CHAPTER 14 PORT FUNCTIONS
User’s Manual U14359EJ4V0UM
496
14.3.13 Port CM
Port CM is a 6-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
PCM
–
–
PCM5
PCM4
PCM3
PCM2
PCM1
PCM0
FFFFF00CH Undefined
Bit position
Bit name
Function
5 to 0
PCMn
(n = 5 to 0)
Port CM
I/O port
In addition to their function as port pins, in the control mode, the port CM pins operate as the wait insertion signal
input, internal system clock output/bus clock output, bus hold control signal output, and refresh request signal output
from DRAM.
(1) Operation in control mode
Port
Alternate Function Pin Name
Remark
Block Type
PCM0
WAIT
Wait insertion signal input
D
PCM1
CLKOUT/BUSCLK
Internal system clock output/bus
clock output
K
PCM2
HLDAK
Bus hold acknowledge signal
output
J
PCM3
HLDRQ
Bus hold request signal input
D
PCM4
REFRQ
Refresh request signal output
J
Port CM
PCM5
SELFREF
Self-refresh request signal input
E
(2) I/O mode/control mode setting
The port CM I/O mode setting is performed by the port CM mode register (PMCM), and the control mode
setting is performed by the port CM mode control register (PMCCM) and the port CM function control register
(PFCCM).
(a) Port CM mode register (PMCM)
This register can be read/written in 8-bit or 1-bit units.
7
6
5
4
3
2
1
0
Address
After reset
PMCM
1
1
PMCM5
PMCM4
PMCM3
PMCM2
PMCM1
PMCM0 FFFFF02CH
FFH
Bit position
Bit name
Function
5 to 0
PMCMn
(n = 5 to 0)
Port Mode
Specifies input/output mode for PCMn pin.
0: Output mode (output buffer on)
1: Input mode (output buffer off)