Datasheet

ROM-Resident Routines
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor 127
During the software execution, it does not consume any dedicated RAM location, the run-time heap will
extend the system stack, all other RAM location will not be affected.
Figure 8-9. Data Block Format for ROM-Resident Routines
The control and data bytes are described below.
• Bus speed — This one byte indicates the operating bus speed of the MCU. The value of this byte
should be equal to 4 times the bus speed. E.g., for a 4MHz bus, the value is 16 ($10). This control
byte is useful where the MCU clock source is switched between the PLL clock and the crystal clock.
• Data size — This one byte indicates the number of bytes in the data array that are to be
manipulated. The maximum data array size is 255. Routines EE_WRITE and EE_READ are
restricted to manipulate a data array between 7 to 15 bytes. Whereas routines ERARNGE and
MON_ERARNGE do not manipulate a data array, thus, this data size byte has no meaning.
• Start address — These two bytes, high byte followed by low byte, indicate the start address of the
FLASH memory to be manipulated.
• Data array — This data array contains data that are to be manipulated. Data in this array are
programmed to FLASH memory by the programming routines: PRGRNGE, MON_PRGRNGE,
EE_WRITE. For the read routines: LDRNGE and EE_READ, data is read from FLASH and stored
in this array.
8.5.1 PRGRNGE
PRGRNGE is used to program a range of FLASH locations with data loaded into the data array.
Table 8-11. PRGRNGE Routine
Routine Name PRGRNGE
Routine Description Program a range of locations
Calling Address $FC34
Stack Used 15 bytes
Data Block Format
Bus speed (BUS_SPD)
Data size (DATASIZE)
Start address high (ADDRH)
Start address (ADDRL)
Data 1 (DATA1)
:
Data N (DATAN)
DATA SIZE (DATASIZE)
START ADDRESS HIGH (ADDRH)
START ADDRESS LOW (ADDRL)
DATA 0
DATA 1
BUS SPEED (BUS_SPD)
FILE_PTR
DATA N
DATA
ARRAY
$XXXX
DATA
BLOCK
ADDRESS AS POINTER
RAM