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artiq
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artiq/artiq/firmware/libboard_artiq/wrpll.rs

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use board_misoc::{csr, clock};
mod i2c {
use board_misoc::{csr, clock};
#[derive(Debug, Clone, Copy)]
pub enum Dcxo {
Main,
Helper
}
fn half_period() { clock::spin_us(1) }
const SDA_MASK: u8 = 2;
const SCL_MASK: u8 = 1;
fn sda_i(dcxo: Dcxo) -> bool {
let reg = match dcxo {
Dcxo::Main => unsafe { csr::wrpll::main_dcxo_gpio_in_read() },
Dcxo::Helper => unsafe { csr::wrpll::helper_dcxo_gpio_in_read() },
};
reg & SDA_MASK != 0
}
fn sda_oe(dcxo: Dcxo, oe: bool) {
let reg = match dcxo {
Dcxo::Main => unsafe { csr::wrpll::main_dcxo_gpio_oe_read() },
Dcxo::Helper => unsafe { csr::wrpll::helper_dcxo_gpio_oe_read() },
};
let reg = if oe { reg | SDA_MASK } else { reg & !SDA_MASK };
match dcxo {
Dcxo::Main => unsafe { csr::wrpll::main_dcxo_gpio_oe_write(reg) },
Dcxo::Helper => unsafe { csr::wrpll::helper_dcxo_gpio_oe_write(reg) }
}
}
fn sda_o(dcxo: Dcxo, o: bool) {
let reg = match dcxo {
Dcxo::Main => unsafe { csr::wrpll::main_dcxo_gpio_out_read() },
Dcxo::Helper => unsafe { csr::wrpll::helper_dcxo_gpio_out_read() },
};
let reg = if o { reg | SDA_MASK } else { reg & !SDA_MASK };
match dcxo {
Dcxo::Main => unsafe { csr::wrpll::main_dcxo_gpio_out_write(reg) },
Dcxo::Helper => unsafe { csr::wrpll::helper_dcxo_gpio_out_write(reg) }
}
}
fn scl_oe(dcxo: Dcxo, oe: bool) {
let reg = match dcxo {
Dcxo::Main => unsafe { csr::wrpll::main_dcxo_gpio_oe_read() },
Dcxo::Helper => unsafe { csr::wrpll::helper_dcxo_gpio_oe_read() },
};
let reg = if oe { reg | SCL_MASK } else { reg & !SCL_MASK };
match dcxo {
Dcxo::Main => unsafe { csr::wrpll::main_dcxo_gpio_oe_write(reg) },
Dcxo::Helper => unsafe { csr::wrpll::helper_dcxo_gpio_oe_write(reg) }
}
}
fn scl_o(dcxo: Dcxo, o: bool) {
let reg = match dcxo {
Dcxo::Main => unsafe { csr::wrpll::main_dcxo_gpio_out_read() },
Dcxo::Helper => unsafe { csr::wrpll::helper_dcxo_gpio_out_read() },
};
let reg = if o { reg | SCL_MASK } else { reg & !SCL_MASK };
match dcxo {
Dcxo::Main => unsafe { csr::wrpll::main_dcxo_gpio_out_write(reg) },
Dcxo::Helper => unsafe { csr::wrpll::helper_dcxo_gpio_out_write(reg) }
}
}
pub fn init(dcxo: Dcxo) -> Result<(), &'static str> {
// Set SCL as output, and high level
scl_o(dcxo, true);
scl_oe(dcxo, true);
// Prepare a zero level on SDA so that sda_oe pulls it down
sda_o(dcxo, false);
// Release SDA
sda_oe(dcxo, false);
// Check the I2C bus is ready
half_period();
half_period();
if !sda_i(dcxo) {
// Try toggling SCL a few times
for _bit in 0..8 {
scl_o(dcxo, false);
half_period();
scl_o(dcxo, true);
half_period();
}
}
if !sda_i(dcxo) {
return Err("SDA is stuck low and doesn't get unstuck");
}
Ok(())
}
pub fn start(dcxo: Dcxo) {
// Set SCL high then SDA low
scl_o(dcxo, true);
half_period();
sda_oe(dcxo, true);
half_period();
}
pub fn stop(dcxo: Dcxo) {
// First, make sure SCL is low, so that the target releases the SDA line
scl_o(dcxo, false);
half_period();
// Set SCL high then SDA high
sda_oe(dcxo, true);
scl_o(dcxo, true);
half_period();
sda_oe(dcxo, false);
half_period();
}
pub fn write(dcxo: Dcxo, data: u8) -> bool {
// MSB first
for bit in (0..8).rev() {
// Set SCL low and set our bit on SDA
scl_o(dcxo, false);
sda_oe(dcxo, data & (1 << bit) == 0);
half_period();
// Set SCL high ; data is shifted on the rising edge of SCL
scl_o(dcxo, true);
half_period();
}
// Check ack
// Set SCL low, then release SDA so that the I2C target can respond
scl_o(dcxo, false);
half_period();
sda_oe(dcxo, false);
// Set SCL high and check for ack
scl_o(dcxo, true);
half_period();
// returns true if acked (I2C target pulled SDA low)
!sda_i(dcxo)
}
pub fn read(dcxo: Dcxo, ack: bool) -> u8 {
// Set SCL low first, otherwise setting SDA as input may cause a transition
// on SDA with SCL high which will be interpreted as START/STOP condition.
