Scale clock dividers in HD44780, rotary encoder, and stepper driver based on system clock frequency

3 files changed, 23 insertions, 5 deletions

diff --git a/embassy-rp/src/pio_programs/hd44780.rs b/embassy-rp/src/pio_programs/hd44780.rs
index 5846a8027..3aa54495f 100644
--- a/embassy-rp/src/pio_programs/hd44780.rs
+++ b/embassy-rp/src/pio_programs/hd44780.rs
@@ -1,5 +1,6 @@
 //! [HD44780 display driver](https://www.sparkfun.com/datasheets/LCD/HD44780.pdf)
 
+use crate::clocks::clk_sys_freq;
 use crate::dma::{AnyChannel, Channel};
 use crate::pio::{
     Common, Config, Direction, FifoJoin, Instance, Irq, LoadedProgram, PioPin, ShiftConfig, ShiftDirection,
@@ -134,7 +135,12 @@ impl<'l, P: Instance, const S: usize> PioHD44780<'l, P, S> {
 
         let mut cfg = Config::default();
         cfg.use_program(&word_prg.prg, &[&e]);
-        cfg.clock_divider = 125u8.into();
+
+        // Scale the divider based on system clock frequency
+        // Original: 125 at 125 MHz (1 MHz PIO clock)
+        let word_divider = (clk_sys_freq() / 1_000_000) as u8; // Target 1 MHz PIO clock
+        cfg.clock_divider = word_divider.into();
+
         cfg.set_out_pins(&[&db4, &db5, &db6, &db7]);
         cfg.shift_out = ShiftConfig {
             auto_fill: true,
@@ -160,7 +166,12 @@ impl<'l, P: Instance, const S: usize> PioHD44780<'l, P, S> {
 
         let mut cfg = Config::default();
         cfg.use_program(&seq_prg.prg, &[&e]);
-        cfg.clock_divider = 8u8.into(); // ~64ns/insn
+
+        // Original: 8 at 125 MHz (~15.6 MHz PIO clock)
+        // Comment says ~64ns/insn which is 1/(15.6 MHz) = ~64ns
+        let seq_divider = (clk_sys_freq() / 15_600_000) as u8; // Target ~15.6 MHz PIO clock (~64ns/insn)
+        cfg.clock_divider = seq_divider.into();
+
         cfg.set_jmp_pin(&db7);
         cfg.set_set_pins(&[&rs, &rw]);
         cfg.set_out_pins(&[&db4, &db5, &db6, &db7]);
diff --git a/embassy-rp/src/pio_programs/rotary_encoder.rs b/embassy-rp/src/pio_programs/rotary_encoder.rs
index e520da8a3..7bd463bb8 100644
--- a/embassy-rp/src/pio_programs/rotary_encoder.rs
+++ b/embassy-rp/src/pio_programs/rotary_encoder.rs
@@ -2,6 +2,7 @@
 
 use fixed::traits::ToFixed;
 
+use crate::clocks::clk_sys_freq;
 use crate::gpio::Pull;
 use crate::pio::{
     Common, Config, Direction as PioDirection, FifoJoin, Instance, LoadedProgram, PioPin, ShiftDirection, StateMachine,
@@ -48,7 +49,12 @@ impl<'d, T: Instance, const SM: usize> PioEncoder<'d, T, SM> {
         cfg.set_in_pins(&[&pin_a, &pin_b]);
         cfg.fifo_join = FifoJoin::RxOnly;
         cfg.shift_in.direction = ShiftDirection::Left;
-        cfg.clock_divider = 10_000.to_fixed();
+        
+        // Original: 10_000 at 125 MHz (12.5 KHz PIO clock)
+        // Scale divider to maintain same PIO clock frequency at different system clocks
+        let divider = (clk_sys_freq() as f32 / 12_500.0).to_fixed();
+        cfg.clock_divider = divider;
+        
         cfg.use_program(&program.prg, &[]);
         sm.set_config(&cfg);
         sm.set_enable(true);
diff --git a/embassy-rp/src/pio_programs/stepper.rs b/embassy-rp/src/pio_programs/stepper.rs
index 495191659..6878c32f5 100644
--- a/embassy-rp/src/pio_programs/stepper.rs
+++ b/embassy-rp/src/pio_programs/stepper.rs
@@ -6,6 +6,7 @@ use fixed::traits::ToFixed;
 use fixed::types::extra::U8;
 use fixed::FixedU32;
 
+use crate::clocks::clk_sys_freq;
 use crate::pio::{Common, Config, Direction, Instance, Irq, LoadedProgram, PioPin, StateMachine};
 use crate::Peri;
 
@@ -64,7 +65,7 @@ impl<'d, T: Instance, const SM: usize> PioStepper<'d, T, SM> {
         sm.set_pin_dirs(Direction::Out, &[&pin0, &pin1, &pin2, &pin3]);
         let mut cfg = Config::default();
         cfg.set_out_pins(&[&pin0, &pin1, &pin2, &pin3]);
-        cfg.clock_divider = (125_000_000 / (100 * 136)).to_fixed();
+        cfg.clock_divider = (clk_sys_freq() / (100 * 136)).to_fixed();
         cfg.use_program(&program.prg, &[]);
         sm.set_config(&cfg);
         sm.set_enable(true);
@@ -73,7 +74,7 @@ impl<'d, T: Instance, const SM: usize> PioStepper<'d, T, SM> {
 
     /// Set pulse frequency
     pub fn set_frequency(&mut self, freq: u32) {
-        let clock_divider: FixedU32<U8> = (125_000_000 / (freq * 136)).to_fixed();
+        let clock_divider: FixedU32<U8> = (clk_sys_freq() / (freq * 136)).to_fixed();
         assert!(clock_divider <= 65536, "clkdiv must be <= 65536");
         assert!(clock_divider >= 1, "clkdiv must be >= 1");
         self.sm.set_clock_divider(clock_divider);