Mitsubishi Motors DS5000TK - Manual (Page 28)

USER’S GUIDE
050396 27/173
28
Special Function Registers
The Secure Microcontroller uses Special Function Reg-
isters (SFRs) to control most functions. In many cases,
an SFR will contain 8 bits, each of which control a func-
tion or report status on a function. The SFRs reside in
register locations 80–FFh. They can be accessed using
MOV instructions with direct addressing. In addition,
some of the SFRs are bit addressable. This can be par-
ticularly useful when enabling a function without modify-
ing others in the register since an SFR can contain 8 un-
related control and status functions.
With a few minor exceptions documented below, the
Secure Microcontroller provides identical SFRs to a
standard 8051, plus extra locations to control unique
functions. Modifications to the standard 8051 SFR map
are as follows. The PCON register GF1 (PCON.3) and
GF0 (PCON.2) have been replaced by the Enable Pow-
er Fail Interrupt and the Enable Watchdog Timer bits re-
spectively. In addition, the Secure Microcontroller re-
quires a Timed Access procedure before allowing
software to modify the STOP mode bit (PCON.1). This is
to prevent errant software from creating a situation that
the Watchdog Timer can not recover from. The remain-
ing SFRs are either identical to the 8051 or new to the
architecture.
As with the memory map, there are some differences
between the DS5000 series and the DS5001 series
SFRs. Figures 4–12 and 4–13 show an overview of their
respective SFR maps. Following these figures are de-
tailed descriptions. In the case where a particular SFR
has differences between the DS5000 and
DS5001/DS5002, those differences will be pointed out
under the particular register. In some cases, the
DS5001 and DS5002 have registers that do not appear
in the DS5000. This is also highlighted under the partic-
ular register.