peripheral_pin_select_for_microchip_microcontrollers

Peripheral Pin Select for Microchip microcontrollers.

Introduction:

Peripheral Pin Select (PPS) enables the digital peripheral I/O pins to be changed to support mapping of external pins to different pins.

In older 8-bit Microchip devices, a peripheral was hard-wired to a specific pin (example: PWM1 output on pin RC5).

PPS allows you to choose from a number of output and input pins to connect to the digital peripheral.

This can be extremely useful for routing circuit boards.

There are cases where a change of I/O position can make a circuit board easier to route Sometimes mistakes are found too late to fix so having the option to change a pinout mapping in software rather than creating a new printed circuit board can be very helpful.

You must use both commands UnLockPPS and LockPPS to complete any PPS changes. Great Cow BASIC includes these two macros to ensure this process is handled correctly.

Also, see http://microchip.wikidot.com/8bit:pps for more information.

Example:

    'Please check configuration before using on an alternative microcontroller.

    #chip 16f18855,32
    #option explicit

    'Set the PPS of the I2C and the RS232 ports.
    #startup InitPPS, 85
    Sub InitPPS
      LOCKPPS
        RC0PPS = 0x0010       'RC0->EUSART:TX;
        RXPPS  = 0x0011       'RC1->EUSART:RX;

        SSP1CLKPPS = 0x14     'RC3->MSSP1:SCL1;
        SSP1DATPPS = 0x13     'RC4->MSSP1:SDA1;
        RC3PPS = 0x15         'RC3->MSSP1:SCL1;
        RC4PPS = 0x14         'RC4->MSSP1:SDA1;
      UnLockPPS
    End Sub

For more help, see: UnlockPPS and LockPPS.