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nix-servo/fast-servo/pyfastservo/si5340.py

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# This file is part of Fast Servo Software Package.
#
# Copyright (C) 2023 Jakub Matyas
# Warsaw University of Technology <jakubk.m@gmail.com>
# SPDX-License-Identifier: GPL-3.0-or-later
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
# Additional Reference:
# https://github.com/torvalds/linux/blob/master/drivers/clk/clk-si5341.c
import time
from smbus2 import SMBus
BUS_NO = 0
IC_ADDR = 0x74
DEVICE_READY = 0x00FE
PLL_M_DEN = 0x023B
STATUS = 0x000C
STATUS_STICKY = 0x0011
STATUS_LOSREF = 0x04
STATUS_LOL = 0x08
def write_register(bus, address, value):
page = address >> 8
register = address & 0xFF
bus.write_byte_data(IC_ADDR, 0x01, page)
try:
bus.write_byte_data(IC_ADDR, register, value)
except Exception as e:
raise Exception(f"Write failed 0x{value:02X} at 0x{address:04X}: {e}")
def write_preamble(bus):
preamble = [
(0x0B24, 0xC0),
(0x0B25, 0x00),
(0x0502, 0x01),
(0x0505, 0x03),
(0x0957, 0x17),
(0x0B4E, 0x1A),
]
for address, value in preamble:
write_register(bus, address, value)
def write_postamble(bus):
postamble = [
(0x001C, 0x01), # Soft reset
(0x0B24, 0xC3),
(0x0B25, 0x02),
]
for address, value in postamble:
write_register(bus, address, value)
def wait_device_ready(bus):
for _ in range(15):
if bus.read_byte_data(IC_ADDR, DEVICE_READY) == 0x0F:
return True
time.sleep(0.02)
return False
def wait_for_lock(bus):
for _ in range(10):
status = bus.read_byte_data(IC_ADDR, STATUS)
if not (status & (STATUS_LOSREF | STATUS_LOL)):
return True
time.sleep(0.01)
return False
def check_pll_status(bus):
pll_status = bus.read_byte_data(IC_ADDR, 0x0C)
pll_locked = not (pll_status & STATUS_LOL)
print(f"PLL {'locked' if pll_locked else 'unlocked'}")
return pll_locked
def check_los_status(bus):
los_status = bus.read_byte_data(IC_ADDR, 0x0D)
xaxb_los = (los_status & 0x10) != 0
print(f"XA/XB LOS {'asserted' if xaxb_los else 'deasserted'}")
return not xaxb_los
def configure_si5340():
with SMBus(BUS_NO) as bus:
if not wait_device_ready(bus):
print("Device not ready. Aborting.")
return
# Programming sequence from ClockBuilder Pro, default settings
# to initialize system using XTAL input
main_config = [
(0x0006, 0x00), # TOOL_VERSION
(0x0007, 0x00), # Not in datasheet
(0x0008, 0x00), # Not in datasheet
(0x000B, 0x74), # I2C_ADDR
(0x0017, 0xD0), # INT mask (disable interrupts)
(0x0018, 0xFF), # INT mask
(0x0021, 0x0F), # Select XTAL as input
(0x0022, 0x00), # Not in datasheet
(0x002B, 0x02), # SPI config
(0x002C, 0x20), # LOS enable for XTAL
(0x002D, 0x00), # LOS timing
(0x002E, 0x00), # LOS trigger (thresholds)
(0x002F, 0x00),
(0x0030, 0x00),
(0x0031, 0x00),
(0x0032, 0x00),
(0x0033, 0x00),
(0x0034, 0x00),
(0x0035, 0x00), # LOS trigger (thresholds) end
(0x0036, 0x00), # LOS clear (thresholds)
(0x0037, 0x00),
(0x0038, 0x00),
(0x0039, 0x00),
(0x003A, 0x00),
(0x003B, 0x00),
(0x003C, 0x00),
(0x003D, 0x00), # LOS clear (thresholds) end
(0x0041, 0x00), # LOS0_DIV_SEL
(0x0042, 0x00), # LOS1_DIV_SEL
(0x0043, 0x00), # LOS2_DIV_SEL
(0x0044, 0x00), # LOS3_DIV_SEL
(0x009E, 0x00), # LOL_SET_THR
(0x0102, 0x01), # Enable outputs
(0x013F, 0x00), # OUTX_ALWAYS_ON
(0x0140, 0x00), # OUTX_ALWAYS_ON
(0x0141, 0x40), # OUT_DIS_LOL_MSK, OUT_DIS_MSK_LOS_PFD
