STC12LE5604 datasheet(71/377 Pages) STC

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Chapter 4. Configurable I/O Ports of STC12C5620AD series

4.1 I/O Ports Configurations

All I/O ports of STC12C5620AD may be independently configured to one of four modes by setting the

corresponding bit in two mode registers PxMn (x= 0 ~ 3, n = 0, 1).The four modes are quasi-bidirectional (standard

8051 port output), push-pull output, input-only or open-drain output. All port pins default to quasi-bidirectional

after reset. Each one has a Schmitt-triggered input for improved input noise rejection. Any port can drive 20mA

current, but the whole chip had better drive lower than 90mA current.

Configure I/O ports mode

P3 Configure <P3.7, P3.6, P3.5, P3.4, P3.3, P3.2, P3.1, P3.0 port> (P3 address

address B0H))

P3M0 7

P3M1 [7 0

I/O ports Mode

quasi_bidirectional(standard 8051 I/O port output

Sink Current up to 20mA , pull-up Current is 230μA ,

Because of manufactured error, the actual pull-up current is 250uA ~ 150uA

push-pull output(strong pull-up output current can be up to 20mA, resistors

need to be added to restrict current

input-only (high-impedance )

Open Drain internal

pull-up resistors should be disabled and external

pull-up resistors need to join.

Example: MOV P3M0, #10100000B

MOV

P3M1, #10010000B

;P3.7 in Open Drain mode, P3.5 in high-impedance input, P3.4 in strong push-pull output, P3.3/P3.2/P3.1/P3.0

in quasi_bidirectional/weak pull-up

/weak pull-up

P2M0 7

P2M1 [7 0

I/O ports Mode

quasi_bidirectional(standard 8051 I/O port output

Sink Current up to 20mA , pull-up Current is 230μA ,

Because of manufactured error, the actual pull-up current is 250uA ~ 150uA

push-pull output(strong pull-up output current can be up to 20mA, resistors

need to be added to restrict current

input-only (high-impedance )

Open Drain internal

pull-up resistors should be disabled and external

pull-up resistors need to join.

Example: MOV P2M0, #10100000B

MOV

P2M1, #11000000B

;P2.7 in Open Drain mode, P2.6 in strong push-pull output, P2.5 in high-impedance input, P2.4/P2.3/P2.2/

P2.1/P2.0 in quasi_bidirectional/weak pull-up

/weak pull-up

P2 Configure <P2.7, P2.6, P2.5, P2.4, P2.3, P2.2, P2.1, P2.0 port> (P2 address

address A0H))

STC12LE5604 Datasheet(PDF) 71 Page - STCmicro Technology Co,.Ltd

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