Data Sheet
RSC-4128
15
P/N 80-0206-R
© 2006 Sensory Inc.
The entire 1MByte of Constant/Code Space can be read with the following conditions.
The upper addresses
A[19:16] are generated from Bits[3:0] of Extended Addressing Register (register D2):
1) The MOVX instruction is used to read and Bit 4 (“rw”) of Extended Addressing
Register (register D2) is programmed to “0”.
The first 128KBytes (addresses 00000H-1FFFFH; Code Banks 0 & 1) can be accessed in two additional ways. For
these two cases, addresses A[19:17] are forced to zero by the RSC4x, and A[16] is generated from Bit 5 (“cb1”) of
the Extended Addressing Register. A “0” in “cb1” selects Code Bank 0 and a “1” selects Code Bank 1:
2) The processor fetches instructions from the active Code Bank.
3) The MOVC instruction is used to read from or write to the active Code Bank.
Data Space
Data Space is always external to the chip and can be up to 1MByte. Typical uses of this space are for storage of
SD recognition template data and/or recorded audio data, and frequently the data is volatile. –RDF is the read
strobe and –WRD is the write strobe. A special bit in the Extended Addressing Register must be set high to allow
the processor to read from the data space using the MOVX instruction. When the “rw” bit (Bit 4 of Register D2) is
set, the MOVX instruction reads from the Data Space.
When writing to Data Space, the MOVX instruction generates a –WRD strobe, regardless of the state of the “rw” bit.
Data space can be accessed in two ways. For both cases, upper addresses A[19:16] are generated from bits [3:0]
of Extended Addressing Register:
1) The MOVX instruction is used to read and bit 4 (“RW”) of Extended
Addressing Register (register D2) is programmed to “1”.
2) The MOVX instruction is used to write.
Extended Address Register
0D2H
R/W
ExtAdd
Bit [7:6]
(Unused)
Bit 5
cb1
0:
MOVC reads/writes and processor fetches access addresses
00000H-0FFFFH of Constant/Code Space (Code Bank 0)
1:
MOVC reads/writes and processor fetches access addresses
10000H-1FFFFH of Constant/Code Space (Code Bank 1)
Cleared on reset.
Bit 4
rw
0:
MOVX reads access Constant/Code Space
1:
MOVX reads access Data Space
Cleared on reset.
Bits [3:0]
“eda” bits – extended address bits [19:16]
used by MOVX to generate addresses bits A[19:16] of Data and/or Constant/Code Space.
Cleared on reset.
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