Implement I2C master writing and add example using SSD1306 display

Author: fmckeogh

Cargo.toml

@@ -43,6 +43,8 @@ void = { version = "1.0.2", default-features = false }
 
 [dev-dependencies]
 panic-halt = "0.2.0"
+ssd1306 = "0.3.1"
+embedded-graphics = "0.6.2"
 
 [[example]]
 name = "alloc"

examples/i2c.rs

@@ -0,0 +1,116 @@
+#![no_std]
+#![no_main]
+
+extern crate esp32_hal as hal;
+extern crate xtensa_lx6_rt;
+
+use {
+    core::panic::PanicInfo,
+    embedded_graphics::{
+        pixelcolor::BinaryColor, prelude::*, primitives::Circle, primitives::Rectangle,
+        style::PrimitiveStyle, style::PrimitiveStyleBuilder,
+    },
+    hal::{
+        clock_control::{self, sleep, CPUSource, ClockControl, ClockControlConfig},
+        dport::Split,
+        dprintln, i2c,
+        prelude::*,
+        timer::Timer,
+    },
+    ssd1306::{prelude::*, Builder},
+};
+
+#[no_mangle]
+fn main() -> ! {
+    let dp = esp32::Peripherals::take().unwrap();
+
+    let (mut dport, dport_clock_control) = dp.DPORT.split();
+
+    // setup clocks & watchdog
+    let mut clkcntrl = ClockControl::new(
+        dp.RTCCNTL,
+        dp.APB_CTRL,
+        dport_clock_control,
+        clock_control::XTAL_FREQUENCY_AUTO,
+    )
+    .unwrap();
+
+    // set desired clock frequencies
+    clkcntrl
+        .set_cpu_frequencies(
+            CPUSource::PLL,
+            80.MHz(),
+            CPUSource::PLL,
+            240.MHz(),
+            CPUSource::PLL,
+            80.MHz(),
+        )
+        .unwrap();
+
+    let (clkcntrl_config, mut watchdog) = clkcntrl.freeze().unwrap();
+    watchdog.disable();
+    let (_, _, _, mut watchdog0) = Timer::new(dp.TIMG0, clkcntrl_config);
+    watchdog0.disable();
+    let (_, _, _, mut watchdog1) = Timer::new(dp.TIMG1, clkcntrl_config);
+    watchdog1.disable();
+
+    let pins = dp.GPIO.split();
+
+    let i2c0 = i2c::I2C::new(
+        dp.I2C0,
+        i2c::Pins {
+            sda: pins.gpio4,
+            scl: pins.gpio15,
+        },
+        400_000,
+        &mut dport,
+    );
+
+    let mut display: GraphicsMode<_> = Builder::new().connect_i2c(i2c0).into();
+
+    let mut rst = pins.gpio16.into_push_pull_output();
+    rst.set_low().unwrap();
+    sleep(10.ms());
+    rst.set_high().unwrap();
+
+    display.init().unwrap();
+
+    loop {
+        display.clear();
+        Rectangle::new(Point::new(16, 24), Point::new(48, 40))
+            .into_styled(
+                PrimitiveStyleBuilder::new()
+                    .fill_color(BinaryColor::On)
+                    .build(),
+            )
+            .draw(&mut display)
+            .unwrap();
+        display.flush().unwrap();
+        sleep(500.ms());
+
+        display.clear();
+        Circle::new(Point::new(96, 32), 20)
+            .into_styled(PrimitiveStyle::with_fill(BinaryColor::On))
+            .draw(&mut display)
+            .unwrap();
+        display.flush().unwrap();
+        sleep(500.ms());
+    }
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    // park the other core
+    unsafe { ClockControlConfig {}.park_core(esp32_hal::get_other_core()) };
+
+    // print panic message
+    dprintln!("\n\n*** {:?}", info);
+
+    // park this core
+    unsafe { ClockControlConfig {}.park_core(esp32_hal::get_core()) };
+
+    dprintln!("Not reached because core is parked.");
+
+    // this statement will not be reached, but is needed to make this a diverging function
+    loop {}
+}