MC68HC908JK1 Datasheet, PDF (40/210 Pages) Motorola, Inc – MC68HC908JK1

FLASH Memory (FLASH)
4.3 Functional Description
The FLASH memory consists of an array of 4096 or 1536 bytes with an
additional 48 bytes for user vectors. 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. The address ranges for the user memory and vectors are:
• $EC00 – $FBFF; user memory, 4096 bytes:
MC68H(R)C908JL3/JK3
• $F600 – $FBFF; user memory, 1536 bytes: MC68H(R)C908JK1
• $FFD0 – $FFFF; user interrupt vectors, 48 bytes.
NOTE: An erased bit reads as logic 1 and a programmed bit reads as logic 0.
A security feature prevents viewing of the FLASH contents.¹
4.4 FLASH Control Register
The FLASH Control Register 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
Figure 4-1. FLASH Control Register (FLCR)
HVEN — High Voltage Enable Bit
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.
1. No security feature is absolutely secure. However, Motorola’s strategy is to make reading or
copying the FLASH difficult for unauthorized users.
Technical Data
40
FLASH Memory (FLASH)
MC68H(R)C908JL3 — Rev. 1.0
MOTOROLA