s908qc16vdse Freescale Semiconductor, Inc, s908qc16vdse Datasheet - Page 36

• Manufacturer Part Number: s908qc16vdse
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Memory
2.6 FLASH Memory (FLASH)
The FLASH memory is intended primarily for program storage. In-circuit programming allows the
operating program to be loaded into the FLASH memory after final assembly of the application product.
It is possible to program the entire array through the single-wire monitor mode interface. Because no
special voltages are needed for FLASH erase and programming operations, in-application programming
is also possible through other software-controlled communication paths.
This subsection describes the operation of the embedded FLASH memory. The FLASH memory can be
read, programmed, and erased from the internal V
enabled through the use of an internal charge pump.
The minimum size of FLASH memory that can be erased is 64 bytes; and the maximum size of FLASH
memory that can be programmed in a program cycle is 32 bytes (a row). Program and erase operations
are facilitated through control bits in the FLASH control register (FLCR). Details for these operations
appear later in this section.
2.6.1 FLASH Control Register
The FLASH control register (FLCR) controls FLASH program and erase operations.
HVEN — High Voltage Enable Bit
MASS — Mass Erase Control Bit
ERASE — Erase Control Bit
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1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or copying the FLASH difficult
This read/write bit enables high voltage from the charge pump to the memory for either program or
erase operation. It can only be set if either PGM =1 or ERASE =1 and the proper sequence for
program or erase is followed.
This read/write bit configures the memory for mass erase operation.
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.
for unauthorized users.
1 = High voltage enabled to array and charge pump on
0 = High voltage disabled to array and charge pump off
1 = Mass erase operation selected
0 = Mass erase operation unselected
1 = Erase operation selected
0 = Erase operation unselected
An erased bit reads as a 1 and a programmed bit reads as a 0. A security
feature prevents viewing of the FLASH contents.
Reset:
Read:
Write:
MC68HC908QC16 • MC68HC908QC8 • MC68HC908QC4 Data Sheet, Rev. 4
Bit 7
0
0
Figure 2-3. FLASH Control Register (FLCR)
= Unimplemented
6
0
0
5
0
0
NOTE
DD
4
0
0
supply. The program and erase operations are
HVEN
3
0
(1)
MASS
2
0
ERASE
1
0
Freescale Semiconductor
PGM
Bit 0
0