PWM works

examples/embassy/src/bin/pwm.rs

@@ -0,0 +1,151 @@
+//! PWM example which uses a PWM pin routed through EMIO.
+//!
+//! On the Zedboard, the PWM waveform output will be on the W12 pin of PMOD JB1. The Zedboard
+//! reference FPGA design must be flashed onto the Zedboard for this to work.
+#![no_std]
+#![no_main]
+
+use core::panic::PanicInfo;
+use cortex_ar::asm::nop;
+use embassy_executor::Spawner;
+use embassy_time::{Duration, Ticker};
+use embedded_hal::{digital::StatefulOutputPin, pwm::SetDutyCycle};
+use embedded_io::Write;
+use fugit::RateExtU32;
+use log::{error, info};
+use zynq7000_hal::{
+    BootMode,
+    clocks::Clocks,
+    gic::{GicConfigurator, GicInterruptHelper, Interrupt},
+    gpio::{MioPins, PinState},
+    gtc::Gtc,
+    time::Hertz,
+    uart::{ClkConfigRaw, Uart, UartConfig},
+};
+
+use zynq7000::PsPeripherals;
+use zynq7000_rt as _;
+
+// Define the clock frequency as a constant
+const PS_CLOCK_FREQUENCY: Hertz = Hertz::from_raw(33_333_300);
+
+/// Entry point (not called like a normal main function)
+#[unsafe(no_mangle)]
+pub extern "C" fn boot_core(cpu_id: u32) -> ! {
+    if cpu_id != 0 {
+        panic!("unexpected CPU ID {}", cpu_id);
+    }
+    main();
+}
+
+#[embassy_executor::main]
+#[unsafe(export_name = "main")]
+async fn main(_spawner: Spawner) -> ! {
+    let dp = PsPeripherals::take().unwrap();
+    // Clock was already initialized by PS7 Init TCL script or FSBL, we just read it.
+    let clocks = Clocks::new_from_regs(PS_CLOCK_FREQUENCY).unwrap();
+    // Set up the global interrupt controller.
+    let mut gic = GicConfigurator::new_with_init(dp.gicc, dp.gicd);
+    gic.enable_all_interrupts();
+    gic.set_all_spi_interrupt_targets_cpu0();
+    gic.enable();
+    unsafe {
+        gic.enable_interrupts();
+    }
+    let mio_pins = MioPins::new(dp.gpio);
+
+    // Set up global timer counter and embassy time driver.
+    let gtc = Gtc::new(dp.gtc, clocks.arm_clocks());
+    zynq7000_embassy::init(clocks.arm_clocks(), gtc);
+
+    // Unwrap is okay, the address is definitely valid.
+    let ttc_0 = zynq7000_hal::ttc::Ttc::new(dp.ttc_0).unwrap();
+    let mut pwm =
+        zynq7000_hal::ttc::Pwm::new_with_cpu_clk(ttc_0.ch0, clocks.arm_clocks(), 1000.Hz())
+            .unwrap();
+    pwm.set_duty_cycle_percent(50).unwrap();
+
+    // Set up the UART, we are logging with it.
+    let uart_clk_config = ClkConfigRaw::new_autocalc_with_error(clocks.io_clocks(), 115200)
+        .unwrap()
+        .0;
+    let uart_tx = mio_pins.mio48.into_uart();
+    let uart_rx = mio_pins.mio49.into_uart();
+    let mut uart = Uart::new_with_mio(
+        dp.uart_1,
+        UartConfig::new_with_clk_config(uart_clk_config),
+        (uart_tx, uart_rx),
+    )
+    .unwrap();
+    uart.write_all(b"-- Zynq 7000 Embassy Hello World --\n\r")
+        .unwrap();
+    // Safety: We are not multi-threaded yet.
+    unsafe { zynq7000_hal::log::init_unsafe_single_core(uart, log::LevelFilter::Trace, false) };
+
+    let boot_mode = BootMode::new();
+    info!("Boot mode: {:?}", boot_mode);
+
+    let mut ticker = Ticker::every(Duration::from_millis(1000));
+    let mut led = mio_pins.mio7.into_output(PinState::Low);
+    let mut current_duty = 0;
+    loop {
+        led.toggle().unwrap();
+
+        pwm.set_duty_cycle_percent(current_duty).unwrap();
+        info!("Setting duty cycle to {}%", current_duty);
+        current_duty += 5;
+        if current_duty > 100 {
+            current_duty = 0;
+        }
+
+        ticker.next().await;
+    }
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _irq_handler() {
+    let mut gic_helper = GicInterruptHelper::new();
+    let irq_info = gic_helper.acknowledge_interrupt();
+    match irq_info.interrupt() {
+        Interrupt::Sgi(_) => (),
+        Interrupt::Ppi(ppi_interrupt) => {
+            if ppi_interrupt == zynq7000_hal::gic::PpiInterrupt::GlobalTimer {
+                unsafe {
+                    zynq7000_embassy::on_interrupt();
+                }
+            }
+        }
+        Interrupt::Spi(_spi_interrupt) => (),
+        Interrupt::Invalid(_) => (),
+        Interrupt::Spurious => (),
+    }
+    gic_helper.end_of_interrupt(irq_info);
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _abort_handler() {
+    loop {
+        nop();
+    }
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _undefined_handler() {
+    loop {
+        nop();
+    }
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _prefetch_handler() {
+    loop {
+        nop();
+    }
+}
+
+/// Panic handler
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    error!("Panic: {:?}", info);
+    loop {}
+}

