MC68HC908LB8_05 Datasheet, PDF (37/234 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

FLASH Memory (FLASH)
Programming tools are available from Freescale Semiconductor. Contact your local Freescale
Semiconductor representative for more information.
NOTE
A security feature prevents viewing of the FLASH contents.⁽¹⁾
2.6.1 FLASH Control Register
The FLASH control register (FLCR) controls FLASH program and erase operations.
Address:
Read:
Write:
Reset:
$FE08
Bit 7
0
0
6
5
0
0
0
0
= Unimplemented
4
3
2
1
Bit 0
0
HVEN
MASS ERASE
PGM
0
0
0
0
0
Figure 2-3. FLASH Control Register (FLCR)
HVEN — High-Voltage Enable Bit
This read/write bit enables the charge pump to drive high voltages for program and erase operations
in the array. HVEN can only be set if either PGM = 1 or ERASE = 1 and the proper sequence for
program or erase is followed.
1 = High voltage enabled to array and charge pump on
0 = High voltage disabled to array and charge pump off
MASS — Mass Erase Control Bit
Setting this read/write bit configures the 8-Kbyte FLASH array for mass erase operation.
1 = MASS erase operation selected
0 = PAGE erase operation selected
ERASE — Erase Control Bit
This read/write bit configures the memory for erase operation. ERASE is interlocked with the PGM bit
such that both bits cannot be equal to 1 or set to 1 at the same time.
1 = Erase operation selected
0 = Erase operation unselected
PGM — Program Control Bit
This read/write bit configures the memory for program operation. PGM is interlocked with the ERASE
bit such that both bits cannot be equal to 1 or set to 1 at the same time.
1 = Program operation selected
0 = Program operation unselected
2.6.2 FLASH Page Erase Operation
Use this step-by-step procedure to erase a page (64 bytes) of FLASH memory to read as logic 1. A page
consists of 64 consecutive bytes starting from addresses $XX00, $XX40, $XX80, or $XXC0. The 34-byte
user interrupt vectors area also forms a page. Any FLASH memory page can be erased alone, except for
the 34-byte interrupt vectors page, which must be mass erased.
1. No security feature is absolutely secure. However, Freescale Semiconductor’s strategy is to make reading or copying the
FLASH difficult for unauthorized users.
MC68HC908LB8 Data Sheet, Rev. 1
Freescale Semiconductor
37