scl_o(dcxo, false);
half_period(); // make sure SCL has settled low
sda_oe(dcxo, false);
let mut data: u8 = 0;
// MSB first
for bit in (0..8).rev() {
scl_o(dcxo, false);
half_period();
// Set SCL high and shift data
scl_o(dcxo, true);
half_period();
if sda_i(dcxo) { data |= 1 << bit }
}
// Send ack
// Set SCL low and pull SDA low when acking
scl_o(dcxo, false);
if ack { sda_oe(dcxo, true) }
half_period();
// then set SCL high
scl_o(dcxo, true);
half_period();
data
}
}
mod si549 {
use board_misoc::clock;
use super::i2c;
#[cfg(soc_platform = "kasli")]
pub const ADDRESS: u8 = 0x67;
pub fn write(dcxo: i2c::Dcxo, reg: u8, val: u8) -> Result<(), &'static str> {
i2c::start(dcxo);
if !i2c::write(dcxo, ADDRESS << 1) {
return Err("Si549 failed to ack write address")
}
if !i2c::write(dcxo, reg) {
return Err("Si549 failed to ack register")
}
if !i2c::write(dcxo, val) {
return Err("Si549 failed to ack value")
}
i2c::stop(dcxo);
Ok(())
}
pub fn write_no_ack_value(dcxo: i2c::Dcxo, reg: u8, val: u8) -> Result<(), &'static str> {
i2c::start(dcxo);
if !i2c::write(dcxo, ADDRESS << 1) {
return Err("Si549 failed to ack write address")
}
if !i2c::write(dcxo, reg) {
return Err("Si549 failed to ack register")
}
i2c::write(dcxo, val);
i2c::stop(dcxo);
Ok(())
}
pub fn read(dcxo: i2c::Dcxo, reg: u8) -> Result<u8, &'static str> {
i2c::start(dcxo);
if !i2c::write(dcxo, ADDRESS << 1) {
return Err("Si549 failed to ack write address")
}
if !i2c::write(dcxo, reg) {
return Err("Si549 failed to ack register")
}
i2c::stop(dcxo);
i2c::start(dcxo);
if !i2c::write(dcxo, (ADDRESS << 1) | 1) {
return Err("Si549 failed to ack read address")
}
let val = i2c::read(dcxo, false);
i2c::stop(dcxo);
Ok(val)
}
pub fn program(dcxo: i2c::Dcxo, hsdiv: u16, lsdiv: u8, fbdiv: u64) -> Result<(), &'static str> {
i2c::init(dcxo)?;
write(dcxo, 255, 0x00)?; // PAGE
write_no_ack_value(dcxo, 7, 0x80)?; // RESET
clock::spin_us(100_000); // required? not specified in datasheet.
write(dcxo, 255, 0x00)?; // PAGE
write(dcxo, 69, 0x00)?; // Disable FCAL override.
