Datasheet

FLASH Memory

Technical Data MC68HC908JB8•MC68HC08JB8•MC68HC08JT8 — Rev. 2.3

54 FLASH Memory Freescale Semiconductor

4.3 Functional Description

The FLASH memory consists of an array of 8,192 bytes for user memory

plus a small block of 16 bytes for user interrupt vectors. An erased bit

reads as logic 1 and a programmed bit reads as a logic 0. The FLASH

memory is block erasable. The minimum erase block size is 512 bytes.

Program and erase operation operations are facilitated through control

bits in FLASH control register (FLCR).The address ranges for the

FLASH memory are shown as follows:

• $DC00–$FBFF (user memory; 8,192 bytes)

• $FFF0–$FFFF (user interrupt vectors; 16 bytes)

Programming tools are available from Freescale. Contact your local

Freescale representative for more information.

NOTE: A security feature prevents viewing of the FLASH contents.

Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0

$FE08

FLASH Control Register

(FLCR)

HVEN MASS ERASE PGM

Write:

Reset:00000000

$FE09

FLASH Block Protect

(FLBPR)

Read:

BPR7 BPR6 BPR5 BPR4 BPR3 BPR2 BPR1 BPR0

Write:

Reset:00000000

Figure 4-1. FLASH Memory Register Summary

1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or

copying the FLASH difficult for unauthorized users.