HD6433644R datasheet(167/549 Pages) RENESAS

167 / 549 page

Section 6 ROM

Rev. 6.00 Sep 12, 2006 page 147 of 526

REJ09B0326-0600

Examples:

Sample calculations when executing a program in on-chip memory (RAM) at an operating

frequency of 6 MHz

a (

φ) =

9 = 10.8

≈ 10 = H'000A

b (

φ) =

× 4 = 4.8 ≈ 5 = H'05

c (

φ) =

× 2 = 2.4 ≈ 3 = H'03

d (

φ) =

× 1953 = 2343.6 ≈ 2343 = H'0927

Table 6.12 Watchdog Timer Overflow Interval Settings (Set Value of #e for Operating

Frequencies)

Oscillation Frequency

fOSC = 16 MHz

fOSC = 10 MHz

fOSC = 8 MHz

fOSC = 2 MHz

Operating Frequency

Variable

φφφφ = 8 MHz

φφφφ = 5 MHz

φφφφ = 4 MHz

φφφφ = 1 MHz

e (

φ)

H'9B

H'DF

H'E5

H'F7

6.7.7

Prewrite-Verify Mode

Prewrite-verify mode is a verify mode used to all bits to equalize their threshold voltages before

erasure.

To program all bits, write H'00 in accordance with the prewrite algorithm shown in figure 6.15.

Use this procedure to set all data in the flash memory to H'00 after programming. After the

necessary programming time has elapsed, exit program mode (by clearing the P bit to 0) and select

prewrite-verify mode (leave the P, E, PV, and EV bits all cleared to 0). In prewrite-verify mode, a

prewrite-verify voltage is applied to the memory cells at the read address. If the flash memory is

read in this state, the data at the read address will be read. After selecting prewrite-verify mode,

wait at least 4 µs before reading.

Note: For a sample prewriting program, see the prewrite subroutine in the sample erasing

program.

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