(0x0202, 0x00), # XAXB_FREQ_OFFSET (=0)
# PLL Configuration
(0x0235, 0x00), # M_NUM
(0x0236, 0x00),
(0x0237, 0x00),
(0x0238, 0x80),
(0x0239, 0x89),
(0x023A, 0x00),
(0x023B, 0x00), # M_DEN
(0x023C, 0x00),
(0x023D, 0x00),
(0x023E, 0x80),
# Synthesizer configuration
(0x0302, 0x00), # N0_NUM
(0x0303, 0x00),
(0x0304, 0x00),
(0x0305, 0x00),
(0x0306, 0x21),
(0x0307, 0x00),
(0x0308, 0x00), # N0_DEN
(0x0309, 0x00),
(0x030A, 0x00),
(0x030B, 0x80),
(0x030C, 0x01), # N0_UPDATE
# N1 Configuration (1:1 ratio)
(0x030D, 0x00), # N1_NUM
(0x030E, 0x00),
(0x030F, 0x00),
(0x0310, 0x00),
(0x0311, 0x00),
(0x0312, 0x01),
(0x0313, 0x00), # N1_DEN
(0x0314, 0x00),
(0x0315, 0x00),
(0x0316, 0x01),
(0x0317, 0x01), # N1_UPDATE
# N2 Configuration (1:1 ratio)
(0x0318, 0x00), # N2_NUM
(0x0319, 0x00),
(0x031A, 0x00),
(0x031B, 0x00),
(0x031C, 0x00),
(0x031D, 0x01),
(0x031E, 0x00), # N2_DEN
(0x031F, 0x00),
(0x0320, 0x00),
(0x0321, 0x01),
(0x0322, 0x01), # N2_UPDATE
# N3 Configuration (1:1 ratio)
(0x0323, 0x00), # N3_NUM
(0x0324, 0x00),
(0x0325, 0x00),
(0x0326, 0x00),
(0x0327, 0x00),
(0x0328, 0x01),
(0x0329, 0x00), # N3_DEN
(0x032A, 0x00),
(0x032B, 0x00),
(0x032C, 0x01),
(0x032D, 0x01), # N3_UPDATE
# Output configuration
(0x0112, 0x06), # OUT0 config
(0x0113, 0x09), # OUT0 format
(0x0114, 0x3B), # OUT0 CM/AMPL
(0x0115, 0x28), # OUT0 MUX_SEL
(0x0117, 0x06), # OUT1 config
(0x0118, 0x09), # OUT1 format
(0x0119, 0x3B), # OUT1 CM/AMPL
(0x011A, 0x28), # OUT1 MUX_SEL
(0x0126, 0x06), # OUT2 config
(0x0127, 0x09), # OUT2 format
(0x0128, 0x3B), # OUT2 CM/AMPL
(0x0129, 0x28), # OUT2 MUX_SEL
(0x012B, 0x06), # OUT3 config
(0x012C, 0xCC), # OUT3 format
(0x012D, 0x00), # OUT3 CM/AMPL
(0x012E, 0x58), # OUT3 MUX_SEL
# Miscellaneous configuration
(0x090E, 0x02), # XAXB_EXTCLK_EN=0 XAXB_PDNB=1 (use XTAL)
(0x091C, 0x04), # ZDM_EN=4 (Normal mode)
(0x0943, 0x00), # IO_VDD_SEL
(0x0949, 0x00), # IN_EN (disable input clocks)
(0x094A, 0x00), # INx_TO_PFD_EN (disabled)
(0x094E, 0x49), # REFCLK_HYS_SEL (set by CBPro)
(0x094F, 0x02), # Not in datasheet
(0x095E, 0x00), # M_INTEGER (set by CBPro)
(0x0A02, 0x00), # N_ADD_0P5 (set by CBPro)
(0x0A03, 0x01), # N_CLK_TO_OUTX_EN
(0x0A04, 0x01), # N_PIBYP
(0x0A05, 0x01), # N_PDNB
(0x0A14, 0x00), # N0_HIGH_FREQ (set by CBPro)
(0x0A1A, 0x00), # N1_HIGH_FREQ (set by CBPro)
(0x0A20, 0x00), # N2_HIGH_FREQ (set by CBPro)
(0x0A26, 0x00), # N3_HIGH_FREQ (set by CBPro)
(0x0B44, 0x0F), # PDIV_ENB (set by CBPro)
(0x0B4A, 0x0E), # N_CLK_DIS
(0x0B57, 0x0E), # VCO_RESET_CALCODE (set by CBPro)
(0x0B58, 0x01), # VCO_RESET_CALCODE (set by CBPro)
]
write_preamble(bus)
time.sleep(0.3)
print("Writing main configuration...")
for address, value in main_config:
write_register(bus, address, value)
print("Main configuration written")
write_postamble(bus)
if not wait_for_lock(bus):
print("Error waiting for input clock or PLL lock")
else:
print("Input clock present and PLL locked")
bus.write_byte_data(IC_ADDR, STATUS_STICKY, 0)
# Final status check
pll_locked = check_pll_status(bus)
xaxb_signal_present = check_los_status(bus)
if not pll_locked:
print("Error: PLL is not locked")
elif not xaxb_signal_present:
print("Error: XA/XB signal is lost")
else:
print("Si5340 configuration completed successfully")
if __name__ == "__main__":
configure_si5340()
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