
iiiPeriPheraLModuLes1(systeM):MisCregisters
s1C33L17teChniCaLManuaL
ePson
iii-4-5
III
MISC
iii.4.4PinControlregisters
iii.4.4.1Pull-upControl
The S1C33L17 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.
TableIII.4.4.1.1CorrespondencebetweenPull-upControlBitsandPins
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
Controlbit
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])
Controlregister
P0Pull-upControlRegister(0x300C42)
P1Pull-upControlRegister(0x300C43)
P2Pull-upControlRegister(0x300C44)
P3Pull-upControlRegister(0x300C45)
P4Pull-upControlRegister(0x300C46)
P5Pull-upControlRegister(0x300C47)
P6Pull-upControlRegister(0x300C48)
P7Pull-upControlRegister(0x300C49)
P8Pull-upControlRegister(0x300C4A)
P9Pull-upControlRegister(0x300C4B)
PAPull-upControlRegister(0x300C4C)
PBPull-upControlRegister(0x300C4D)
init.
Nopull-up
Pull-up
Nopull-up
Pull-up
Nopull-up
Pull-up
Nopull-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: Thepull-upcontrolbitiseffectiveinbothcaseswhenthepinisusedfortheexternalbusand
whenusedfortheon-chipperipheralcircuitorgeneral-purposeI/Oport.
Whentheportisinoutputmode,theportpinisnotpulledupregardlessofhowthepull-up
controlbitisset.
iii.4.4.2drivingBussignalsLow
The S1C33L17 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.
TableIII.4.4.2.1CorrespondencebetweenLow-DriveControlBitsandBusSignals
Bussignal
D[15:0]
#CE[11:4]
A[24:0]
#RD,#WRL,#WRH,#BSL
Controlbit
LDRVDB(D3)
LDRVCE(D2)
LDRVAD(D1)
LDRVRW(D0)
Controlregister
BusSignalLowDrive
ControlRegister
(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: Thelow-drivecontrolbitisdisabledwhenthepinisusedasthegeneral-purposeI/Oport(Pxx).
IftheabovesignalsareforciblydrivenlowwhentheCPUisrunningbytheinstructionsfetched
fromanexternalmemory,theCPUwillnotbeabletorunafterthatpoint.Todrivethesignals
low,theCPUmustberunningwiththeprogramstoredintheinternalRAM.