zedboard-fpga-design/src/zedboard.xdc

@@ -70,6 +70,6 @@ set_property IOSTANDARD LVCMOS33 [get_ports UART_rxd]
 set_property PACKAGE_PIN AA11 [get_ports UART_txd]
 set_property IOSTANDARD LVCMOS33 [get_ports UART_txd]
 
-# TTC1 Wave Out
-set_property PACKAGE_PIN W12 [get_ports {TTC1_WAVEOUT}]
-set_property IOSTANDARD LVCMOS33 [get_ports {TTC1_WAVEOUT}]
+# TTC0 Wave Out
+set_property PACKAGE_PIN W12 [get_ports {TTC0_WAVEOUT}]
+set_property IOSTANDARD LVCMOS33 [get_ports {TTC0_WAVEOUT}]

zynq7000-hal/src/ttc.rs

@@ -1,8 +1,10 @@
 //! Triple-timer counter (TTC) high-level driver.
+//!
+//! This module also contains support for PWM and output waveform generation.
 
 use core::convert::Infallible;
 
-use arbitrary_int::{u3, u4};
+use arbitrary_int::{Number, u3, u4};
 use zynq7000::ttc::{MmioTtc, TTC_0_BASE_ADDR, TTC_1_BASE_ADDR};
 
 #[cfg(not(feature = "7z010-7z007s-clg225"))]
@@ -87,6 +89,8 @@ pub struct Ttc {
 impl Ttc {
     /// Create a new TTC instance. The passed TTC peripheral instance MUST point to a valid
     /// processing system TTC peripheral.
+    ///
+    /// Returns [None] if the passed peripheral block does not have a valid PS TTC address.
     pub fn new(ps_ttc: impl PsTtc) -> Option<Self> {
         ps_ttc.id()?;
         let regs = ps_ttc.reg_block();
@@ -116,6 +120,14 @@ impl TtcChannel {
         &mut self.regs
     }
 
+    #[inline]
+    pub fn read_counter(&self) -> u16 {
+        self.regs
+            .read_current_counter(self.id as usize)
+            .unwrap()
+            .count()
+    }
+
     pub fn id(&self) -> ChannelId {
         self.id
     }
@@ -137,16 +149,28 @@ pub enum TtcConstructionError {
     FrequencyIsZero(#[from] FrequencyIsZeroError),
 }
 
-pub fn calculate_prescaler_reg_and_interval_ticks(mut ref_clk: Hertz, freq: Hertz) -> (u4, u16) {
+pub fn calculate_prescaler_reg_and_interval_ticks(
+    mut ref_clk: Hertz,
+    freq: Hertz,
+) -> (Option<u4>, u16) {
     // TODO: Can this be optimized?
-    let mut prescaler_reg = 0;
+    let mut prescaler_reg: Option<u4> = None;
     let mut tick_val = ref_clk / freq;
     while tick_val > u16::MAX as u32 {
         ref_clk /= 2;
-        prescaler_reg += 1;
+        if let Some(prescaler_reg) = prescaler_reg {
+            // TODO: Better error handling for this case? Can this even happen?
+            if prescaler_reg.value() == u4::MAX.value() {
+                break;
+            } else {
+                prescaler_reg.checked_add(u4::new(1));
+            }
+        } else {
+            prescaler_reg = Some(u4::new(0));
+        }
         tick_val = ref_clk / freq;
     }
-    (u4::new(prescaler_reg), tick_val as u16)
+    (prescaler_reg, tick_val as u16)
 }
 
