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 the command UnLockPPS to enable setting of the PPS if the PPS have been previously locked, and, you can, optionally, use LockPPS to prevent unintentional change to PPS settings.
GCBASIC 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
