MC9S08DN60_08 Datasheet, PDF (47/356 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 4 Memory
4.4 RAM
The MC9S08DN60 Series includes static RAM. The locations in RAM below 0x0100 can be accessed
using the more efficient direct addressing mode, and any single bit in this area can be accessed with the bit
manipulation instructions (BCLR, BSET, BRCLR, and BRSET). Locating the most frequently accessed
program variables in this area of RAM is preferred.
The RAM retains data while the MCU is in low-power wait, stop2, or stop3 mode. At power-on the
contents of RAM are uninitialized. RAM data is unaffected by any reset if the supply voltage does not drop
below the minimum value for RAM retention (V_RAM).
For compatibility with M68HC05 MCUs, the HCS08 resets the stack pointer to 0x00FF. In the
MC9S08DN60 Series, it is usually best to reinitialize the stack pointer to the top of the RAM so the direct
page RAM can be used for frequently accessed RAM variables and bit-addressable program variables.
Include the following 2-instruction sequence in your reset initialization routine (where RamLast is equated
to the highest address of the RAM in the Freescale Semiconductor equate file).
LDHX
TXS
#RamLast+1
;point one past RAM
;SP<-(H:X-1)
When security is enabled, the RAM is considered a secure memory resource and is not accessible through
BDM or code executing from non-secure memory. See Section 4.5.9, “Security”, for a detailed description
of the security feature.
4.5 Flash and EEPROM
MC9S08DN60 Series devices include Flash and EEPROM memory intended primarily for program and
data storage. In-circuit programming allows the operating program and data to be loaded into Flash and
EEPROM, respectively, after final assembly of the application product. It is possible to program the arrays
through the single-wire background debug interface. Because no special voltages are needed for erase and
programming operations, in-application programming is also possible through other software-controlled
communication paths. For a more detailed discussion of in-circuit and in-application programming, refer
to the HCS08 Family Reference Manual, Volume I, Freescale Semiconductor document order number
HCS08RMv1.
4.5.1 Features
Features of the Flash and EEPROM memory include:
• Array size (see Table 1-1 for exact array sizes)
• Flash sector size: 768 bytes
• EEPROM sector size: selectable 4-byte or 8-byte sector mapping operation
• Single power supply program and erase
• Command interface for fast program and erase operation
• Up to 100,000 program/erase cycles at typical voltage and temperature
• Flexible block protection and vector redirection
• Security feature for Flash, EEPROM, and RAM
MC9S08DN60 Series Data Sheet, Rev 3
Freescale Semiconductor
47