Rainbow Electronics ATmega8515L - Manual (Page 62)

62
ATmega8515(L)
2512A–AVR–04/02
The following subsections shortly describe the alternate functions for each port, and
relate the overriding signals to the alternate function. Refer to the alternate function
description for further details.
Special Function IO Register –
SFIOR
• Bit 2 – PUD: Pull-up Disable
When this bit is written to one, the pull-ups in the I/O ports are disabled even if the DDxn
and PORTxn Registers are configured to enable the pull-ups ({DDxn, PORTxn} = 0b01).
See “Configuring the Pin” on page 57 for more details about this feature.
Table 25. Generic Description of Overriding Signals for Alternate Functions.
Signal Name Full Name Description
PUOE Pull-up Override
Enable If this signal is set, the pull-up enable is controlled by the
PUOV signal. If this signal is cleared, the pull-up is
enabled when {DDxn, PORTxn, PUD} = 0b010.
PUOV Pull-up Override
Value If PUOE is set, the pull-up is enabled/disabled when
PUOV is set/cleared, regardless of the setting of the
DDxn, PORTxn, and PUD Register bits.
DDOE Data Direction
Override Enable If this signal is set, the Output Driver Enable is controlled
by the DDOV signal. If this signal is cleared, the Output
driver is enabled by the DDxn Register bit.
DDOV Data Direction
Override Value If DDOE is set, the Output Driver is enabled/disabled
when DDOV is set/cleared, regardless of the setting of the
DDxn Register bit.
PVOE Port Value
Override Enable If this signal is set and the Output Driver is enabled, the
port value is controlled by the PVOV signal. If PVOE is
cleared, and the Output Driver is enabled, the port Value is
controlled by the PORTxn Register bit.
PVOV Port Value
Override Value If PVOE is set, the port value is set to PVOV, regardless of
the setting of the PORTxn Register bit.
DIEOE Digital Input
Enable Override
Enable If this bit is set, the Digital Input Enable is controlled by the
DIEOV signal. If this signal is cleared, the Digital Input
Enable is determined by MCU-state (Normal mode, sleep
modes).
DIEOV Digital Input
Enable Override
Value If DIEOE is set, the Digital Input is enabled/disabled when
DIEOV is set/cleared, regardless of the MCU state
(Normal mode, sleep modes).
DI Digital Input This is the Digital Input to alternate functions. In the figure,
the signal is connected to the output of the schmitt trigger
but before the synchronizer. Unless the Digital Input is
used as a clock source, the module with the alternate
function will use its own synchronizer.
AIO Analog
Input/output This is the Analog Input/Output to/from alternate functions.
The signal is connected directly to the pad, and can be
used bi-directionally.
Bit 7 6 5 4 3 2 1 0
– 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