User’s Manual
C166S V1 SubSystem
Memory Organization
User’s Manual
4-7
V 1.6, 2001-08
When accessing registers in the ESFR area using 8-bit addresses or direct bit
addressing, the EXTend Register (EXTR) instruction is required before accessing
registers in the ESFR area, in order to switch the short-addressing mechanism from the
standard SFR area to the ESFR area. This is not required for 16-bit and indirect
addresses. The GPRs R15...R0 are duplicated, i.e., they are accessible within both
register blocks via short 2-, 4- or 8-bit addresses without switching.
Example 1:
EXTR
#4
;Switch to ESFR area for the next 4 instructions
MOV
ODP2, #data16
;ODP2 (ESFR register) uses 8-bit reg addressing
BFLDL DP6, #mask, #data8 ;DP6 (ESFR register) bit addressing for bit fields
BSET
DP6.7
;DP6 (ESFR register) bit addressing for single bits
MOV
T8REL, R1
;T8REL uses 16-bit address, R1 is duplicated
…
;
…
and also accessible via the ESFR mode
;(EXTR is not required for this access)
;-------
;-------------------
;The scope of the EXTR #4 instruction ends here!
MOV
T8REL, R1
;T8REL uses 16-bit address, R1 is duplicated
…
;
…
and does not require switching
In order to minimize the switching of SFR banks, the ESFR area holds registers that are
mainly required for initialization and mode selection. Registers that need to be accessed
frequently are allocated to the standard SFR area, wherever possible.
Note: The tools are equipped to monitor accesses to the ESFR area and will
automatically insert EXTR instructions, switch the SFR bank address, or issue a
warning in case of missing or excessive EXTR instructions.
4.3.3
PEC Source and Destination Pointers
The 16 (24/32) word locations for the 8 (12/16) PEC channels in the DPRAM from
00’FCE0h (00’FCD0h/00’FCC0h) to 00’FCFEh (just below the bit-addressable section)
are provided as source and destination address pointers for data transfers on the PEC
channels. Each channel uses a pair of pointers stored in two subsequent word locations
with the SouRCe Pointer (SRCPx) on the lower and the DeSTination Pointer (DSTPx)
on the higher word address.
Whenever a PEC data transfer is performed, the pair of SRCPx and DSTPx selected by
the specified PEC channel number is accessed independent of the current DPP register
contents; also, the locations referred to by these pointers are accessed independently of
the current DPP register contents. If a PEC channel is not used, the corresponding
pointer location area is available and can be used for word or byte data storage or for
instructions.
For more details about use of SRCPx and DSTPx for PEC data transfer, see “Interrupt
and Exception Execution”
Section 3.4
.
Содержание C166S V1 SubSystem
Страница 10: ...User s Manual C166S V1 SubSystem User s Manual I 6 V 1 6 2001 08...
Страница 16: ...User s Manual C166S V1 SubSystem Introduction User s Manual 1 6 V 1 6 2001 08...
Страница 126: ...User s Manual C166S V1 SubSystem Central Processing Unit User s Manual 3 96 V 1 6 2001 08...
Страница 178: ...User s Manual C166S V1 SubSystem Memory Organization User s Manual 4 52 V 1 6 2001 08...
Страница 206: ...User s Manual C166S V1 SubSystem Instruction Set User s Manual 5 28 V 1 6 2001 08...
Страница 306: ...User s Manual C166S V1 SubSystem Detailed Instruction Set User s Manual 6 100 V 1 6 2001 08...
Страница 362: ...User s Manual C166S V1 SubSystem The External Bus Interface User s Manual 8 40 V 1 6 2001 08...
Страница 452: ...User s Manual C166S V1 SubSystem General Purpose Timer Unit User s Manual 12 44 V 1 6 2001 08...
Страница 454: ...User s Manual C166S V1 SubSystem Instruction Index User s Manual 13 2 V 1 6 2001 08...
Страница 459: ......