From ecd53c916c5448c441b15a3d8e67c2ed38920607 Mon Sep 17 00:00:00 2001
From: Bob McWhirter <bmcwhirt@redhat.com>
Date: Tue, 8 Jun 2021 14:04:56 -0400
Subject: [PATCH] Small changes to support DAC example.

---
 examples/stm32l4/Cargo.toml     |  4 ++
 examples/stm32l4/src/bin/dac.rs | 92 +++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+)
 create mode 100644 examples/stm32l4/src/bin/dac.rs

diff --git a/examples/stm32l4/Cargo.toml b/examples/stm32l4/Cargo.toml
index ca53f08b..48125c4f 100644
--- a/examples/stm32l4/Cargo.toml
+++ b/examples/stm32l4/Cargo.toml
@@ -22,6 +22,7 @@ embassy-traits = { version = "0.1.0", path = "../../embassy-traits", features =
 embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["defmt", "defmt-trace", "stm32l4s5vi"]  }
 embassy-extras = {version = "0.1.0", path = "../../embassy-extras" }
 stm32l4 = { version = "0.13", features = ["stm32l4x5" ] }
+stm32l4xx-hal = { version = "0.6.0", features = ["stm32l4x5"] }
 
 defmt = "0.2.0"
 defmt-rtt = "0.2.0"
@@ -33,3 +34,6 @@ panic-probe = { version = "0.2.0", features= ["print-defmt"] }
 futures = { version = "0.3.8", default-features = false, features = ["async-await"] }
 rtt-target = { version = "0.3", features = ["cortex-m"] }
 heapless = { version = "0.7.1", default-features = false }
+
+micromath = "2.0.0"
+
diff --git a/examples/stm32l4/src/bin/dac.rs b/examples/stm32l4/src/bin/dac.rs
new file mode 100644
index 00000000..5bd5dafb
--- /dev/null
+++ b/examples/stm32l4/src/bin/dac.rs
@@ -0,0 +1,92 @@
+#![no_std]
+#![no_main]
+#![feature(trait_alias)]
+#![feature(min_type_alias_impl_trait)]
+#![feature(impl_trait_in_bindings)]
+#![feature(type_alias_impl_trait)]
+
+#[path = "../example_common.rs"]
+mod example_common;
+
+use embassy_stm32::gpio::{Level, Output, Input, Pull, NoPin};
+use embedded_hal::digital::v2::{OutputPin, InputPin};
+use example_common::*;
+
+use cortex_m_rt::entry;
+//use stm32f4::stm32f429 as pac;
+use stm32l4::stm32l4x5 as pac;
+use embassy_stm32::spi::{Spi, MODE_0, ByteOrder, Config};
+use embassy_stm32::time::Hertz;
+use embedded_hal::blocking::spi::Transfer;
+use stm32l4xx_hal::{rcc, prelude::*};
+use stm32l4xx_hal::rcc::PllSource;
+use embassy_stm32::dac::{Dac, Value, Channel};
+use stm32l4xx_hal::gpio::PA4;
+
+#[entry]
+fn main() -> ! {
+    info!("Hello World, dude!");
+    //let pp = pac::Peripherals::take().unwrap();
+    let pp = stm32l4xx_hal::stm32::Peripherals::take().unwrap();
+    let mut flash = pp.FLASH.constrain();
+    let mut rcc = pp.RCC.constrain();
+    let mut pwr = pp.PWR.constrain(&mut rcc.apb1r1);
+
+    // TRY the other clock configuration
+    // let clocks = rcc.cfgr.freeze(&mut flash.acr);
+    let clocks = rcc
+        .cfgr
+        .sysclk(80.mhz())
+        .pclk1(80.mhz())
+        .pclk2(80.mhz())
+        .pll_source(PllSource::HSI16)
+        .freeze(&mut flash.acr, &mut pwr);
+
+    let pp = unsafe { pac::Peripherals::steal() };
+
+    pp.DBGMCU.cr.modify(|_, w| {
+        w.dbg_sleep().set_bit();
+        w.dbg_standby().set_bit();
+        w.dbg_stop().set_bit()
+    });
+
+    pp.RCC.apb1enr1.modify(|_, w| {
+        w.dac1en().set_bit();
+        w
+    });
+
+    pp.RCC.ahb2enr.modify(|_, w| {
+        w.gpioaen().set_bit();
+        w.gpioben().set_bit();
+        w.gpiocen().set_bit();
+        w.gpioden().set_bit();
+        w.gpioeen().set_bit();
+        w.gpiofen().set_bit();
+        w
+    });
+
+    let p = embassy_stm32::init(Default::default());
+
+    let mut dac = Dac::new(p.DAC1, p.PA4, NoPin);
+
+    loop {
+        for v in 0..=255 {
+            dac.set(Channel::Ch1, Value::Bit8(to_sine_wave(v)));
+            dac.trigger( Channel::Ch1 );
+        }
+    }
+}
+
+use micromath::F32Ext;
+
+fn to_sine_wave(v: u8) -> u8 {
+    if v >= 128 {
+        // top half
+        let r = 3.14 * ( (v-128) as f32/ 128.0) ;
+        (r.sin() * 128.0 + 127.0) as u8
+    } else {
+        // bottom half
+        let r = 3.14 + 3.14 * (v as f32/ 128.0);
+        (r.sin() * 128.0 + 127.0) as u8
+    }
+}