Rainbow-electronics AT89LP214 Manual de usuario descargar pdf (Pagina 25)

3538A–MICRO–7/06

AT89LP213/214 [Preliminary]

Figure 13-5. Push-pull Output

13.2 Port 1 Analog Functions

The AT89LP213/214 incorporates an analog comparator. In order to give the best analog perfor-

mance and minimize power consumption, pins that are being used for analog functions must

have both their digital outputs and digital inputs disabled. Digital outputs are disabled by putting

the port pins into the input-only mode as described in “Port Configuration” on page 22. Digital

inputs on P1.0 and P1.1 are disabled whenever the Analog Comparator is enabled by setting the

CEN bit in ACSR. CEN forces the PWD

input on P1.0 and P1.1 low, thereby disabling the

Schmitt trigger circuitry. P1.0 and P1.1 will always default to input-only mode after reset regard-

less of the state of the Tristate-Port Fuse.

13.3 Port Read-modify-write

A read from a port will read either the state of the pins or the state of the port register depending

on which instruction is used. Simple read instructions will always access the port pins directly.

Read-modify-write instructions, which read a value, possibly modify it, and then write it back, will

always access the port register. This includes bit write instructions such as CLR or SETB as they

actually read the entire port, modify a single bit, then write the data back to the entire port. See

Table 13-3 for a complete list of Read-modify-write instruction which may access the ports.

Port

From Port

Input

Data

PWD

Table 13-3. Port Read-modify-write Instructions

Mnemonic Instruction Example

ANL Logical AND ANL P1, A

ORL Logical OR ORL P1, A

XRL Logical EX-OR XRL P1, A

JBC Jump if bit set and clear bit JBC P3.0, LABEL

CPL Complement bit CPL P3.1

INC Increment INC P1

DEC Decrement DEC P3

DJNZ Decrement and jump if not zero DJNZ P3, LABEL

MOV PX.Y, C Move carry to bit Y of Port X MOV P1.0, C

CLR PX.Y Clear bit Y of Port X CLR P1.1

SETB PX.Y Set bit Y of Port X SETB P3.2

1 2 ... 20 21 22 23 24 25 26 27 28 29 30 ... 89 90

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