T89C5115-RATIM datasheet(6/113 Pages) ATMEL

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AT89C5115

4128F–8051–05/06

P3.0:7

I/O

Port 3:

Is an 8-bit bi-directional I/O port with internal pull-ups. Port 3 pins that have 1’s written to them are pulled

high by the internal pull-up transistors and can be used as inputs in this state. As inputs, Port 3 pins that

are being pulled low externally will be a source of current (I

IL, See section ’Electrical Characteristic’)

because of the internal pull-ups.

The output latch corresponding to a secondary function must be programmed to one for that function to

operate (except for TxD and WR). The secondary functions are assigned to the pins of port 3 as follows:

P3.0/RxD: Receiver data input (asynchronous) or data input/output (synchronous) of the serial interface

P3.1/TxD: Transmitter data output (asynchronous) or clock output (synchronous) of the serial interface

P3.2/INT0: External interrupt 0 input/timer 0 gate control input

P3.3/INT1: External interrupt 1 input/timer 1 gate control input

P3.4/T0: Timer 0 counter input

P3.5/T1: Timer 1 counter input

P3.6: Regular I/O port pin

P3.7: Regular I/O port pin

P4.0:1

I/O

Port 4:

Is an 2-bit bi-directional I/O port with internal pull-ups. Port 4 pins that have 1’s written to them are pulled

high by the internal pull-ups and can be used as inputs in this state. As inputs, Port 4 pins that are being

pulled low externally will be a source of current (IIL, on the datasheet) because of the internal pull-up

transistor.

P4.0:

P4.1:

It can drive CMOS inputs without external pull-ups.

RESET

I/O

Reset:

A high level on this pin during two machine cycles while the oscillator is running resets the device. An

internal pull-down resistor to VSS permits power-on reset using only an external capacitor to VCC.

XTAL1

XTAL1:

Input of the inverting oscillator amplifier and input of the internal clock generator circuits. To drive the

device from an external clock source, XTAL1 should be driven, while XTAL2 is left unconnected. To

operate above a frequency of 16 MHz, a duty cycle of 50% should be maintained.

XTAL2

XTAL2:

Output from the inverting oscillator amplifier.

Pin Name

Type

Description

T89C5115-RATIM Datasheet(PDF) 6 Page - ATMEL Corporation

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