GCBASIC documentation
Compiler Directives

Syntax:

    #startup SubName  [priority]

Explanation:

#startup is used in include files to automatically insert initialisation routines. If a define or subroutine from the file is used in the program, then the specified subroutine will be called.

The priority parameter to #startup supports setting the priority of the subroutines for all the libraries in a project.

Subroutines will be called in order from smallest to largest priority number.

InitSys has priority 80, lowlevel communication routines have the priority of 90
All other subroutines default to 100.

Notes: Limitations on this directive are:

#startup may only occur once within a source file.

No parameters can be passed to the subroutine that is specified.

Example 1:

This example, from the hardware I2C library, sets the subroutine with the priority of 90.

    #startup HI2CInit, 90

Example 2:

This example would be included in user code to ensure the PPS settings are set prior to use of the MSSP or USART.

    #chip 16f18855,32
    #option explicit

    'Set the PPS of the I2C and the RS232 ports.
    #startup InitPPS, 85          ' <<< registering InitPPS to run automatically at startup, before priority-90 routines
    Sub InitPPS
      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;
    End Sub

Key line: #startup InitPPS, 85 — registers InitPPS to run automatically at compile-time-assigned priority 85, which is lower (and therefore runs earlier) than the I2C library’s own priority-90 startup routine, ensuring the PPS pin routing is in place before the MSSP/USART hardware initialises.

See Also: