T89C5115 ATMEL Corporation, T89C5115 Datasheet - Page 21

no-image

T89C5115

Manufacturer Part Number
T89C5115
Description
Low Pin Count 8-bit MCU with A/D Converter and 16-Kbytes of Flash Memory
Manufacturer
ATMEL Corporation
Datasheet

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
T89C5115-RATIM
Manufacturer:
TI
Quantity:
1 474
Part Number:
T89C5115-RATIM
Manufacturer:
Atmel
Quantity:
10 000
Part Number:
T89C5115-SISIM
Manufacturer:
Atmel
Quantity:
10 000
Data Memory
Internal Space
Lower 128 Bytes RAM
4128A–8051–04/02
The T89C5115 provides data memory access in two different spaces:
The internal space mapped in three separate segments:
A fourth internal segment is available but dedicated to Special Function Registers,
SFRs, (addresses 80h to FFh) accessible by direct addressing mode.
Figure 7 shows the internal data memory spaces organization.
Figure 7. Internal Memory – RAM
The lower 128 bytes of RAM (see Figure 7) are accessible from address 00h to 7Fh
using direct or indirect addressing modes. The lowest 32 bytes are grouped into 4 banks
of 8 registers (R0 to R7). Two bits RS0 and RS1 in PSW register (see Figure 16) select
which bank is in use according to Table . This allows more efficient use of code space,
since register instructions are shorter than instructions that use direct addressing, and
can be used for context switching in interrupt service routines.
Table 15. Register Bank Selection
The next 16 bytes above the register banks form a block of bit-addressable memory
space. The C51 instruction set includes a wide selection of single-bit instructions, and
the 128 bits in this area can be directly addressed by these instructions. The bit
addresses in this area are 00h to 7Fh.
the lower 128 bytes RAM segment.
the upper 128 bytes RAM segment.
the expanded 256 bytes RAM segment (ERAM).
RS1
0
0
1
1
FFh
00h
Internal ERAM
256 bytes
RS0
0
1
0
1
FFh
80h
7Fh
00h
Description
Register bank 0 from 00h to 07h
Register bank 0 from 08h to 0Fh
Register bank 0 from 10h to 17h
Register bank 0 from 18h to 1Fh
indirect addressing
direct or indirect
Internal RAM
Internal RAM
addressing
128 bytes
128 bytes
Upper
Lower
FFh
80h
direct addressing
Registers
Function
Special
T89C5115
21

Related parts for T89C5115