// Note: Value 0x00 from Table 5.6 is inconsistent with Table 5.7,
// which shows bit 0 as reserved and =1.
write(dcxo, 17, 0x00)?; // Synchronously disable output
// The Si549 has no ID register, so we check that it responds correctly
// by writing values to a RAM-like register and reading them back.
for test_value in 0..255 {
write(dcxo, 23, test_value)?;
let readback = read(dcxo, 23)?;
if readback != test_value {
return Err("Si549 detection failed");
}
}
write(dcxo, 23, hsdiv as u8)?;
write(dcxo, 24, (hsdiv >> 8) as u8 | (lsdiv << 4))?;
write(dcxo, 26, fbdiv as u8)?;
write(dcxo, 27, (fbdiv >> 8) as u8)?;
write(dcxo, 28, (fbdiv >> 16) as u8)?;
write(dcxo, 29, (fbdiv >> 24) as u8)?;
write(dcxo, 30, (fbdiv >> 32) as u8)?;
write(dcxo, 31, (fbdiv >> 40) as u8)?;
write(dcxo, 7, 0x08)?; // Start FCAL
write(dcxo, 17, 0x01)?; // Synchronously enable output
Ok(())
}
// Si549 digital frequency trim ("all-digital PLL" register)
// ∆ f_out = adpll * 0.0001164e-6 (0.1164 ppb/lsb)
// max trim range is +- 950 ppm
pub fn set_adpll(dcxo: i2c::Dcxo, adpll: i32) -> Result<(), &'static str> {
write(dcxo, 231, adpll as u8)?;
write(dcxo, 232, (adpll >> 8) as u8)?;
write(dcxo, 233, (adpll >> 16) as u8)?;
clock::spin_us(100);
Ok(())
}
pub fn get_adpll(dcxo: i2c::Dcxo) -> Result<i32, &'static str> {
let b1 = read(dcxo, 231)? as i32;
let b2 = read(dcxo, 232)? as i32;
let b3 = read(dcxo, 233)? as i8 as i32;
Ok(b3 << 16 | b2 << 8 | b1)
}
}
// to do: load from gateware config
const DDMTD_COUNTER_N: u32 = 15;
const DDMTD_COUNTER_M: u32 = (1 << DDMTD_COUNTER_N);
const F_SYS: f64 = csr::CONFIG_CLOCK_FREQUENCY as f64;
const F_MAIN: f64 = 125.0e6;
const F_HELPER: f64 = F_MAIN * DDMTD_COUNTER_M as f64 / (DDMTD_COUNTER_M + 1) as f64;
const F_BEAT: f64 = F_MAIN - F_HELPER;
const TIME_STEP: f32 = 1./F_BEAT as f32;
fn ddmtd_tag_to_s(mu: f32) -> f32 {
return (mu as f32)*TIME_STEP;
}
fn get_frequencies() -> (u32, u32, u32) {
unsafe {
csr::wrpll::frequency_counter_update_en_write(1);
// wait for at least one full update cycle (> 2 timer periods)
clock::spin_us(200_000);
csr::wrpll::frequency_counter_update_en_write(0);
let helper = csr::wrpll::frequency_counter_counter_helper_read();
let main = csr::wrpll::frequency_counter_counter_rtio_read();
let cdr = csr::wrpll::frequency_counter_counter_rtio_rx0_read();
(helper, main, cdr)
}
}
fn log_frequencies() -> (u32, u32, u32) {
let (f_helper, f_main, f_cdr) = get_frequencies();
let conv_khz = |f| 4*(f as u64)*(csr::CONFIG_CLOCK_FREQUENCY as u64)/(1000*(1 << 23));
info!("helper clock frequency: {}kHz ({})", conv_khz(f_helper), f_helper);
info!("main clock frequency: {}kHz ({})", conv_khz(f_main), f_main);
info!("CDR clock frequency: {}kHz ({})", conv_khz(f_cdr), f_cdr);
(f_helper, f_main, f_cdr)
}
fn get_tags() -> (i32, i32, u16, u16) {
unsafe {
csr::wrpll::tag_arm_write(1);
while csr::wrpll::tag_arm_read() != 0 {}
let main_diff = csr::wrpll::main_diff_tag_read() as i32;
let helper_diff = csr::wrpll::helper_diff_tag_read() as i32;
let ref_tag = csr::wrpll::ref_tag_read();
let main_tag = csr::wrpll::main_tag_read();
(main_diff, helper_diff, ref_tag, main_tag)
}
}
fn print_tags() {
const NUM_TAGS: usize = 30;
let mut main_diffs = [0; NUM_TAGS]; // input to main loop filter
let mut helper_diffs = [0; NUM_TAGS]; // input to helper loop filter
let mut ref_tags = [0; NUM_TAGS];
let mut main_tags = [0; NUM_TAGS];
let mut jitter = [0 as f32; NUM_TAGS];
for i in 0..NUM_TAGS {
let (main_diff, helper_diff, ref_tag, main_tag) = get_tags();
main_diffs[i] = main_diff;
helper_diffs[i] = helper_diff;
ref_tags[i] = ref_tag;
main_tags[i] = main_tag;
}
info!("DDMTD ref tags: {:?}", ref_tags);
info!("DDMTD main tags: {:?}", main_tags);
info!("DDMTD main diffs: {:?}", main_diffs);
info!("DDMTD helper diffs: {:?}", helper_diffs);
// look at the difference between the main DCXO and reference...