 pub struct Pwm {
@@ -155,8 +179,9 @@ pub struct Pwm {
 }
 
 impl Pwm {
-    /// Create a new PWM instance which uses the CPU 1x clock as the clock source.
-    pub fn new_with_mio_wave_out(
+    /// Create a new PWM instance which uses the CPU 1x clock as the clock source and also uses
+    /// a MIO output pin for the waveform output.
+    pub fn new_with_cpu_clk_and_mio_waveout(
         channel: TtcChannel,
         arm_clocks: &ArmClocks,
         freq: Hertz,
@@ -165,16 +190,30 @@ impl Pwm {
         if wave_out.mux_conf() != TTC_MUX_CONF {
             return Err(InvalidTtcPinConfigError(wave_out.mux_conf()).into());
         }
+        Ok(Self::new_with_cpu_clk(channel, arm_clocks, freq)?)
+    }
+
+    /// Create a new PWM instance which uses the CPU 1x clock as the clock source.
+    pub fn new_with_cpu_clk(
+        channel: TtcChannel,
+        arm_clocks: &ArmClocks,
+        freq: Hertz,
+    ) -> Result<Self, FrequencyIsZeroError> {
+        Self::new_generic(channel, arm_clocks.cpu_1x_clk(), freq)
+    }
+
+    /// Create a new PWM instance based on a reference clock source.
+    pub fn new_generic(
+        channel: TtcChannel,
+        ref_clk: Hertz,
+        freq: Hertz,
+    ) -> Result<Self, FrequencyIsZeroError> {
         if freq.raw() == 0 {
-            return Err(FrequencyIsZeroError.into());
+            return Err(FrequencyIsZeroError);
         }
-        let (prescaler_reg, tick_val) =
-            calculate_prescaler_reg_and_interval_ticks(arm_clocks.cpu_1x_clk(), freq);
+        let (prescaler_reg, tick_val) = calculate_prescaler_reg_and_interval_ticks(ref_clk, freq);
         let id = channel.id() as usize;
-        let mut pwm = Self {
-            channel,
-            ref_clk: arm_clocks.cpu_1x_clk(),
-        };
+        let mut pwm = Self { channel, ref_clk };
         pwm.set_up_and_configure_pwm(id, prescaler_reg, tick_val);
         Ok(pwm)
     }
@@ -193,6 +232,11 @@ impl Pwm {
         Ok(())
     }
 
+    #[inline]
+    pub fn ttc_channel_mut(&mut self) -> &mut TtcChannel {
+        &mut self.channel
+    }
+
     #[inline]
     pub fn max_duty_cycle(&self) -> u16 {
         self.channel
@@ -229,7 +273,7 @@ impl Pwm {
             .unwrap();
     }
 
-    fn set_up_and_configure_pwm(&mut self, id: usize, prescaler_reg: u4, tick_val: u16) {
+    fn set_up_and_configure_pwm(&mut self, id: usize, prescaler_reg: Option<u4>, tick_val: u16) {
         // Disable the counter first.
         self.channel
             .regs
@@ -244,8 +288,8 @@ impl Pwm {
                 zynq7000::ttc::ClockControl::builder()
                     .with_ext_clk_edge(false)
                     .with_clk_src(zynq7000::ttc::ClockSource::Pclk)
-                    .with_prescaler(prescaler_reg)
-                    .with_prescale_enable(prescaler_reg.value() > 0)
+                    .with_prescaler(prescaler_reg.unwrap_or(u4::new(0)))
+                    .with_prescale_enable(prescaler_reg.is_some())
                     .build(),
             )
             .unwrap();
@@ -266,10 +310,10 @@ impl Pwm {
             .write_cnt_ctrl(
                 id,
                 zynq7000::ttc::CounterControl::builder()
-                    .with_wave_polarity(zynq7000::ttc::WavePolarity::HighToLowOnMatch1)
+                    .with_wave_polarity(zynq7000::ttc::WavePolarity::LowToHighOnMatch1)
                     .with_wave_enable_n(zynq7000::ttc::WaveEnable::Enable)
                     .with_reset(true)
-                    .with_match_enable(false)
+                    .with_match_enable(true)
                     .with_decrementing(false)
                     .with_mode(zynq7000::ttc::Mode::Interval)
                     .with_disable(false)

zynq7000/src/ttc.rs

@@ -1,12 +1,14 @@
 //! Triple-timer counter (TTC) register module.
 use arbitrary_int::u4;
 
-pub const TTC_0_BASE_ADDR: usize = 0xF800_1004;
-pub const TTC_1_BASE_ADDR: usize = 0xF800_2004;
+pub const TTC_0_BASE_ADDR: usize = 0xF800_1000;
+pub const TTC_1_BASE_ADDR: usize = 0xF800_2000;
 
+#[derive(Debug, Default)]
 #[bitbybit::bitenum(u1, exhaustive = true)]
 pub enum ClockSource {
     /// PS internal bus clock.
+    #[default]
     Pclk = 0b0,
     External = 0b1,
 }
@@ -25,13 +27,14 @@ pub struct ClockControl {
     prescale_enable: bool,
 }
 
+#[derive(Debug)]
 #[bitbybit::bitenum(u1, exhaustive = true)]
 pub enum Mode {
     Overflow = 0b0,
     Interval = 0b1,
 }
 
-#[derive(Default)]
+#[derive(Debug, Default)]
 #[bitbybit::bitenum(u1, exhaustive = true)]
 pub enum WavePolarity {
     /// The waveform output goes from high to low on a match 0 interrupt and returns high on
@@ -43,6 +46,7 @@ pub enum WavePolarity {
     LowToHighOnMatch1 = 0b1,
 }
 
+#[derive(Debug)]
 #[bitbybit::bitenum(u1, exhaustive = true)]
 pub enum WaveEnable {
     Enable = 0b0,
@@ -158,6 +162,8 @@ pub struct Ttc {
     event_reg: [EventCount; 3],
 }
 
+static_assertions::const_assert_eq!(core::mem::size_of::<Ttc>(), 0x84);
+
 impl Ttc {
     /// Create a new TTC MMIO instance for TTC0 at address [TTC_0_BASE_ADDR].
     ///