-bit units using the port CD mode register (PMCD).
(b) Control mode
PCD0 to PCD3 can be set to port or control mode in 1-bit units using the PMCCD register.
(i)
SDCKE (SDRAM clock enable) output
This is the SDRAM clock enable output signal. It becomes inactive in self-refresh and standby
mode.
(ii) BUSCLK (Clock output) output
This is a clock output pin for SDRAM.
(iii) SDCAS (SDRAM column address strobe) 3-state output
This is a command output signal for SDRAM.
(iv) SDRAS (SDRAM row address strobe) 3-state output
This is a command output signal for SDRAM.
(10) PAH0 to PAH9 (Port AH) 3-state I/O
PAH0 to PAH9 function as an 8- or 10-bit I/O port that can be set to input or output in 1-bit units.
Besides functioning as a port, in control mode, these pins operate as an address bus (A16 to A25) for when
the memory is expanded externally.
The operation mode can be set to port or control mode in 1-bit units, specified by the port AH mode control
register (PMCAH).
(a) Port mode
PAH0 to PAH9 can be set to input or output in 1-bit units using the port AH mode register (PMAH).
(b) Control mode
PAH0 to PAH9 can be set to function alternately as A16 to A25 using the PMCAH register.
(i)
A16 to A25 (Address) 3-state output
These are the address output pins of the higher 10 bits of the address bus’s 26-bit address when
the external memory is accessed.
The output changes in synchronization with the fall of the BUSCLK signal in the T1 state. In the idle
state (TI), the address of the bus cycle immediately before is retained.