
III PERIPHERAL MODULES 1 (SYSTEM): MISC REGISTERS
S1C33E07 TECHNICAL MANUAL
EPSON
III-4-5
III
MISC
III.4.4 Pin Control Registers
III.4.4.1 Pull-up Control
The S1C33E07 input/output pins have a pull-up resistor that can be connected/disconnected to/from the pin by soft-
ware control, except some special pins. Each pin has a pull-up control bit to select whether the pull-up resistor is
used or not.
Table III.4.4.1.1 lists the correspondence between the register/control bits and pins.
Table III.4.4.1.1 Correspondence between Pull-up Control Bits and Pins
Pin
P07–P00
P17–P15
P14–P10
P27–P20
P36–P34
P33–P30
P47–P40
P57–P50
P67–P60
P74–P70
P85–P80
P97–P90
PA4–PA0
PB3–PB0
Control bit
PUP0[7:0] (D[7:0])
PUP1[7:5] (D[7:5])
PUP1[4:0] (D[4:0])
PUP2[7:0] (D[7:0])
PUP3[6:4] (D[6:4])
PUP3[3:0] (D[3:0])
PUP4[7:0] (D[7:0])
PUP5[7:0] (D[7:0])
PUP6[7:0] (D[7:0])
PUP7[4:0] (D[4:0])
PUP8[5:0] (D[5:0])
PUP9[7:0] (D[7:0])
PUPA[4:0] (D[4:0])
PUPB[3:0] (D[3:0])
Control register
P0 Pull-up Control Register (0x300C42)
P1 Pull-up Control Register (0x300C43)
P2 Pull-up Control Register (0x300C44)
P3 Pull-up Control Register (0x300C45)
P4 Pull-up Control Register (0x300C46)
P5 Pull-up Control Register (0x300C47)
P6 Pull-up Control Register (0x300C48)
P7 Pull-up Control Register (0x300C49)
P8 Pull-up Control Register (0x300C4A)
P9 Pull-up Control Register (0x300C4B)
PA Pull-up Control Register (0x300C4C)
PB Pull-up Control Register (0x300C4D)
Init.
No pull-up
Pull-up
No pull-up
Pull-up
No pull-up
Pull-up
No pull-up
Pull-up
When the pull-up control bit is set to 1, the corresponding pin will be pulled up in input mode. When not using
pull-up resistors, set the corresponding pull-up control bits to 0.
Notes: The pull-up control bit is effective in both cases when the pin is used for the external bus and
when used for the on-chip peripheral circuit or general-purpose I/O port.
When the port is in output mode, the port pin is not pulled up regardless of how the pull-up
control bit is set.
III.4.4.2 Driving Bus Signals Low
The S1C33E07 can drive the bus signal output pins forcibly low using a control register. This function is useful
when turning off the power of the external device connected to the bus.
Table III.4.4.2.1 lists the correspondence between the register/control bits and bus signals.
Table III.4.4.2.1 Correspondence between Low-Drive Control Bits and Bus Signals
Bus signal
D[15:0]
#CE[11:4]
A[24:0]
#RD, #WRL, #WRH, #BSL
Control bit
LDRVDB (D3)
LDRVCE (D2)
LDRVAD (D1)
LDRVRW (D0)
Control register
Bus Signal Low Drive
Control Register
(0x300C41)
When the control bit is set to 1, the corresponding bus signal goes low. When the control bit is set to 0, the signal
control goes back to the SRAMC/SDRAMC.
Notes: The low-drive control bit is disabled when the pin is used as the general-purpose I/O port (Pxx).
If the above signals are forcibly driven low when the CPU is running by the instructions fetched
from an external memory, the CPU will not be able to run after that point. To drive the signals
low, the CPU must be running with the program stored in the internal RAM.