Datasheet

Section 22 Flash Memory

Rev. 3.00 Sep. 28, 2009 Page 699 of 910

REJ09B0350-0300

(3) Flash Program/Erase Frequency Parameter (FPEFEQ: General Register ER0 of CPU)

FPEFEQ sets the operating frequency of the CPU. The operating frequency available in this LSI

ranges from 8 MHz to 20 MHz.

Bit Bit Name

Initial

Value

R/W Description

31 to 16 ⎯ ⎯ ⎯ Unused

These bits should be cleared to 0.

15 to 0 F15 to F0 ⎯ R/W Frequency Set

These bits set the operating frequency of the CPU. The

setting value must be calculated as follows:

1. Round off the operating frequency expressed in MHz

unit at the third decimal place to make it into two

decimal places.

2. Multiply the rounded number by 100 and convert the

result into binary and write it to FPEFEQ (general

For example, when the operating frequency of the CPU

is 20.000 MHz, the setting value is as follows:

1. Round 20.000 off at the third decimal place as

20.00.

2. Convert 20.00 × 100 = 2000 into a binary number

and set B'0000 0111 1101 0000 (H'07D0) in ER0.