Hello, I am using RL78 F14 micro controller and I have 20 Mhz quartz connected as main clock source on the board. Now I need to set the clock frequency for CPU which should be 32 Mhz and clock source for Controller Area Network interface. CPU Clock Frequency (Required = 32 Mhz) 1) From the document I understood I cannot use PLL to create 32 Mhz and I have to go for Internal On - Chip Oscillator to use 32 Mhz CAN Clock Frequency I get the information from Pg1300 of RL78 F14 User Manual to set the DCS bit of GCFGL register. It says like this - When this bit is set to 0, the clock obtained by frequency-dividing fCLK by 2 (fCLK/2) is used as the clock source of the CAN clock (fCAN). When this bit is set to 1, the X1 clock (fx) is used as the clock source of the CAN clock. If the X1 clock (fx) is selected, make the X1 clock (fx) into the value below halfNote1, 2 of fCLK. Notes 1. When the fCLK clock source is high-speed on-chip oscillator or PLL clock sourced high-speed on-chip oscillator, the frequency must be set as “fX fCLK/2”. 2. If the high-speed system clock is to be selected as fCLK, do not select fX as fCAN. I am little bit confused from the note 1. Can it be that I cannot use Internal clock for CPU and external fx which is 20 Mhz as clock source for CAN. Can anyone comment over it? Thanks Ecstud
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