From 5d1cff57f9f5acd740a8b5f8c941beefdcc00176 Mon Sep 17 00:00:00 2001
From: "Matthias P. Braendli" <matthias.braendli@mpb.li>
Date: Sun, 28 Jun 2020 16:42:21 +0200
Subject: sw: configure si5351

---
 sw/demo1/src/main.rs | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 84 insertions(+), 3 deletions(-)

(limited to 'sw/demo1/src/main.rs')

diff --git a/sw/demo1/src/main.rs b/sw/demo1/src/main.rs
index 4f8ce6e..0b9f965 100644
--- a/sw/demo1/src/main.rs
+++ b/sw/demo1/src/main.rs
@@ -1,6 +1,8 @@
 #![no_main]
 #![no_std]
 
+use core::convert::TryInto;
+
 use cortex_m_rt::ExceptionFrame;
 use cortex_m_semihosting::hio;
 use panic_semihosting as _;
@@ -18,6 +20,45 @@ use si5351::{Si5351, Si5351Device};
 
 use core::fmt::Write;
 
+fn gcd(x: u32, y: u32) -> u32 {
+    let mut x = x;
+    let mut y = y;
+    while y != 0 {
+        let t = y;
+        y = x % y;
+        x = t;
+    }
+    x
+}
+
+fn clock_settings_for_pll(freq: u32, pll: u32) -> (u16, u32, u32) {
+    let a = pll / freq;
+    let b = pll - (a * freq);
+    let gcd = gcd(b, freq);
+
+    let b = b / gcd;
+    let c = freq / gcd;
+    (a.try_into().unwrap(), b, c)
+}
+
+fn clock_settings_with_pll_calculation(freq: u32, ref_clock: u32) -> (u16, u8, u32, u32) {
+    let mut divider : u32 = 900_000_000 / freq; // Calculate the division ratio. 900,000,000 is the maximum internal
+
+    if (divider % 2) == 1 {
+        divider -= 1 // Ensure an even integer division ratio
+    }
+
+    let pll_freq = divider * freq;
+    // mult is an integer that must be in the range 15..90
+    let mult = pll_freq / ref_clock;
+    let l = pll_freq % ref_clock;
+
+    let denom = 1048575;
+    let num = f64::from(l) * f64::from(denom) / f64::from(ref_clock);
+
+    (divider.try_into().unwrap(), mult.try_into().unwrap(), num as u32, denom)
+}
+
 fn print(step: usize) -> Result<(), core::fmt::Error> {
     let mut stdout = match hio::hstdout() {
         Ok(fd) => fd,
@@ -112,9 +153,49 @@ fn main() -> ! {
     let ref_clock = 25_000_000;
     let mut siclock = Si5351Device::new(i2c_busmanager.acquire(), false, ref_clock);
     siclock.init(si5351::CrystalLoad::_10).unwrap();
-    siclock.set_frequency(si5351::PLL::B, si5351::ClockOutput::Clk0, 28_000_000 + 4_915_200).unwrap();
-    siclock.set_frequency(si5351::PLL::A, si5351::ClockOutput::Clk1, 144_000_000 + 28_000_000).unwrap();
-    siclock.set_frequency(si5351::PLL::A, si5351::ClockOutput::Clk2, 4_915_100).unwrap();
+
+    // See freqplan.py for Si5351 frequency plan
+    // CLK1 = 116MHz
+    let pll_a_mult = 32;
+    siclock.setup_pll_int(si5351::PLL::A, 32).unwrap();
+
+    {
+        let clk1 = 116_000_000;
+        let (a, b, c) = clock_settings_for_pll(clk1, pll_a_mult * ref_clock);
+        siclock.setup_multisynth(si5351::Multisynth::MS1, a, b, c, si5351::OutputDivider::Div1).unwrap();
+        siclock.select_clock_pll(si5351::ClockOutput::Clk1, si5351::PLL::A);
+        siclock.set_clock_enabled(si5351::ClockOutput::Clk1, true);
+        siclock.flush_clock_control(si5351::ClockOutput::Clk1).unwrap();
+    }
+
+    {
+        let clk2 = 4_195_210;
+        let (a, b, c) = clock_settings_for_pll(clk2, pll_a_mult * ref_clock);
+        siclock.setup_multisynth(si5351::Multisynth::MS2, a, b, c, si5351::OutputDivider::Div1).unwrap();
+        siclock.select_clock_pll(si5351::ClockOutput::Clk2, si5351::PLL::A);
+        siclock.set_clock_enabled(si5351::ClockOutput::Clk2, true);
+        siclock.flush_clock_control(si5351::ClockOutput::Clk2).unwrap();
+    }
+
+    siclock.reset_pll(si5351::PLL::A).unwrap();
+
+    {
+        let clk0 = 23_000_000;
+
+        let (div, mult, num, denom) = clock_settings_with_pll_calculation(clk0, ref_clock);
+
+        siclock.setup_pll(si5351::PLL::B, mult, num, denom).unwrap();
+        siclock.setup_multisynth_int(si5351::Multisynth::MS0, div, si5351::OutputDivider::Div1).unwrap();
+
+        siclock.select_clock_pll(si5351::ClockOutput::Clk0, si5351::PLL::B);
+        siclock.set_clock_enabled(si5351::ClockOutput::Clk0, true);
+        siclock.flush_clock_control(si5351::ClockOutput::Clk0).unwrap();
+    }
+
+    siclock.reset_pll(si5351::PLL::B).unwrap();
+
+    siclock.flush_output_enabled().unwrap();
+
 
     lcd.set_cursor_pos(0, &mut delay).unwrap();
     lcd.write_str("Clocks set.     ", &mut delay).unwrap();
-- 
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