Port Cm - NEC UPD703116 User Manual

14.3.10 Port CM

Port CM is a 5-bit I/O port in which input or output can be specified in 1-bit units.
7 6
PCM – –
Bit position Bit name
4 to 0 PCMn
(n = 4 to 0)
Besides functioning as a port, in control mode, this can operate as the wait insertion signal input, internal system
clock output, and bus hold control signal output.
(1) Operation in control mode
Port
Port CM PCM0
PCM1
PCM2
PCM3
PCM4
Note The WAIT and HLDRQ signals are set to control mode by default in ROMless mode 0, 1 or single-chip
mode 1. Be sure to fix these pins to the inactive level when not used. These pins function in control mode
until port mode is set using the port CM mode control register (PMCCM), so be sure to set these pins to
the inactive level before setting PMCCM.
(2) Setting in I/O mode and control mode
Port CM is set in I/O mode using the port CM mode register (PMCM). In control mode, it is set using the port
CM mode control register (PMCCM).
(a) Port CM mode register (PMCM)
This register can be read/written in 8-bit or 1-bit units.
7 6
PMCM 1 1
Bit position Bit name
4 to 0 PMCMn
(n = 4 to 0)
708
CHAPTER 14 PORT FUNCTIONS
5 4 3
– PCM4 PCM3
I/O port
Alternate Pin Name
Note
WAIT Wait insertion signal input
CLKOUT Internal system clock output
HLDAK Bus hold acknowledge signal output
Note
HLDRQ Bus hold request signal input
−
Fixed in port mode
5 4 3
1 PMCM4 PMCM3
Specifies input/output mode of PCMn pin.
0: Output mode (output buffer on)
1: Input mode (output buffer off)
User's Manual U14492EJ5V0UD
2 1 0
PCM2 PCM1 PCM0
Function
Remarks
2 1 0
PMCM2 PMCM1 PMCM0
Function
Address Initial value
FFFFF00CH Undefined
Block Type
D
J
J
D
E
Address Initial value
FFFFF02CH FFH