MC68HC908GP32_08 Datasheet, PDF (39/266 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

NOTE
A security feature prevents viewing of the FLASH contents.⁽¹⁾
FLASH Memory
2.6.2 FLASH Control Register
The FLASH control register (FLCR) controls FLASH program and erase operations.
Address: $FE08
Bit 7
6
5
4
3
2
1
Bit 0
Read: 0
0
0
0
HVEN MASS ERASE PGM
Write:
Reset: 0
0
0
0
0
0
0
0
= Unimplemented
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 32Kbyte 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
2.6.3 FLASH Page Erase Operation
Use this step-by-step procedure to erase a page (128 bytes) of FLASH memory.
1. Set the ERASE bit, and clear the MASS bit in the FLASH control register.
2. Read the FLASH block protect register.
3. Write any data to any FLASH location within the page address range of the block to be erased.
4. Wait for a time, t_nvs (min. 10 µs)
5. Set the HVEN bit.
1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or copying the FLASH difficult for
unauthorized users.
MC68HC908GP32 Data Sheet, Rev. 10
Freescale Semiconductor
39