62
ATmega8515(L)
2512A–AVR–04/02
The following subsectionsshortly describethealternate functionsfor each port, and
relate theoverriding signals to thealternate function. Refer to thealternate function
description forfurtherdetails.
Special Function IO Register –
SFIOR
• Bit 2 – PUD: Pull-up Disable
When thisbit iswrittentoone, the pull-ups in the I/Oports are disabled even if the DDxn
and PORTxnRegisters are configured to enablethe pull-ups ({DDxn, PORTxn}=0b01).
See “Configuring thePin”onpage 57for more details about thisfeature.
Table 25. GenericDescription ofOverriding Signals for Alternate Functions.
Signal Name Full Name Description
PUOE Pull-upOverride
Enable
If thissignal isset, the pull-up enableiscontrolledbythe
PUOV signal. If thissignal iscleared, the pull-up is
enabledwhen {DDxn, PORTxn, PUD} = 0b010.
PUOVPull-upOverride
Value
If PUOE isset, the pull-up is enabled/disabledwhen
PUOVisset/cleared, regardless of the setting of the
DDxn, PORTxn, and PUD Registerbits.
DDOE Data Direction
Override Enable
If thissignal isset, the Output DriverEnableiscontrolled
by the DDOV signal. If thissignal iscleared, the Output
driver is enabledbythe DDxn Registerbit.
DDOV Data Direction
OverrideValue
If DDOE isset, the Output Driver is enabled/disabled
when DDOVisset/cleared, regardless of the setting of the
DDxn Registerbit.
PVOE PortValue
Override Enable
If thissignal isset and the Output Driver is enabled, the
portvalue iscontrolledbythePVOV signal. If PVOE is
cleared, and the Output Driver is enabled, the portValue is
controlledbythePORTxnRegisterbit.
PVOVPortValue
OverrideValue
If PVOE isset, the portvalue isset to PVOV,regardless of
the setting of thePORTxnRegisterbit.
DIEOE DigitalInput
Enable Override
Enable
If thisbit isset, the DigitalInput Enableiscontrolledbythe
DIEOV signal. If thissignal iscleared, the DigitalInput
Enableisdetermined by MCU-state (Normal mode,sleep
modes).
DIEOV DigitalInput
Enable Override
Value
If DIEOE isset, the DigitalInput is enabled/disabledwhen
DIEOVisset/cleared, regardless of the MCU state
(Normal mode,sleep modes).
DI DigitalInput This is the DigitalInput to alternate functions. Inthe figure,
the signal isconnected to theoutput of the schmitt trigger
but beforethe synchronizer. Unless the DigitalInput is
used as a clock source, themodule with thealternate
function will useits own synchronizer.
AIO Analog
Input/output
This is theAnalog Input/Output to/from alternate functions.
The signal isconnecteddirectly to the pad, andcan be
usedbi-directionally.
Bit 76543 210
– XMBK XMM2 XMM1 XMM0 PUD – PSR10 SFIOR
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
(151 stránky)
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