Mitsubishi DS907x SIP, DS5000TK manual Special Function Registers

USER'S GUIDE

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 The PCON register GF1 (PCON.3) and GF0 (PCON.2) have been replaced by the Enable Pow- er Fail Interrupt and the Enable Watchdog Timer bits re-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.

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