MC9S12HY64 Datasheet, PDF (734/792 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

Electrical Characteristics
A.3 NVM
A.3.1 Timing Parameters
The time base for all NVM program or erase operations is derived from the bus clock using the FCLKDIV
register. The frequency of this derived clock must be set within the limits specified as f_NVMOP. The NVM
module does not have any means to monitor the frequency and will not prevent program or erase operation
at frequencies above or below the specified minimum. When attempting to program or erase the NVM
module at a lower frequency, a full program or erase transition is not assured.
The following sections provide equations which can be used to determine the time required to execute
specific flash commands. All timing parameters are a function of the bus clock frequency, f_NVMBUS. All
program and erase times are also a function of the NVM operating frequency, f_NVMOP. A summary of key
timing parameters can be found in Table A-16.
A.3.1.1 Erase Verify All Blocks (Blank Check) (FCMD=0x01)
The time required to perform a blank check on all blocks is dependent on the location of the first non-blank
word starting at relative address zero. It takes one bus cycle per phrase to verify plus a setup of the
command. Assuming that no non-blank location is found, then the time to erase verify all blocks is given
by:
for 64 Kbyte P-Flash and 4 Kbyte D-Flash
t_check
=
19200
⋅
----------¹-----------
f _NVMBUS
A.3.1.2 Erase Verify Block (Blank Check) (FCMD=0x02)
The time required to perform a blank check is dependent on the location of the first non-blank word starting
at relative address zero. It takes one bus cycle per phrase to verify plus a setup of the command.
Assuming that no non-blank location is found, then the time to erase verify a P-Flash block is given by:
for 64 Kbyte P-Flash
t_pcheck
=
17200
⋅
----------¹-----------
f _NVMBUS
Assuming that no non-blank location is found, then the time to erase verify a D-Flash block is given by:
t_dcheck
=
2800
⋅
----------¹-----------
f _NVMBUS
MC9S12HY/HA-Family Reference Manual, Rev. 1.04
734
Freescale Semiconductor