HD64F3039F18 Datasheet, PDF (530/710 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8 Family / H8/300H Series

Section 16 Clock Pulse Generator
16.5.3 Usage Notes
The DIVCR setting changes the φ frequency, so note the following points.
• Select a frequency division ratio that stays within the assured operation range specified for the
clock cycle time t_cyc in the AC electrical characteristics. Note that φ_MIN = 1 MHz. Avoid settings
that give system clock frequencies less than 1 MHz.
All on-chip module operations are based on φ. Note that the timing of timer operations, serial
communication, and other time-dependent processing differs before and after any change in the
division ratio. The waiting time for exit from software standby mode also changes when the
division ratio is changed. For details, see section 17.4.3, Selection of Oscillator Waiting Time after
Exit from Software Standby Mode
Rev.3.00 Mar. 26, 2007 Page 506 of 682
REJ09B0353-0300