mc9s08gt16a Freescale Semiconductor, Inc, mc9s08gt16a Datasheet - Page 49

• Manufacturer Part Number: mc9s08gt16a
• Description: Hcs08 Microcontrollers 8-bit Microcontroller Family
• Manufacturer: Freescale Semiconductor, Inc

4.4.2
Before any program or erase command can be accepted, the FLASH clock divider register (FCDIV) must
be written to set the internal clock for the FLASH module to a frequency (f
200 kHz (see
reset initialization. FCDIV cannot be written if the access error flag, FACCERR in FSTAT, is set. The user
must ensure that FACCERR is not set before writing to the FCDIV register. One period of the resulting
clock (1/f
of these timing pulses is used by the command processor to complete a program or erase command.
Table 4-5
of FCLK (f
of cycles of FCLK and as an absolute time for the case where t
shown include overhead for the command state machine and enabling and disabling of program and erase
voltages.
4.4.3
The steps for executing any of the commands are listed below. The FCDIV register must be initialized and
any error flags cleared before beginning command execution. The command execution steps are:
Freescale Semiconductor
•
•
•
1. Write a data value to an address in the FLASH array. The address and data information from this
Flexible block protection
Security feature for FLASH and RAM
Auto power-down for low-frequency read accesses
write is latched into the FLASH interface. This write is a required first step in any command
sequence. For erase and blank check commands, the value of the data is not important. For page
erase commands, the address may be any address in the 512-byte page of FLASH to be erased. For
mass erase and blank check commands, the address can be any address in the FLASH memory.
Whole pages of 512 bytes are the smallest blocks of FLASH that may be erased.
FCLK
shows program and erase times. The bus clock frequency and FCDIV determine the frequency
Program and Erase Times
FCLK
Program and Erase Command Execution
1
Table
Byte program
Byte program (burst)
Page erase
Mass erase
) is used by the command processor to time program and erase pulses. An integer number
Excluding start/end overhead
). The time for one cycle of FCLK is t
4.6.1). This register can be written only once, so normally this write is done during
Parameter
Table 4-5. Program and Erase Times
MC9S08GT16A/GT8A Data Sheet, Rev. 1
Cycles of FCLK
20,000
4000
9
4
FCLK
= 1/f
FCLK
FCLK
Time if FCLK = 200 kHz
= 5 µs. Program and erase times
. The times are shown as a number
FCLK
100 ms
20 µs
20 ms
45 µs
) between 150 kHz and
1
Memory
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