Pin DescriptionsVCC Supply voltage GND Ground Port B (PB5..PB0) Port B is a 6-bit bi-directional I/O port with internal pullup resistors. The Port B output buffers can sink 20 mA. As inputs, Port B pins that are externally pulled low will source current if the pull-up resistors are activated. Port B also serves the functions of various special features of the AT90S2333/4433. The port B pins are tristated when a reset condition becomes active, even if the clock is not running. Port C (PC5..PC0) Port C is a 6-bit bi-directional I/O port with internal pullup resistors. The Port C output buffers can sink 20 mA. As inputs, Port C pins that are externally pulled low will source current if the pull-up resistors are activated. Port C also serves as the analog inputs to the A/D Converter. The port C pins are tristated when a reset condition becomes active, even if the clock is not running. Port D (PD7..PD0) Port D is an 8-bit bi-directional I/O port with internal pull-up resistors. 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. Port D also serves the functions of various special features of the AT90S2333/4433. The port D pins are tristated when a reset condition becomes active, even if the clock is not running. RESET Reset input. An external reset is generated by a low level on the RESET pin. Reset pulses longer than 50 ns will generate a reset, even if the clock is not running. Shorter pulses are not guaranteed to generate a reset. XTAL1 Input to the inverting oscillator amplifier and input to the internal clock operating circuit. XTAL2 Output from the inverting oscillator amplifier AVCC This is the supply voltage pin for the A/D Converter. It should be externally connected to V via a low-pass filter. See CC Datasheet for details on operation of the ADC. AREF This is the analog reference input for the A/D Converter. For ADC operations, a voltage in the range 2.7V to AVCC must be applied to this pin. AGND If the board has a separate analog ground plane, this pin should be connected to this ground plane. Otherwise, connect to GND. 4AT90S/LS2333 and AT90S/LS4433 Document Outline Features Description Block Diagram Pin Descriptions VCC GND Port B (PB5..PB0) Port C (PC5..PC0) Port D (PD7..PD0) RESET XTAL1 XTAL2 AVCC AREF AGND Architectural Overview Register Summary (Continued) Instruction Set Summary (Continued) Ordering Information Pin Configurations
