C515A_9708 Datasheet, PDF (30/182 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Memory Organization
C515A
3.5 Special Function Registers
The registers, except the program counter and the four general purpose register banks, reside in
the special function register area. The special function register area consists of two portions : the
standard special function register area and the mapped special function register area. One special
function register of the C515A (PCON1) is located in the mapped special function register area. For
accessing this mapped special function register, bit RMAP in special function register SYSCON
must be set. All other special function registers are located in the standard special function register
area which is accessed when RMAP is cleared (“0“).
Special Function Register SYSCON (Address B1H)
Bit No. MSB
7
B1H
–
6
5
4
3
– EALE RMAP –
Reset Value : XX10XX01B
LSB
2
1
0
– XMAP1 XMAP0 SYSCON
The functions of the shaded bits are not described in this section.
Bit
RMAP
–
Function
Special function register map bit
RMAP = 0 : The access to the non-mapped (standard) special function
register area is enabled.
RMAP = 1 : The access to the mapped special function register area (SFR
PCON1) is enabled.
Reserved bits for future use. Read by CPU returns undefined values.
As long as bit RMAP is set, the mapped special function register area (SFR PCON1) can be
accessed. This bit is not cleared by hardware automatically. Thus, when non-mapped/mapped
registers are to be accessed, the bit RMAP must be cleared/set respectively by software.
The 49 special function registers (SFRs) in the standard and mapped SFR area include pointers
and registers that provide an interface between the CPU and the other on-chip peripherals. All SFRs
with addresses where address bits 0-2 are 0 (e.g. 80H, 88H, 90H, 98H, ..., F8H, FFH) are
bitaddressable. The SFRs of the C515A are listed in table 3-1 and table 3-2. Table 3-2 illustrates
the contents of the SFRs in numeric order of their addresses.
Semiconductor Group
3-11
1997-08-01