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Chapter 13 Clock Control
7.Q & A
7.4 How do I set the operation clock division ratios?

CPU clock setting

The CPU clock setting is set using the CLKB division ratio selection bits (DIVR0.B[3:0]).

Peripheral clock setting

The peripheral clock setting is set using the CLKP division ratio selection bits (DIVR0.P[3:0]).

Setting for the external bus clock

The setting for the external bus clock is set using the CLKT division ratio selection bits (DIVR1.T[3:0]).
PLL multiplier ratio CLKB division ratio selection
bits(B[3:0])
Example frequency
When FΦ= 32MHz When FΦ= 16MHz
To select no division Set to “0000”. FCLKB = 32.0MHz FCLKB = 16.0MHz
To select divide by 2 Set to “0001”. FCLKB = 16.0MHz FCLKB = 8.00MHz
To select divide by 3 Set to “0010”. FCLKB = 10.6MHz FCLKB = 5.33MHz
To select divide by 4 Set to “0011”. FCLKB = 8.00MHz FCLKB = 4.00MHz
To select divide by 5 Set to “0100”. FCLKB = 6.40MHz FCLKB = 3.20MHz
To select divide by 6 Set to “0101”. FCLKB = 5.33MHz FCLKB = 2.66MHz
To select divide by 7 Set to “0110”. FCLKB = 4.57MHz FCLKB = 2.28MHz
To select divide by 8 Set to “0111”. FCLKB = 4.00MHz FCLKB = 2.00MHz
To select divide by 16 Set to “1111”. FCLKB = 2.00MHz FCLKB = 1.00MHz
PLL multiplier ratio CLKP division ratio selection bits
(P[3:0])
Example frequency
When FΦ = 32MHz When FΦ = 16MHz
To select no division Set to “0000”. FCLKP = 32.0MHz FCLKP = 16.0MHz
To select divide by 2 Set to “0001”. FCLKP = 16.0MHz FCLKP = 8.00MHz
To select divide by 3 Set to “0010”. FCLKP = 10.6MHz FCLKP = 5.33MHz
To select divide by 4 Set to “0011”. FCLKP = 8.00MHz FCLKP = 4.00MHz
To select divide by 5 Set to “0100”. FCLKP = 6.40MHz FCLKP = 3.20MHz
To select divide by 6 Set to “0101”. FCLKP = 5.33MHz FCLKP = 2.66MHz
To select divide by 7 Set to “0110”. FCLKP = 4.57MHz FCLKP = 2.28MHz
To select divide by 8 Set to “0111”. FCLKP = 4.00MHz FCLKP = 2.00MHz
To select divide by 16 Set to “1111”. FCLKP = 2.00MHz FCLKP = 1.00MHz
PLL multiplier ratio CLKT division ratio selection bits
(T[3:0])
Example frequency
When FΦ = 32MHz When FΦ = 16MHz
To select no division Set to “0000”. FCLKT = 32.0MHz FCLKT = 16.0MHz
To select divide by 2 Set to “0001”. FCLKT = 16.0MHz FCLKT = 8.00MHz
To select divide by 3 Set to “0010”. FCLKT = 10.6MHz FCLKT = 5.33MHz
To select divide by 4 Set to “0011”. FCLKT = 8.00MHz FCLKT = 4.00MHz
To select divide by 5 Set to “0100”. FCLKT = 6.40MHz FCLKT = 3.20MHz
To select divide by 6 Set to “0101”. FCLKT = 5.33MHz FCLKT = 2.66MHz
To select divide by 7 Set to “0110”. FCLKT = 4.57MHz FCLKT = 2.28MHz
To select divide by 8 Set to “0111”. FCLKT = 4.00MHz FCLKT = 2.00MHz
To select divide by 16 Set to “1111”. FCLKT = 2.00MHz FCLKT = 1.00MHz