pic24hj16gp304 Microchip Technology Inc., pic24hj16gp304 Datasheet - Page 101

• Manufacturer Part Number: pic24hj16gp304
• Description: High-performance, 16-bit Microcontrollers
• Manufacturer: Microchip Technology Inc.

9.4.5.2
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. Program-
mers 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 digi-
tal peripherals that share the same pin should be dis-
abled when not in use.
9.4.5.3
Configuring a remappable pin for a specific peripheral
does not automatically turn that feature on. The periph-
eral must be specifically configured for an 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
A final consideration is that peripheral pin select func-
tions neither override analog inputs nor reconfigure
pins with analog functions for digital I/O. If a pin is con-
figured 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
Example 9-2 shows a configuration for bidirectional
communication with flow control using UART1. The fol-
lowing input and output functions are used:
• Input Functions: U1RX, U1CTS
• Output Functions: U1TX, U1RTS
© 2007 Microchip Technology Inc.
PIC24HJ32GP202/204 and PIC24HJ16GP304
Changing the Configuration
Pin Operation
Analog Function
Configuration Example
Preliminary
9.5
The PIC24HJ32GP202/204 and PIC24HJ16GP304
devices implement 17 registers for remappable periph-
eral configuration:
• Input Remappable Peripheral Registers (9)
• Output Remappable Peripheral Registers (8)
EXAMPLE 9-2:
//*************************************
// Unlock Registers
//*************************************
asm volatile ( "mov #OSCCONL, w1
//***************************
// Configure Input Functions
// (See Table 9-1)
//***************************
//***************************
// Configure Output Functions
// (See Table 9-2)
//***************************
//*************************************
// Lock Registers
//*************************************
asm volatile ( "mov #OSCCONL, w1
Note:
//***************************
// Assign U1Rx To Pin RP0
//***************************
RPINR18bits.U1RXR = 0;
//***************************
// Assign U1CTS To Pin RP1
//***************************
RPINR18bits.U1CTSR = 1;
//***************************
// Assign U1Tx To Pin RP2
//***************************
RPOR1bits.RP2R = 3;
//***************************
// Assign U1RTS To Pin RP3
//***************************
RPOR1bits.RP3R = 4;
Peripheral Pin Select Registers
Input and Output Register values can only
be changed if OSCCON[IOLOCK] = 0.
See Section 9.4.4.1 “Control Register
Lock” for a specific command sequence.
"mov.b w3, [w1]
"bclr OSCCON, 6");
"mov.b w3, [w1]
"bset OSCCON, 6");
"mov #0x46, w2
"mov #0x57, w3
"mov.b w2, [w1]
"mov #0x46, w2
"mov #0x57, w3
"mov.b w2, [w1]
CONFIGURING UART1
INPUT AND OUTPUT
FUNCTIONS
DS70289A-page 99
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