MC9S08DN60 Datasheet, PDF (34/354 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 3 Modes of Operation
3.6.1.2 Active BDM Enabled in Stop3 Mode
Entry into the active background mode from run mode is enabled if ENBDM in BDCSCR is set. This
register is described in Chapter 16, “Development Support.” If ENBDM is set when the CPU executes a
STOP instruction, the system clocks to the background debug logic remain active when the MCU enters
stop mode. Because of this, background debug communication remains possible. In addition, the voltage
regulator does not enter its low-power standby state but maintains full internal regulation.
Most background commands are not available in stop mode. The memory-access-with-status commands
do not allow memory access, but they report an error indicating that the MCU is in either stop or wait
mode. The BACKGROUND command can be used to wake the MCU from stop and enter active
background mode if the ENBDM bit is set. After entering background debug mode, all background
commands are available.
3.6.2 Stop2 Mode
Stop2 mode is entered by executing a STOP instruction under the conditions as shown in Table 3-1. Most
of the internal circuitry of the MCU is powered off in stop2 with the exception of the RAM. Upon entering
stop2, all I/O pin control signals are latched so that the pins retain their states during stop2.
Exit from stop2 is performed by asserting RESET. On 3M05C or older masksets only, exit from stop2 can
also be performed by asserting PTA7/ADP7/IRQ.
NOTE
On 3M05C or older masksets only, PTA7/ADP7/IRQ is an active low
wake-up and must be configured as an input prior to executing a STOP
instruction to avoid an immediate exit from stop2. PTA7/ADP7/IRQ can be
disabled as a wake-up if it is configured as a high driven output. For lowest
power consumption in stop2, this pin should not be left open when
configured as input (enable the internal pullup; or tie an external
pullup/down device; or set pin as output).
In addition, the real-time counter (RTC) can wake the MCU from stop2, if enabled.
Upon wake-up from stop2 mode, the MCU starts up as from a power-on reset (POR):
• All module control and status registers are reset
• The LVD reset function is enabled and the MCU remains in the reset state if V_DD is below the LVD
trip point (low trip point selected due to POR)
• The CPU takes the reset vector
In addition to the above, upon waking up from stop2, the PPDF bit in SPMSC2 is set. This flag is used to
direct user code to go to a stop2 recovery routine. PPDF remains set and the I/O pin states remain latched
until a 1 is written to PPDACK in SPMSC2.
MC9S08DN60 Series Data Sheet, Rev 2
34
Freescale Semiconductor