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27 lines
682 B
27 lines
682 B
1 year ago
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#include <stdint.h>
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#include "clock.h"
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static struct prci_mem_map *const prci_mm = (struct prci_mem_map *const)PRCI_MEMORY_BLOCK;
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// Sets the hfpclkpll register to the appropriate value for the freqency, returns
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// -1 on error
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// TODO: for higher frequencies use the internal PLLs
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int set_hfp_frequency(uint32_t f)
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{
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// test if the correct register is present
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if (!prci_mm->prci_plls.hfpclkpll)
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return -1;
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// make sure that the clock source is set to external
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prci_mm->hfpclkpllsel = 1;
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// the external clock source is 26MHz, the formula for the baud rate is:
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// f_baud = f_hfclk / (1 + hfpclk_div_reg)
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prci_mm->hfpclk_div_reg = (HFCLK_FREQ_HZ/f + 1);
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return 0;
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}
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