Port A - NEC V850E/MS1 UPD703100 User Manual

12.3.14 Port A

Port A is an 8-bit input/output port that can be set to input or output in 1-bit units.
7 6
PA PA7 PA6
Bit Position Bit Name
7 to 0 PAn (n = 7 to 0)
In addition to their function as port pins, the port A pins can also operate in the control mode (external expansion
mode) as an address bus used when memory is expanded externally.
(1) Operation in control mode
Port
Port A PA0 to PA7 A0 to A7
(2) Input/output mode/control mode setting
Port A input/output mode setting is performed by means of the port A mode register (PMA), and control mode
(external expansion mode) setting is performed by means of the mode specification pins (MODE0 to MODE3)
and the memory expansion mode register (MM: refer to 3.4.6 (1)).
(a) Port A mode register (PMA)
This register can be read/written in 8- or 1-bit units.
7 6
PMA PMA7 PMA6
Bit Position Bit Name
7 to 0 PMAn
(n = 7 to 0)
CHAPTER 12 PORT FUNCTIONS
5 4 3
PA5 PA4 PA3
Port A
Input/output port
Control Mode
Address bus in memory expansion
5 4 3
PMA5 PMA4 PMA3
Port Mode
Sets PAn pin in input/output mode.
0: Output mode (output buffer ON)
1: Input mode (output buffer OFF)
User's Manual U12688EJ4V0UM00
2 1 0
PA2 PA1 PA0
Function
Remark
2 1 0
PMA2 PMA1 PMA0
Function
Address After reset
FFFFF01CH Undefined
Block Type
F
Address After reset
FFFFF03CH FFH
403