DSPIC30F2020AT-30EMM datasheet(79/286 Pages) MICROCHIP

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Preliminary

DS70178C-page 77

dsPIC30F1010/202X

6.0

I/O PORTS

All of the device pins (except VDD, VSS, MCLR and

OSC1/CLKI) are shared between the peripherals and

the parallel I/O ports.

All I/O input ports feature Schmitt Trigger inputs for

improved noise immunity.

6.1

Parallel I/O (PIO) Ports

When a peripheral is enabled and the peripheral is

actively driving an associated pin, the use of the pin as

a general purpose output pin is disabled. The I/O pin

may be read, but the output driver for the parallel port

bit will be disabled. If a peripheral is enabled, but the

peripheral is not actively driving a pin, that pin may be

driven by a port.

All port pins have three registers directly associated

with the operation of the port pin. The data direction

or an output. If the data direction bit is a ‘1’, then the pin

is an input. All port pins are defined as inputs after a

Reset. Reads from the latch (LATx), read the latch.

Writes to the latch, write the latch (LATx). Reads from

the port (PORTx), read the port pins, and writes to the

port pins, write the latch (LATx).

Any bit and its associated data and control registers

that are not valid for a particular device will be

disabled. That means the corresponding LATx and

TRISx registers and the port pin will read as zeros.

When a pin is shared with another peripheral or func-

tion that is defined as an input only, it is nevertheless

regarded as a dedicated port because there is no

other competing source of outputs.

A Parallel I/O (PIO) port that shares a pin with a periph-

eral is, in general, subservient to the peripheral. The

peripheral’s output buffer data and control signals are

provided to a pair of multiplexers. The multiplexers

select whether the peripheral or the associated port

has ownership of the output data and control signals of

the I/O pad cell. Figure 6-1 shows how ports are shared

with other peripherals, and the associated I/O cell (pad)

to which they are connected. Table 6-1 and Table 6-2

show the register formats for the shared ports, PORTA

through PORTF, for the dsPIC30F1010/2020 and

PORTA through PORTG for the dsPIC30F2023 device,

respectively.

FIGURE 6-1:

BLOCK DIAGRAM OF A SHARED PORT STRUCTURE

Note: This data sheet summarizes features of this group

of dsPIC30F devices and is not intended to be a complete

reference source. For more information on the CPU,

peripherals, register descriptions and general device

functionality, refer to the “dsPIC30F Family Reference

Manual” (DS70046).

WR LAT +

TRIS Latch

I/O Pad

WR Port

Data Bus

Data Latch

Read LAT

Read Port

Read TRIS

WR TRIS

Peripheral Output Data

Output Enable

Peripheral Input Data

I/O Cell

Peripheral Module

Peripheral Output Enable

PIO Module

Output Multiplexers

Output Data

Input Data

Peripheral Module Enable

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