Datasheet

67
ATmega329/3210/649/6410
2552I–AVR–04/07
MCUCR – MCU Control
Register
• Bit 4 – 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 60 for more details about this feature.
Alternate Functions of Port A The Port A has an alternate function as COM0:3 and SEG0:3 for the LCD Controller.
Table 28 and Table 29 relates the alternate functions of Port A to the overriding signals
shown in Figure 27 on page 65.
Bit 7 6 5 4 3 2 1 0
0x35 (0x55)
JTD – –PUD– – IVSEL IVCE MCUCR
Read/Write R/W R R R/W R R R/W R/W
Initial Value 0 0 0 0 0 0 0 0
Table 27. Port A Pins Alternate Functions
Port Pin Alternate Function
PA7 SEG (LCD Front Plane 3)
PA6 SEG (LCD Front Plane 2)
PA5 SEG (LCD Front Plane 1)
PA4 SEG (LCD Front Plane 0)
PA3 COM (LCD Back Plane 3)
PA2 COM (LCD Back Plane 2)
PA1 COM (LCD Back Plane 1)
PA0 COM (LCD Back Plane 0)
Table 28. Overriding Signals for Alternate Functions in PA7..PA4
Signal
Name PA7/SEG3 PA6/SEG2 PA5/SEG1 PA4/SEG0
PUOE LCDEN LCDEN LCDEN LCDEN
PUOV0000
DDOE LCDEN LCDEN LCDEN LCDEN
DDOV 0 0 0 0
PVOE0000
PVOV0000
PTOE––––
DIEOE LCDEN LCDEN LCDEN LCDEN
DIEOV0000
DI––––
AIO LCDSEG LCDSEG LCDSEG LCDSEG