SB-27: Salvo: Updated Interrupt Control for PIC18

[Salvo Tech Support]

A Salvo user has brought it to our attention that the existing interrupt control for PIC18 can lead to lost / missed Timer0 and/or INT0 interrupts due to Read-Modify-Write issues when applied to the INTCON register.

Therefore, to avoid any chance of R-M-W artifacts on the INTCON register, Salvo for PICmicro(R) MCUs users should replace a portion of salvoincportpicc.h with:

code:

---

/* interrupt control depends on OSPIC18_INTERRUPT_MASK. Don't  */
/*  use RMW instructions (e.g. INTCON |= mask) because Timer0  */
/*  and/or INT0 bits may be lost if set during the RMW cycle.  */
#if   ( OSPIC18_INTERRUPT_MASK == 0xC0 ) || 
      ( OSPIC18_INTERRUPT_MASK == 0x80 ) || 
      ( OSPIC18_INTERRUPT_MASK == 0x40 ) || 
      ( OSPIC18_INTERRUPT_MASK == 0x00 )
      
#if !defined(OSDi)
#if   (OSPIC18_INTERRUPT_MASK == 0xC0)
#define OSDi()                          do { GIE = FALSE; PEIE = FALSE; 
                                        } while (0)
#elif (OSPIC18_INTERRUPT_MASK == 0x80)
#define OSDi()                          do { GIE = FALSE; 
                                        } while (0)
#elif (OSPIC18_INTERRUPT_MASK == 0x40)
#define OSDi()                          do { PEIE = FALSE; 
                                        } while (0)
#elif (OSPIC18_INTERRUPT_MASK == 0x00)
#define OSDi()                          
#endif
#endif
#if !defined(OSEi)
#if   (OSPIC18_INTERRUPT_MASK == 0xC0)
#define OSEi()                          do { GIE = TRUE; PEIE = TRUE; 
                                        } while (0)
#elif (OSPIC18_INTERRUPT_MASK == 0x80)
#define OSEi()                          do { GIE = TRUE; 
                                        } while (0)
#elif (OSPIC18_INTERRUPT_MASK == 0x40)
#define OSEi()                          do { PEIE = TRUE; 
                                        } while (0)
#elif (OSPIC18_INTERRUPT_MASK == 0x00)
#define OSEi()                          
#endif
#endif   
                                                                         
#else
#error portpicc.h: Invalid OSPIC18_INTERRUPT_MASK value.
#endif   

---

The same change should also be made to salvoincportiar18.h.

------------------
--------
Salvo Technical Support
Please request all tech support through the Forums.

[This message has been edited by Salvo Tech Support (edited November 23, 2005).]

[This message has been edited by aek (edited June 15, 2006).]