let t0 = main_diffs[0];
main_diffs.iter_mut().for_each(|x| *x -= t0);
// crude estimate of the max difference across our sample set (assumes no unwrapping issues...)
let delta = main_diffs[main_diffs.len()-1] as f32 / (main_diffs.len()-1) as f32;
info!("detla: {:?} tags", delta);
let delta_f: f32 = delta/DDMTD_COUNTER_M as f32 * F_BEAT as f32;
info!("MAIN <-> ref frequency difference: {:?} Hz ({:?} ppm)", delta_f, delta_f/F_HELPER as f32 * 1e6);
jitter.iter_mut().enumerate().for_each(|(i, x)| *x = main_diffs[i] as f32 - delta*(i as f32));
info!("jitter: {:?} tags", jitter);
let var = jitter.iter().map(|x| x*x).fold(0 as f32, |acc, x| acc + x as f32) / NUM_TAGS as f32;
info!("variance: {:?} tags^2", var);
}
pub fn init() {
info!("initializing WR PLL...");
unsafe { csr::wrpll::helper_reset_write(1); }
unsafe {
csr::wrpll::helper_dcxo_i2c_address_write(si549::ADDRESS);
csr::wrpll::main_dcxo_i2c_address_write(si549::ADDRESS);
}
#[cfg(rtio_frequency = "125.0")]
let (h_hsdiv, h_lsdiv, h_fbdiv) = (0x05c, 0, 0x04b5badb98a);
#[cfg(rtio_frequency = "125.0")]
let (m_hsdiv, m_lsdiv, m_fbdiv) = (0x05c, 0, 0x04b5c447213);
si549::program(i2c::Dcxo::Main, m_hsdiv, m_lsdiv, m_fbdiv)
.expect("cannot initialize main Si549");
si549::program(i2c::Dcxo::Helper, h_hsdiv, h_lsdiv, h_fbdiv)
.expect("cannot initialize helper Si549");
// Si549 Settling Time for Large Frequency Change.
// Datasheet said 10ms but it lied.
clock::spin_us(50_000);
unsafe { csr::wrpll::helper_reset_write(0); }
clock::spin_us(1);
}
pub fn diagnostics() {
info!("WRPLL diagnostics...");
info!("Untrimmed oscillator frequencies:");
log_frequencies();
info!("Increase helper DCXO frequency by +10ppm (1.25kHz):");
si549::set_adpll(i2c::Dcxo::Helper, 85911).expect("ADPLL write failed");
// to do: add check on frequency?
