def writeClock(freq_mult, divisor): i2c = busio.I2C(board.SCL, board.SDA) # Initialize SI5351. si5351 = adafruit_si5351.SI5351(i2c) si5351.pll_a.configure_integer(freq_mult) print('PLL A frequency: {0}mhz'.format(si5351.pll_a.frequency/1000000)) # si5351.pll_b.configure_fractional(24, 2, 3) # Multiply 25mhz by 24.667 (24 2/3) # print('PLL B frequency: {0}mhz'.format(si5351.pll_b.frequency/1000000)) si5351.clock_0.configure_integer(si5351.pll_a, divisor) print('Clock 0: {0}mhz'.format(si5351.clock_0.frequency/1000000)) # si5351.clock_1.configure_fractional(si5351.pll_b, 45, 1, 2) # Divide by 45.5 (45 1/2) # print('Clock 1: {0}mhz'.format(si5351.clock_1.frequency/1000000)) # si5351.clock_2.configure_integer(si5351.pll_b, 900) # si5351.clock_2.r_divider = adafruit_si5351.R_DIV_64 # print('Clock 2: {0}khz'.format(si5351.clock_2.frequency/1000)) # After configuring PLLs and clocks, enable the outputs. si5351.outputs_enabled = True
# - PLL B at 616.66667mhz # - Clock 0 at 112.5mhz, using PLL A as a source divided by 8 # - Clock 1 at 13.553115mhz, using PLL B as a source divided by 45.5 # - Clock 2 at 10.76khz, using PLL B as a source divided by 900 and further # divided with an R divider of 64. import board import busio import adafruit_si5351 # Initialize I2C bus. i2c = busio.I2C(board.SCL, board.SDA) # Initialize SI5351. si5351 = adafruit_si5351.SI5351(i2c) # Alternatively you can specify the I2C address if it has been changed: # si5351 = adafruit_si5351.SI5351(i2c, address=0x61) # Now configue the PLLs and clock outputs. # The PLLs can be configured with a multiplier and division of the on-board # 25mhz reference crystal. For example configure PLL A to 900mhz by multiplying # by 36. This uses an integer multiplier which is more accurate over time # but allows less of a range of frequencies compared to a fractional # multiplier shown next. si5351.pll_a.configure_integer(36) # Multiply 25mhz by 36 print("PLL A frequency: {0}mhz".format(si5351.pll_a.frequency / 1000000)) # And next configure PLL B to 616.6667mhz by multiplying 25mhz by 24.667 using # the fractional multiplier configuration. Notice you specify the integer # multiplier and then a numerator and denominator as separate values, i.e.