AT90S/LS2333 and AT90S/LS4433

4

Pin Descriptions

VCC

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

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.