log_frequencies();
}
fn trim_dcxos(f_helper: u32, f_main: u32, f_cdr: u32) -> Result<(i32, i32), &'static str> {
info!("Trimming oscillator frequencies...");
const DCXO_STEP: i64 = (1.0e6/0.0001164) as i64;
const ADPLL_MAX: i64 = (950.0/0.0001164) as i64;
const TIMER_WIDTH: u32 = 23;
const COUNTER_DIV: u32 = 2;
// how many counts we expect to measure
const SYS_COUNTS: i64 = (1 << (TIMER_WIDTH - COUNTER_DIV)) as i64;
const EXP_MAIN_COUNTS: i64 = ((SYS_COUNTS as f64) * (F_MAIN/F_SYS)) as i64;
const EXP_HELPER_COUNTS: i64 = ((SYS_COUNTS as f64) * (F_HELPER/F_SYS)) as i64;
// calibrate the SYS clock to the CDR clock and correct the measured counts
// assume frequency errors are small so we can make an additive correction
// positive error means sys clock is too fast
let sys_err: i64 = EXP_MAIN_COUNTS - (f_cdr as i64);
let main_err: i64 = EXP_MAIN_COUNTS - (f_main as i64) - sys_err;
let helper_err: i64 = EXP_HELPER_COUNTS - (f_helper as i64) - sys_err;
info!("sys count err {}", sys_err);
info!("main counts err {}", main_err);
info!("helper counts err {}", helper_err);
// calculate required adjustment to the ADPLL register see
// https://www.silabs.com/documents/public/data-sheets/si549-datasheet.pdf
// section 5.6
let helper_adpll: i64 = helper_err*DCXO_STEP/EXP_HELPER_COUNTS;
let main_adpll: i64 = main_err*DCXO_STEP/EXP_MAIN_COUNTS;
if helper_adpll.abs() > ADPLL_MAX {
return Err("helper DCXO offset too large");
}
if main_adpll.abs() > ADPLL_MAX {
return Err("main DCXO offset too large");
}
info!("ADPLL offsets: helper={} main={}", helper_adpll, main_adpll);
Ok((helper_adpll as i32, main_adpll as i32))
}
fn statistics(data: &[u16]) -> (f32, f32) {
let sum = data.iter().fold(0 as u32, |acc, x| acc + *x as u32);
let mean = sum as f32 / data.len() as f32;
let squared_sum = data.iter().fold(0 as u32, |acc, x| acc + (*x as u32).pow(2));
let variance = (squared_sum as f32 / data.len() as f32) - mean;
return (mean, variance)
}
fn select_recovered_clock_int(rc: bool) -> Result<(), &'static str> {
info!("Untrimmed oscillator frequencies:");
let (f_helper, f_main, f_cdr) = log_frequencies();
if rc {
let (helper_adpll, main_adpll) = trim_dcxos(f_helper, f_main, f_cdr)?;
// to do: add assertion on max frequency shift here?
si549::set_adpll(i2c::Dcxo::Helper, helper_adpll).expect("ADPLL write failed");
si549::set_adpll(i2c::Dcxo::Main, main_adpll).expect("ADPLL write failed");
log_frequencies();
clock::spin_us(100_000); // TO DO: remove/reduce!
print_tags();
info!("increasing main DCXO by 1ppm (125Hz):");
si549::set_adpll(i2c::Dcxo::Main, main_adpll + 8591).expect("ADPLL write failed");
clock::spin_us(100_000);
print_tags();
si549::set_adpll(i2c::Dcxo::Main, main_adpll).expect("ADPLL write failed");
unsafe {
csr::wrpll::adpll_offset_helper_write(helper_adpll as u32);
csr::wrpll::adpll_offset_main_write(main_adpll as u32);
csr::wrpll::helper_dcxo_gpio_enable_write(0);
csr::wrpll::main_dcxo_gpio_enable_write(0);
csr::wrpll::helper_dcxo_errors_write(0xff);
csr::wrpll::main_dcxo_errors_write(0xff);
csr::wrpll::collector_reset_write(0);
}
clock::spin_us(1_000); // wait for the collector to produce meaningful output
unsafe {
csr::wrpll::filter_reset_write(0);
}
clock::spin_us(100_000);
print_tags();
// let mut tags = [0; 10];
// for i in 0..tags.len() {
// tags[i] = get_ddmtd_helper_tag();
// }
// info!("DDMTD helper tags: {:?}", tags);
unsafe {
csr::wrpll::filter_reset_write(1);
csr::wrpll::collector_reset_write(1);
}
clock::spin_us(50_000);
unsafe {
csr::wrpll::helper_dcxo_gpio_enable_write(1);
csr::wrpll::main_dcxo_gpio_enable_write(1);
}
unsafe {
info!("error {} {}",
csr::wrpll::helper_dcxo_errors_read(),
csr::wrpll::main_dcxo_errors_read());
}
info!("new ADPLL: {} {}",
si549::get_adpll(i2c::Dcxo::Helper)?,
si549::get_adpll(i2c::Dcxo::Main)?);
} else {
si549::set_adpll(i2c::Dcxo::Helper, 0).expect("ADPLL write failed");
si549::set_adpll(i2c::Dcxo::Main, 0).expect("ADPLL write failed");
}
Ok(())
}
pub fn select_recovered_clock(rc: bool) {
if rc {
info!("switching to recovered clock");
} else {
info!("switching to local XO clock");
}
match select_recovered_clock_int(rc) {
Ok(()) => info!("clock transition completed"),
Err(e) => error!("clock transition failed: {}", e)
}
}
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