Thread: Trying to follow C18 interrupt context code...
View Single Post
  #5   Spotlight this post!  
Unread 21-12-2006, 00:34
dcbrown dcbrown is offline
Registered User
AKA: Bud
no team
Team Role: Mentor
  
Join Date: Jan 2005
Rookie Year: 2005
Location: Hollis,NH
Posts: 236
dcbrown has much to be proud ofdcbrown has much to be proud ofdcbrown has much to be proud ofdcbrown has much to be proud ofdcbrown has much to be proud ofdcbrown has much to be proud ofdcbrown has much to be proud ofdcbrown has much to be proud ofdcbrown has much to be proud ofdcbrown has much to be proud of
Re: Trying to follow C18 interrupt context code...
Mike,

Thanks - I believe you are correct. I'm re-reading the PIC18 specification. Although I read the spec as indicating that an access to the POSTINC, PREINC, or POSTDEC locations cause the associated FSR to be appropriately incremented or decremented after an indirect access I think what I should have read in addition was "per instruction cycle".

So a MOVF POSTINC1, F, ACCESS will do a post increment at the end of the instruction cycle and not at the end of the individual accesses. Subtle but obviously very important distinction.

The MOVFF since it is two instruction cycles can increment/decrement on each access but the MOVF is only a single instruction cycle.

Thanks again,
Bud
Last edited by dcbrown : 21-12-2006 at 00:42.