st10f273m STMicroelectronics, st10f273m Datasheet - Page 22

• Manufacturer Part Number: st10f273m
• Description: 16-bit Mcu With 512 Kbyte Flash Memory And 36 Kbyte Ram
• Manufacturer: STMicroelectronics

Memory organization
Note:
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IRAM: 2 Kbytes of on-chip internal RAM (dual-port) is provided as a storage for data,
system stack, general purpose register banks and code. A register bank is 16 Wordwide (R0
to R15) and / or Bytewide (RL0, RH0, …, RL7, RH7) general purpose registers group.
XRAM: 34 Kbytes of on-chip extension RAM (single port XRAM) is provided as a storage for
data, user stack and code.
The XRAM is divided into two areas, the first 2 Kbytes named XRAM1 and the second
32 Kbytes named XRAM2, connected to the internal XBUS and are accessed like an
external memory in 16-bit demultiplexed bus-mode without wait state or read/write delay
(50ns access at 40 MHz CPU clock). Byte and Word accesses are allowed.
The XRAM1 address range is 00’E000h - 00’E7FFh if XPEN (bit 2 of SYSCON register),
and XRAM1EN (bit 2 of XPERCON register) are set.
If XRAM1EN or XPEN is cleared, then any access in the address range 00’E000h -
corresponding to address matching ADDRSELx register.
The XRAM2 address range is F’0000h - F’7FFFFh if XPEN (bit 2 of SYSCON register), and
XRAM2EN (bit 3 of XPERCON register) are set.
If bit XPEN is cleared, then any access in the address range programmed for XRAM2 will be
directed to external memory interface, using the BUSCONx register corresponding to
address matching ADDRSELx register.
The 16 kbytes lower portion of the XRAM2 (address range F’0000h - F’3FFFFh) represents
also the Standby RAM, which can be maintained biased through EA / V
main supply V
As the XRAM appears like external memory, it cannot be used as system stack or as
register banks. The XRAM is not provided for single bit storage and therefore is not bit
addressable.
SFR/ESFR: 1024 bytes (2 x 512 bytes) of address space is reserved for the special function
register (SFR) areas. SFRs are Wordwide registers which are used to control and to monitor
the function of the different on-chip units.
CAN1: Address range 00’EF00h - 00’EFFFh is reserved for the CAN1 Module access. The
CAN1 is enabled by setting XPEN bit 2 of the SYSCON register and by setting CAN1EN bit
0 of the XPERCON register. Accesses to the CAN Module use demultiplexed addresses
and a 16-bit data bus (only word accesses are possible). Two wait states give an access
time of 100ns at 40 MHz CPU clock. No tri-state wait states are used.
CAN2: Address range 00’EE00h - 00’EEFFh is reserved for the CAN2 Module access. The
CAN2 is enabled by setting XPEN bit 2 of the SYSCON register and by setting CAN2EN bit
1 of the new XPERCON register. Accesses to the CAN Module use demultiplexed
addresses and a 16-bit data bus (only word accesses are possible). Two wait states give an
access time of 100ns at 40 MHz CPU clock. No tri-state wait states are used.
If one or the two CAN modules are used, Port 4 cannot be programmed to output all eight
segment address lines. Thus, only four segment address lines can be used, reducing the
external memory space to 5 Mbytes (1 Mbyte per CS line).
RTC: Address range 00’ED00h - 00’EDFFh is reserved for the RTC Module access. The
RTC is enabled by setting XPEN bit 2 of the SYSCON register and bit 4 of the XPERCON
register. Accesses to the RTC Module use demultiplexed addresses and a 16-bit data bus
(only word accesses are possible). Two waitstates give an access time of 100ns at 40 MHz
CPU clock. No tristate waitstate is used.
00’E7FFh will be directed to external memory interface, using the BUSCONx register
DD
is turned off.
STBY
pin when the
ST10F273M