M16C User Manual.pdf

Power controlMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTERPower controlThe following is a description of the three available power control modes:ModesPower control is available in three modes.(a) Normal operation mode• High-speed modeDivide-by-1 frequency of the main clock becomes the BCLK. The CPU operates with the internalclock selected. Each peripheral function operates according to its assigned clock.• Medium-speed modeDivide-by-2, divide-by-4, divide-by-8, or divide-by-16 frequency of the main clock becomes theBCLK. The CPU operates according to the internal clock selected. Each peripheral function operatesaccording to its assigned clock.• Low-speed modefC becomes the BCLK. The CPU operates according to the fc clock. The fc clock is supplied by thesecondary clock. Each peripheral function operates according to its assigned clock.• Low power consumption modeThe main clock operating in low-speed mode is stopped. The CPU operates according to the fCclock. The fc clock is supplied by the secondary clock. The only peripheral functions that operateare those with the sub-clock selected as the count source.(b) Wait modeThe CPU operation is stopped. The oscillators do not stop.(c) Stop modeAll oscillators stop. The CPU and all built-in peripheral functions stop. This mode, among the threemodes listed here, is the most effective in decreasing power consumption.Figure 1.13.5 is the state transition diagram of the above modes.48