HD6433640 HITACHI [Hitachi Semiconductor], HD6433640 Datasheet - Page 156

• Manufacturer Part Number: HD6433640
• Description: H8/3644 Series Hardware Manual
• Manufacturer: HITACHI [Hitachi Semiconductor]

Loop Counter and Watchdog Timer Overflow Interval Settings in Programs: The settings of
#a, #b, #c, #d, and #e in the program examples depend on the clock frequency. Sample loop
counter settings for typical operating frequencies are shown in table 6.12. The value of #e should
be set as indicated in table 6.13.
As software loops are used, there is intrinsic error, and the calculated value and actual time may
not be the same. Therefore, initial values should be set so that the total write time does not exceed
1 ms, and the total erase time does not exceed 30 s.
The maximum number of writes in the program examples is set as N = 6.
Write and erase operations as shown in the flowcharts are achieved by setting the values of #a, #b,
#c, and #d in the program examples as indicated in table 6.12. Use the settings shown in table 6.13
for the value of #e.
In these sample programs, wait state insertion is disabled. If wait states are used, the setting should
be made after the end of the program.
The set value for the watchdog timer (WDT) overflow time is calculated on the basis of the
number of instructions including the write time and erase time from the time the watchdog timer is
started until it stops. Therefore, no other instructions should be added between starting and
stopping of the watchdog timer in these programs.
Table 6.12 Set Values of #a, #b, #c, and #d for Typical Operating Frequencies when
Meaning of Variable
a (ø) Programming time
b (ø) tvs1
c (ø)
d (ø) Erase time (initial
(initial set value)
tvs2
set value)
Sample Program is Executed in On-Chip Memory (RAM)
Set Time
15.8 s
4 s
2 s
6.25 ms
f
ø = 8 MHz
Counter Set
Value
H'000F
H'06
H'03
H'0C34
OSC
= 16 MHz f
ø = 5 MHz
Counter Set
Value
H'0009
H'04
H'02
H'07A1
OSC
Oscillation Frequency
Operating Frequency
= 10 MHz f
ø = 4 MHz
Counter Set
Value
H'0007
H'03
H'01
H'061A
OSC
= 8 MHz
f
ø = 1 MHz
Counter Set
Value
H'0001
H'01
H'01
H'0186
OSC
= 2 MHz
147