From 5b12c42aa9f54838836d7d560f2fdc8a624105f5 Mon Sep 17 00:00:00 2001
From: Nikita Sivakov <sivakov512@icloud.com>
Date: Sun, 5 Nov 2023 01:49:05 +0100
Subject: [PATCH] Example of fetching GPS data with NMEA via UART

---
 Cargo.toml           |   1 +
 examples/gps_nmea.rs | 122 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 123 insertions(+)
 create mode 100644 examples/gps_nmea.rs

diff --git a/Cargo.toml b/Cargo.toml
index 6b6f009..51b923e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,6 +11,7 @@ defmt = "0.3"
 defmt-rtt = "0.4"
 embedded-hal = { version = "0.2", features = ["unproven"] }
 fugit = "0.3"
+nmea = { version = "0.6", default_features = false, features = ["all-sentences"] }
 panic-probe = { version = "0.3", features = ["print-defmt"] }
 # Board support for RP Pico
 rp-pico = "0.8"
diff --git a/examples/gps_nmea.rs b/examples/gps_nmea.rs
new file mode 100644
index 0000000..ef758dc
--- /dev/null
+++ b/examples/gps_nmea.rs
@@ -0,0 +1,122 @@
+#![no_main]
+#![no_std]
+
+use rp_pico as bsp;
+
+use bsp::entry;
+use defmt_rtt as _;
+use fugit::RateExtU32;
+use panic_probe as _;
+
+use bsp::hal::{
+    self,
+    clocks::{init_clocks_and_plls, Clock},
+    gpio::bank0::{Gpio0, Gpio1, Gpio4, Gpio5},
+    pac,
+    sio::Sio,
+    uart::{DataBits, StopBits, UartConfig, UartPeripheral},
+    watchdog::Watchdog,
+};
+use core::fmt::Write;
+use defmt::info;
+use embedded_hal::serial::Read;
+
+type GPSUartPins = (
+    hal::gpio::Pin<Gpio4, hal::gpio::FunctionUart, hal::gpio::PullNone>,
+    hal::gpio::Pin<Gpio5, hal::gpio::FunctionUart, hal::gpio::PullNone>,
+);
+
+type DebugUartPins = (
+    hal::gpio::Pin<Gpio0, hal::gpio::FunctionUart, hal::gpio::PullNone>,
+    hal::gpio::Pin<Gpio1, hal::gpio::FunctionUart, hal::gpio::PullNone>,
+);
+
+const NMEA_LENGTH: usize = 164;
+const START_BYTE: u8 = 36;
+
+#[entry]
+fn main() -> ! {
+    info!("Running gps_nmea program");
+
+    let mut pac = pac::Peripherals::take().unwrap();
+    let mut watchdog = Watchdog::new(pac.WATCHDOG);
+    let sio = Sio::new(pac.SIO);
+
+    let clocks = init_clocks_and_plls(
+        bsp::XOSC_CRYSTAL_FREQ,
+        pac.XOSC,
+        pac.CLOCKS,
+        pac.PLL_SYS,
+        pac.PLL_USB,
+        &mut pac.RESETS,
+        &mut watchdog,
+    )
+    .ok()
+    .unwrap();
+
+    let pins = bsp::Pins::new(
+        pac.IO_BANK0,
+        pac.PADS_BANK0,
+        sio.gpio_bank0,
+        &mut pac.RESETS,
+    );
+
+    let mut gps_uart = UartPeripheral::new(
+        pac.UART1,
+        (pins.gpio4.reconfigure(), pins.gpio5.reconfigure()) as GPSUartPins,
+        &mut pac.RESETS,
+    )
+    .enable(
+        UartConfig::new(9_600.Hz(), DataBits::Eight, None, StopBits::One),
+        clocks.peripheral_clock.freq(),
+    )
+    .unwrap();
+
+    let mut debug_uart = UartPeripheral::new(
+        pac.UART0,
+        (pins.gpio0.reconfigure(), pins.gpio1.reconfigure()) as DebugUartPins,
+        &mut pac.RESETS,
+    )
+    .enable(
+        UartConfig::new(9_600.Hz(), DataBits::Eight, None, StopBits::One),
+        clocks.peripheral_clock.freq(),
+    )
+    .unwrap();
+
+    let mut buffer: [u8; NMEA_LENGTH] = [0; NMEA_LENGTH];
+    let mut pointer = 0;
+
+    let mut parser = nmea::Nmea::default();
+
+    loop {
+        while let Ok(byte) = gps_uart.read() {
+            if pointer == 0 && byte != START_BYTE {
+                continue;
+            }
+
+            if pointer >= NMEA_LENGTH {
+                pointer = 0;
+                continue;
+            }
+
+            if byte == START_BYTE {
+                if pointer != 0 {
+                    if let Ok(ascii) = core::str::from_utf8(&buffer[..pointer]) {
+                        write!(debug_uart, "{}", ascii).unwrap();
+
+                        if let Ok(_) = parser.parse(ascii) {
+                            write!(debug_uart, "{:?}", parser).unwrap();
+                        }
+
+                        write!(debug_uart, "\n").unwrap();
+                    }
+                }
+
+                pointer = 0
+            }
+
+            buffer[pointer] = byte;
+            pointer += 1;
+        }
+    }
+}