PIC24HJ12GP201ESLASHML datasheet(97/234 Pages) MICROCHIP

97 / 234 page

Preliminary

DS70282B-page 95

PIC24HJ12GP201/202

9.4.5.2

Changing the Configuration

Choosing the configuration requires review of all

peripheral pin selects and their pin assignments,

especially those that will not be used in the application.

In all cases, unused pin selectable peripherals should

be disabled completely. Unused peripherals should

have their inputs assigned to an unused RPn pin

function. I/O pins with unused RPn functions should be

configured with the null peripheral output.

The assignment of a peripheral to a particular pin does

not automatically perform any other configuration of

the pin’s I/O circuitry. This means adding a pin

selectable output to a pin can inadvertently drive an

existing peripheral input when the output is driven.

Programmers must be familiar with the behavior of

other fixed peripherals that share a remappable pin,

and know when to enable or disable them. To be safe,

fixed digital peripherals that share the same pin should

be disabled when not in use.

9.4.5.3

Pin Operation

Configuring a remappable pin for a specific peripheral

does not automatically turn that feature on. The

peripheral

must

specifically

configured

for

operation and enabled, as if it were tied to a fixed pin.

Where this happens in the application code

(immediately following device Reset and peripheral

configuration, or inside the main application routine)

depends on the peripheral and its use in the

application.

9.4.5.4

Analog Function

A final consideration is that peripheral pin select

functions

neither

override

analog

inputs

nor

reconfigure pins with analog functions for digital I/O. If

a pin is configured as an analog input on device Reset,

it must be explicitly reconfigured as digital I/O when

used with a peripheral pin select.

9.4.5.5

Configuration Example

Example 9-2 shows a configuration for bidirectional

communication with flow control using UART1. The

following input and output functions are used:

• Input Functions: U1RX, U1CTS

• Output Functions: U1TX, U1RTS

EXAMPLE 9-2:

CONFIGURING UART1

INPUT AND OUTPUT

FUNCTIONS

//*************************************

// Unlock Registers

//*************************************

asm volatile ( "mov #OSCCONL, w1

\n"

"mov #0x46, w2

\n"

"mov #0x57, w3

\n"

"mov.b w2, [w1]

\n"

"mov.b w3, [w1]

\n"

"bclr OSCCON, 6");

//***************************

// Configure Input Functions

// (See Table 9-1)

//***************************

// Assign U1Rx To Pin RP0

//***************************

RPINR18bits.U1RXR = 0;

//***************************

// Assign U1CTS To Pin RP1

//***************************

RPINR18bits.U1CTSR = 1;

//***************************

// Configure Output Functions

// (See Table 9-2)

//***************************

// Assign U1Tx To Pin RP2

//***************************

RPOR1bits.RP2R = 3;

//***************************

// Assign U1RTS To Pin RP3

//***************************

RPOR1bits.RP3R = 4;

//*************************************

// Lock Registers

//*************************************

asm volatile ( "mov #OSCCONL, w1

\n"

"mov #0x46, w2

\n"

"mov #0x57, w3

\n"

"mov.b w2, [w1]

\n"

"mov.b w3, [w1]

\n"

"bset OSCCON, 6");

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