Manual

86
AT90S/LS8535
1041H–11/01
Figure 60. Port C Schematic Diagram (Pins PC7)
Port D Port D is an 8-bit bi-directional I/O port with internal pull-up resistors.
Three I/O memory address locations are allocated for Port D, one each for the Data
Register – PORTD, $12($32), Data Direction Register – DDRD, $11($31) and the Port D
Input Pins – PIND, $10($30). The Port D Input Pins address is read-only, while the Data
Register and the Data Direction Register are read/write.
The Port D output buffers can sink 20 mA. As inputs, Port D pins that are externally
pulled low will source current if the pull-up resistors are activated. Some Port D pins
have alternate functions as shown in Table 33.
Table 33. Port D Pin Alternate Functions
Port Pin Alternate Function
PD0 RXD (UART Input line)
PD1 TXD (UART Output line)
PD2 INT0 (External interrupt 0 input)
PD3 INT1 (External interrupt 1 input)
PD4 OC1B (Timer/Counter1 output compareB match output)
PD5 OC1A (Timer/Counter1 output compareA match output)
PD6 ICP (Timer/Counter1 input capture pin)
PD7 OC2 (Timer/Counter2 output compare match output)