hd64338342hw Renesas Electronics Corporation., hd64338342hw Datasheet - Page 310

• Manufacturer Part Number: hd64338342hw
• Description: Renesas 8-bit Single-chip Microcomputer H8 Family/h8/300l Super Low Power Series
• Manufacturer: Renesas Electronics Corporation.

Section 9 Timers
9.3.5
Note the following regarding the operation of timer C.
(1) Counting errors caused by external event input
Rev. 6.00 Aug 04, 2006 page 274 of 680
REJ09B0145-0600
Timer counter errors may occur under the following conditions.
Conditions
•
Symptom
•
Approximate rate of occurrence
The symptom described is caused by the internal circuit configuration of the device and
therefore difficult to avoid. Therefore, it is not advisable to use the clock counter for
applications requiring a high degree of accuracy.
An external event (TMIC) is used in subsleep mode.
The counter increments or decrements twice for a single external event input.
The approximate rate of occurrence in cases where the external event input is not
synchronized with internal operation is defined by the following equation.
For example, if tsubcyc = 61.06 µs (subclock w/2), P = 0.0005 (0.05%). If 2,000 external
event inputs occur, there is a likelihood that one of them will cause the counter to
increment or decrement twice (+2 or –2).
Usage Note
Approximate rate of occurrence P = 30 ns / tsubcyc