Rainbow Electronics Atmega169L - Manual (Page 57)

57
ATmega169V/L
2514A–AVR–08/02
MCU Control Register –
MCUCR
• 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 51 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 27 and Table 28 relates the alternate functions of Port A to the overriding signals
shown in Figure 25 on page 55.
Bit 7 6 5 4 3 2 1 0
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 26. Port A Pins Alternate Functions
Port Pin Alternate Function
PA7 SEG3 (LCD Front Plane 3)
PA6 SEG2 (LCD Front Plane 2)
PA5 SEG1 (LCD Front Plane 1)
PA4 SEG0 (LCD Front Plane 0)
PA3 COM3 (LCD Back Plane 3)
PA2 COM2 (LCD Back Plane 2)
PA1 COM1 (LCD Back Plane 1)
PA0 COM0 (LCD Back Plane 0)
Table 27. Overriding Signals for Alternate Functions in PA7..PA4
Signal Name PA7/SEG3 PA6/SEG2 PA5/SEG1 PA4/SEG0
PUOE LCDEN LCDEN LCDEN LCDEN
PUOV 0 0 0 0
DDOE LCDEN LCDEN LCDEN LCDEN
DDOV 0 0 0 0
PVOE 0 0 0 0
PVOV 0 0 0 0
PTOE – – – –
DIEOE LCDEN LCDEN LCDEN LCDEN
DIEOV 0 0 0 0
DI – – – –
AIO SEG3 SEG2 SEG1 SEG0