User`s manual

Engineering Bulletin

EB183 — Rev. 1.0

2 MOTOROLA

FLASH EEPROM Control Block

The FLASH EEPROM is controlled by a 4-byte register block, which is

located at address $00F4 upon reset. Within this block are four single-

byte registers:

• Lock control register (FEELCK)

• Module configuration register (FEEMCR)

• Module test register (FEETST)

• Module control register (FEECTL)

For more detail on these control registers, refer to Section 7.4 FLASH

EEPROM Registers of the

MC68HC912B32 Technical Summary

(Motorola order number MC68HC912B32TS/D). The sequence of how

to use these registers is covered later in this document.

FLASH EEPROM

Lock Control

The FEELCK register (located at $00F4) contains only the LOCK bit

(bit 0), which allows or prevents writing to the FEEMCR register. This

must be cleared in order to change the FEEMCR. Note that it is cleared

out of reset.

Address: $00F4

Bit 7 654321Bit 0

Read:

0000000LOCK

Write:

Reset:

00000000

Figure 1. FLASH EEPROM Lock Control Register (FEELCK)