73 lines
2.2 KiB
C
73 lines
2.2 KiB
C
#include "si5351.h"
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uint32_t si5351_freq_a;
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uint32_t si5351_freq_b;
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void si5351_init(uint32_t freq_xtal, uint32_t freq_a, uint32_t freq_b) {
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si5351_write8(CLK_ENABLE_CONTROL, 0x00); // Enable all outputs
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si5351_write8(XTAL_LOAD_CAP, 0xD2); //crystal load capacitor = 10pF
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si5351_write8(CLK0_CONTROL, 0x0F); // PLLA to CLK0, 8 mA output
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si5351_write8(PLL_RESET, 0xA0); // Reset both PLLs
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si5351_freq_a = freq_a;
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si5351_freq_b = freq_b;
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double fdiv = (double) si5351_freq_a / (double) freq_xtal;
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//TODO: Find better way to determine c and b
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uint32_t c = 0x0FFFFF;
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uint32_t a = (uint32_t) fdiv;
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double rm = fdiv - a;
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uint32_t b = rm * c;
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uint32_t p1 = 128 * a + (128 * b / c) - 512;
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uint32_t p2 = 128 * b - c * (128 * b / c);
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uint32_t p3 = c;
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si5351_write_params(PLL_A, p1, p2, p3);
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fdiv = (double) freq_xtal / (double) si5351_freq_a;
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//TODO: Find better way to determine c and b
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c = 0x0FFFFF;
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a = (uint32_t) fdiv;
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rm = fdiv - a;
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b = rm * c;
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p1 = 128 * a + (128 * b / c) - 512;
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p2 = 128 * b - c * (128 * b / c);
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p3 = c;
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si5351_write_params(PLL_B, p1, p2, p3);
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}
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void si5351_set_freq(enum si5351_param_base base, uint32_t freq) {
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//TODO: Pick freq by clock source
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double fdiv = (double) si5351_freq_a / (double) freq;
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//TODO: Find better way to determine c and b
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uint32_t c = 0x0FFFFF;
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uint32_t a = (uint32_t) fdiv;
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double rm = fdiv - a;
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uint32_t b = rm * c;
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uint32_t p1 = 128 * a + (128 * b / c) - 512;
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uint32_t p2 = 128 * b - c * (128 * b / c);
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uint32_t p3 = c;
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si5351_write_params(base, p1, p2, p3);
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}
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uint8_t si5351_write_params(enum si5351_param_base base, uint32_t p1, uint32_t p2, uint32_t p3) {
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uint8_t data[9] = {
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base,
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(p3 & 0x00FF00) >> 8,
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p3 & 0x0000FF,
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(p1 & 0x030000) >> 16,
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(p1 & 0x00FF00) >> 8,
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p1 & 0x0000FF,
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((p3 & 0x0F0000) >> 12) | ((p2 & 0x0F0000) >> 16),
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(p2 & 0x00FF00) >> 8,
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p2 & 0x0000FF
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};
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return twi_write(SI5351_ADDRESS, data, 9);
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}
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