SAA-XC886CLM Datasheet, PDF (30/134 Pages) Infineon Technologies AG – 8-Bit Single Chip Microcontroller

SAA-XC886CLM
Functional Description
SFR Address
(from CPU)
MOD_PAGE.PAGE
rw
SFR Data
(to/from CPU)
PAGE 0
SFR0
SFR1
SFRx
PAGE 1
SFR0
SFR1
SFRy
PAGE q
SFR0
SFR1
SFRz
Module
Figure 8 Address Extension by Paging
In order to access a register located in a page different from the actual one, the current
page must be exited. This is done by reprogramming the bit field PAGE in the page
register. Only then can the desired access be performed.
If an interrupt routine is initiated between the page register access and the module
register access, and the interrupt needs to access a register located in another page, the
current page setting can be saved, the new one programmed and the old page setting
restored. This is possible with the storage fields STx (x = 0 - 3) for the save and restore
action of the current page setting. By indicating which storage bit field should be used in
parallel with the new page value, a single write operation can:
• Save the contents of PAGE in STx before overwriting with the new value
(this is done in the beginning of the interrupt routine to save the current page setting
and program the new page number); or
Data Sheet
23
V1.1, 2010-08