SW006012 Microchip Technology, SW006012 Datasheet - Page 115

• Manufacturer Part Number: SW006012
• Description: C COMPILER FOR DSPIC30F FAMILY
• Manufacturer: Microchip Technology
• Type: MPLAB® C30 Compilerr
• Series: PIC24 & DsPICr

Specifications of SW006012

• Supported Families: PIC24, DsPIC30F And DsPIC33F
• Core Architecture: PIC, DsPIC
• Kit Contents: Software And Docs
• Mcu Supported Families: PIC24 MCUs And DsPIC DSCs
• Tool Type: Compiler
• Processor Series: PIC24, dsPIC
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: dsPIC30F
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

7.10
© 2007 Microchip Technology Inc.
PSV USAGE WITH INTERRUPT SERVICE ROUTINES
}
A statement can be protected from interrupt using the INTERRUPT_PROTECT macro
provided above. For this example:
INTERRUPT_PROTECT(LATGbits.LATG15 ^= 1); /* Not interruptible by
The introduction of managed psv pointers and CodeGuard Security psv constant sec-
tions in MPLAB C30 v3.0 means that Interrupt Service Routines (ISRs) cannot make
any assumptions about the setting of PSVPAG. This is a migration issue for existing
applications with ISRs that reference the auto_psv constants section. In previous ver-
sions of MPLAB C30, the ISR could assume that the correct value of PSVPAG was set
during program startup (unless the programmer had explicitly changed it.)
To help mitigate this problem, two new function attributes will be introduced: auto_psv
and no_auto_psv. If an ISR references const variables or string literals using the
constants-in-code memory model, the auto_psv attribute should be added to the
function definition. This attribute will cause the compiler to preserve the previous con-
tents of PSVPAG and set it to section .const. Upon exit, the previous value of
PSVPAG will be restored. For example:
void __attribute__((interrupt, auto_psv)) myISR()
{
}
The no_auto_psv attribute is used to indicate that an ISR does not reference the
auto_psv constants section. If neither attribute is specified, the compiler will assume
auto_psv and will insert the necessary instructions to ensure correct operation at runt-
ime. A warning diagnostic message will also be issued. The warning will help alert cus-
tomers to the migration issue, and to the possibility of reducing interrupt latency by
specifying the no_auto_psv attribute.
/* This function can reference const variables and
string literals with the constants-in-code memory model. */
LATGbits.LATG2 = 0;
LATG += 0x0001;
IPC0bits.T1IP = 5;
/* No problem likely,
/* Potential HAZARD -
/* HAZARD -
single instruction bit clear
operation probably used */
First reads LATG into a W reg,
implements add operation,
then writes result to LATG */
Assigning a multiple bitfield
can generate a multiple
instruction sequence */
level 1-7 interrupt
requests and safe
at any optimization
level */
Interrupts
DS51284F-page 109