CHAPTER 2 PIN FUNCTIONS
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User’s Manual U14492EJ3V0UD
(8) PCS0 to PCS7 (Port CS) … I/O
Port CS is an 8-bit I/O port in which input or output can be set in 1-bit units.
Besides functioning as a port, in control mode, these operate as chip select signal output for when memory is
expanded externally.
An operation mode of port or control can be selected for each bit and specified by the port CS mode control
register (PMCCS).
(a) Port mode
PCS0 to PCS7 can be set to input or output in 1-bit units using the port CS mode register (PMCS).
(b) Control mode
PCS0 to PCS7 can be set to port or control mode in 1-bit units using PMCCS.
(i)
CS0 to CS7 (Chip select) … Output
This is the chip select signal for external SRAM, external ROM, or external peripheral I/O.
The signal CSn is assigned to memory block n (n = 0 to 7).
This is active for the period during which a bus cycle that accesses the corresponding memory block
is activated.
It is inactive in an idle state (TI).
(9) PDH0 to PDH7 (Port DH) … I/O
Port DH is an 8-bit I/O port in which input or output can be set in 1-bit units.
Besides functioning as a port, in control mode (external expansion mode), these operate as the address bus
(A16 to A23) for when memory is expanded externally.
An operation mode of port or control mode can be selected for each bit and specified by the port DH mode
control register (PMCDH).
(a) Port mode
PDH0 to PDH7 can be set to input or output in 1-bit units using the port DH mode register (PMDH).
(b) Control mode
PDH0 to PDH7 can be used as A16 to A23 by using PMCDH.
(i)
A16 to A23 (Address) … Output
This pin outputs the upper 8-bit address of the 24-bit address in the address bus on an external
access.
