MPC555CME Freescale Semiconductor, MPC555CME Datasheet - Page 222

• Manufacturer Part Number: MPC555CME
• Description: KIT EVALUATION FOR MPC555
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC555CME

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Processor To Be Evaluated: MPC555
• Data Bus Width: 32 bit
• Interface Type: RS-232
• For Use With/related Products: MPC555
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

6.8 Real-Time Clock (RTC)
MPC555
USER’S MANUAL
generate a maskable interrupt when the time base counter reaches the value pro-
grammed in one of the two reference registers. The period of the TB depends on the
driving frequency. In the MPC555 / MPC556, the TB is clocked by the TMBCLK clock.
The period for the TB is:
The state of the time base is not affected by any resets and should be initialized by
software. Reads and writes of the TB are restricted to special instructions. Separate
special-purpose registers are defined in the MPC555 / MPC556 architecture for read-
ing and writing the time base. For the MPC555 / MPC556 implementation, it is not pos-
sible to read or write the entire TB in a single instruction. Therefore, the mttb and mftb
instructions are used to move the lower half of the time base (TBL) while the mttbu
and mftbu instructions are used to move the upper half (TBU).
Two reference registers are associated with the time base: TBREF0 and TBREF1. A
maskable interrupt is generated when the TB count reaches to the value programmed
in one of the two reference registers. Two status bits in the time base control and sta-
tus register (TBSCR) indicate which one of the two reference registers generated the
interrupt.
Refer to
base registers. Refer to
ence Manual (RCPURM/AD)
MPC556 time base.
The RTC is a 32-bit counter and pre-divider used to provide a time-of-day indication to
the operating system and application software. It is clocked by the pitrtclk clock.The
counter is not affected by reset and operates in all low-power modes. It is initialized by
software. The RTC can be programmed to generate a maskable interrupt when the
time value matches the value programmed in its associated alarm register. It can also
be programmed to generate an interrupt once a second. A control and status register
is used to enable or disable the different functions and to report the interrupt source.
/
MPC556
6.13.4 System Timer Registers
SYSTEM CONFIGURATION AND PROTECTION
3.9.4 Time Base Facility (TB) — OEA
Rev. 15 October 2000
for additional information regarding the MPC555 /
T
TB
=
for diagrams and bit descriptions of time
---------------------- -
F
tmbclk
2 64
and to
RCPU Refer-
MOTOROLA
6-14