Custom Interrupts - PICmicro

Here are a few examples for such interrupts using PICmicro chips. To create interrupts that are not shown below you will have to refer to the device datasheet. Once the code has been placed into the custom interrupt properties dialog, the interrupt can be enabled and disabled like any of the standard Flowcode Interrupts.

USART receive - This can be nicely integrated with the Flowcode RS232 component.

Comparator - Example of the use of a function not supported by Flowcode.

Timer1 rollover - An example of the use of another unsupported, but potentially useful, function.

Target PIC Processor ( PIC16F877A )

(Note: For other PIC devices you may have to refer to the device datasheet to obtain the correct code)

USART receive

The Flowcode RS232 component can be used to set the Baud rate and configure the mode of operation, and the ReceiveRS232Char function can be used in the handler macro to read the data (clearing the interrupt).

Enable code:

intcon.PEIE = 1; // Enable peripheral interrupts

intcon.GIE = 1; // Enable global interrupts

pie1.RCIE = 1; // Enable USART receive interrupts

Disable code:

pie1.RCIE = 0; // Disable USART receive interrupts

Handler code:

if (pir1 & (1 << RCIF))

{

FCM_%n(); // call selected macro

clear_bit(pir1, RCIF); // clear interrupt

}

<img>

Analogue comparator

Enable code:

intcon.PEIE = 1; // Enable peripheral interrupts

intcon.GIE = 1; // Enable global interrupts

pie1.CCP1IE = 1; // Enable Capture Compare interrupts

Disable code:

pie1.CCP1IE = 0; // Disable Capture Compare Interrupts

Handler code:

if (pir1 & (1 << CCP1IF))

{ FCM_%n();

clear_bit(pir1, CCP1IF);

}

The state of the comparator input can be read into a Flowcode variable 'compstate' with the following C code line:

FCV_COMPSTATE = CCPR1L | ( CCPR1H << 8 );

** compstate must be declared as an integer variable ** 

<img>

Timer1 rollover

Enable code:

t1con = 0x79; // Start timer with Internal clock source, prescaler = 1:8

intcon.PEIE = 1; // Enable peripheral interrupts

intcon.GIE = 1; // Enable global interrupts

pie1.TMR1IE = 1; // Enable Capture Compare interrupts

Disable code:

pie1.TMR1IE = 0; // Disable Capture Compare interrupts

Handler code:

if (pir1 & (1 << TMR1IF))

{

FCM_%n();

clear_bit(pir1, TMR1IF);

}

The captured 16-bit count value can be read into a Flowcode variable 'captval' with the following C code line:

FCV_CAPTVAL = TMR1L | ( TMR1H << 8 );

** captval must be declared as an integer variable ** 

<img>