Rainbow-electronics T89C51CC01 Manual do Utilizador descarregar pdf (Página 6)

T89C51CC01

Rev. D – 17-Dec-01

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

, 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:

Timer0counterinput

P3.5 / T1:

Timer1counterinput

P3.6 / WR

External Data Memory write strobe; latches the data byte from port 0 into the external data memory

P3.7 / RD

External Data Memory read strobe; Enables the external data memory.

It can drive CMOS inputs without external pull-ups.

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.

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

secondary functions are assigned to the two pins of port 4 as follows:

P4.0 / TxDC:

Transmitter output of CAN controller

P4.1 / RxDC:

Receiver input of CAN controller.

It can drive CMOS inputs without external pull-ups.

Pin Name Type Description

1 2 3 4 5 6 7 8 9 10 11 ... 148 149

Sem comentários

Rainbow-electronics T89C51CC01 Manual do Utilizador Página 6