added DDS example

examples/stm32l0/Cargo.toml

@@ -6,7 +6,7 @@ license = "MIT OR Apache-2.0"
 
 [dependencies]
 # Change stm32l072cz to your chip name, if necessary.
-embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["defmt", "stm32l072cz", "time-driver-any", "exti", "memory-x"]  }
+embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["defmt", "stm32l072cz", "unstable-pac", "time-driver-any", "exti", "memory-x"]  }
 embassy-sync = { version = "0.6.0", path = "../../embassy-sync", features = ["defmt"] }
 embassy-executor = { version = "0.5.0", path = "../../embassy-executor", features = ["arch-cortex-m", "executor-thread", "defmt", "integrated-timers"] }
 embassy-time = { version = "0.3.1", path = "../../embassy-time", features = ["defmt", "defmt-timestamp-uptime", "tick-hz-32_768"] }

examples/stm32l0/src/bin/dds.rs

@@ -0,0 +1,117 @@
+#![no_std]
+#![no_main]
+
+use core::option::Option::Some;
+use defmt::info;
+use defmt_rtt as _; // global logger
+use embassy_executor::Spawner;
+use embassy_stm32::gpio::OutputType;
+use embassy_stm32::interrupt;
+use embassy_stm32::pac;
+use embassy_stm32::rcc::*;
+use embassy_stm32::time::hz;
+use embassy_stm32::timer::low_level::Timer as LLTimer;
+use embassy_stm32::timer::low_level::*;
+use embassy_stm32::timer::simple_pwm::PwmPin;
+use embassy_stm32::timer::Channel;
+use embassy_stm32::Config;
+use panic_probe as _;
+
+const DDS_SINE_DATA: [u8; 256] = [
+    0x80, 0x83, 0x86, 0x89, 0x8c, 0x8f, 0x92, 0x95, 0x98, 0x9c, 0x9f, 0xa2, 0xa5, 0xa8, 0xab, 0xae, 0xb0, 0xb3, 0xb6,
+    0xb9, 0xbc, 0xbf, 0xc1, 0xc4, 0xc7, 0xc9, 0xcc, 0xce, 0xd1, 0xd3, 0xd5, 0xd8, 0xda, 0xdc, 0xde, 0xe0, 0xe2, 0xe4,
+    0xe6, 0xe8, 0xea, 0xec, 0xed, 0xef, 0xf0, 0xf2, 0xf3, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfc, 0xfd,
+    0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfd, 0xfc, 0xfc, 0xfb,
+    0xfa, 0xf9, 0xf8, 0xf7, 0xf6, 0xf5, 0xf3, 0xf2, 0xf0, 0xef, 0xed, 0xec, 0xea, 0xe8, 0xe6, 0xe4, 0xe2, 0xe0, 0xde,
+    0xdc, 0xda, 0xd8, 0xd5, 0xd3, 0xd1, 0xce, 0xcc, 0xc9, 0xc7, 0xc4, 0xc1, 0xbf, 0xbc, 0xb9, 0xb6, 0xb3, 0xb0, 0xae,
+    0xab, 0xa8, 0xa5, 0xa2, 0x9f, 0x9c, 0x98, 0x95, 0x92, 0x8f, 0x8c, 0x89, 0x86, 0x83, 0x80, 0x7c, 0x79, 0x76, 0x73,
+    0x70, 0x6d, 0x6a, 0x67, 0x63, 0x60, 0x5d, 0x5a, 0x57, 0x54, 0x51, 0x4f, 0x4c, 0x49, 0x46, 0x43, 0x40, 0x3e, 0x3b,
+    0x38, 0x36, 0x33, 0x31, 0x2e, 0x2c, 0x2a, 0x27, 0x25, 0x23, 0x21, 0x1f, 0x1d, 0x1b, 0x19, 0x17, 0x15, 0x13, 0x12,
+    0x10, 0x0f, 0x0d, 0x0c, 0x0a, 0x09, 0x08, 0x07, 0x06, 0x05, 0x04, 0x03, 0x03, 0x02, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x02, 0x03, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
+    0x0a, 0x0c, 0x0d, 0x0f, 0x10, 0x12, 0x13, 0x15, 0x17, 0x19, 0x1b, 0x1d, 0x1f, 0x21, 0x23, 0x25, 0x27, 0x2a, 0x2c,
+    0x2e, 0x31, 0x33, 0x36, 0x38, 0x3b, 0x3e, 0x40, 0x43, 0x46, 0x49, 0x4c, 0x4f, 0x51, 0x54, 0x57, 0x5a, 0x5d, 0x60,
+    0x63, 0x67, 0x6a, 0x6d, 0x70, 0x73, 0x76, 0x79, 0x7c,
+];
+
+// frequency: 15625/(256/(DDS_INCR/2**24)) = 999,99999Hz
+static mut DDS_INCR: u32 = 0x10624DD2;
+
+// fractional phase accumulator
+static mut DDS_AKKU: u32 = 0x00000000;
+
+#[interrupt]
+fn TIM2() {
+    unsafe {
+        // get next value of DDS
+        DDS_AKKU = DDS_AKKU.wrapping_add(DDS_INCR);
+        let value = (DDS_SINE_DATA[(DDS_AKKU >> 24) as usize] as u16) << 3;
+
+        // set new output compare value
+        pac::TIM2.ccr(2).modify(|w| w.set_ccr(value));
+
+        // reset interrupt flag
+        pac::TIM2.sr().modify(|r| r.set_uif(false));
+    }
+}
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    info!("Hello World!");
+
+    // configure for 32MHz (HSI16 * 6 / 3)
+    let mut config = Config::default();
+    config.rcc.sys = Sysclk::PLL1_R;
+    config.rcc.hsi = true;
+    config.rcc.pll = Some(Pll {
+        source: PllSource::HSI,
+        div: PllDiv::DIV3,
+        mul: PllMul::MUL6,
+    });
+
+    let p = embassy_stm32::init(config);
+
+    // setup PWM pin in AF mode
+    let _ch3 = PwmPin::new_ch3(p.PA2, OutputType::PushPull);
+
+    // initialize timer
+    let timer = LLTimer::new(p.TIM2);
+
+    // set counting mode
+    timer.set_counting_mode(CountingMode::EdgeAlignedUp);
+
+    // set pwm sample frequency
+    timer.set_frequency(hz(15625));
+
+    // enable outputs
+    timer.enable_outputs();
+
+    // start timer
+    timer.start();
+
+    // set output compare mode
+    timer.set_output_compare_mode(Channel::Ch3, OutputCompareMode::PwmMode1);
+
+    // set output compare preload
+    timer.set_output_compare_preload(Channel::Ch3, true);
+
+    // set output polarity
+    timer.set_output_polarity(Channel::Ch3, OutputPolarity::ActiveHigh);
+
+    // set compare value
+    timer.set_compare_value(Channel::Ch3, timer.get_max_compare_value() / 2);
+
+    // enable pwm channel
+    timer.enable_channel(Channel::Ch3, true);
+
+    // enable timer interrupts
+    timer.enable_update_interrupt(true);
+    unsafe { cortex_m::peripheral::NVIC::unmask(interrupt::TIM2) };
+
+    async {
+        loop {
+            embassy_time::Timer::after_millis(5000).await;
+        }
+    }
+    .await;
+}