examples: Clarify SPI clock selection

.github/workflows/ci.yml

@@ -1,117 +0,0 @@
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-
-on:
-  push:
-    branches: [master]
-
-  pull_request:
-    branches: [master]
-
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-  CARGO_TERM_COLOR: always
-
-jobs:
-  style:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
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-      - uses: actions/checkout@v2
-
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          target: thumbv7em-none-eabihf
-          override: true
-          components: clippy
-
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-        uses: actions-rs/cargo@v1
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-  compile:
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-      matrix:
-        toolchain:
-          - stable
-          - beta
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-      - uses: actions/checkout@v2
-
-      - name: Install Rust ${{ matrix.toolchain }}
-        uses: actions-rs/toolchain@v1
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-          toolchain: ${{ matrix.toolchain }}
-          target: thumbv7em-none-eabihf
-          override: true
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-      - name: Cargo Check
-        uses: actions-rs/cargo@v1
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-        uses: actions-rs/cargo@v1
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-          args: --release --all-features
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-      - name: Cargo Build [Examples]
-        uses: actions-rs/cargo@v1
-        with:
-          command: build
-          args: --examples --all-features

Cargo.toml

@@ -3,7 +3,7 @@ categories = ["embedded", "no-std"]
 name = "enc424j600"
 description = "Embbeded Rust Ethernet driver for ENC424J600 Ethernet controller with SPI interface"
 authors = ["Harry Ho <hh@m-labs.hk>", "Dip Cheung <dc@m-labs.hk>"]
-version = "0.3.0"
+version = "0.2.0"
 keywords = ["ethernet", "eth", "enc424j600", "stm32", "stm32f4xx"]
 repository = "https://git.m-labs.hk/M-Labs/ENC424J600"
 edition = "2018"
@@ -13,30 +13,46 @@ license = "BSD-2-Clause"
 volatile-register = "0.2"
 aligned = "0.3"
 embedded-hal = "0.2"
-smoltcp = { version = "0.7.0", default-features = false, features = [ "socket-raw", "proto-ipv4",
-    "proto-ipv6", "socket-tcp", "ethernet"], optional = true }
-cortex-m = {version = "0.5", optional = true }
-
+smoltcp = { version = "0.7.0", default-features = false, features = [ "socket-raw", "proto-ipv4", "proto-ipv6" ], optional = true }
+# Dependencies for NAL
+embedded-time = { version = "0.10.1", optional = true }
+embedded-nal = { version = "0.1.0", optional = true }
+heapless = { version = "0.5.6", optional = true }
 # Optional dependencies for building examples
-[dev-dependencies]
-stm32f4xx-hal = { version = "0.8", features = ["stm32f407", "rt"] }
-cortex-m-rt = "0.6"
-cortex-m-rtic = "0.5.3"
-panic-itm = "0.4"
-log = "0.4"
+stm32f4xx-hal = { version = "0.8", optional = true }
+cortex-m = { version = "0.5", optional = true }
+cortex-m-rt = { version = "0.6", optional = true }
+cortex-m-rtic = { version = "0.5.3", optional = true }
+panic-itm = { version = "0.4", optional = true }
+log = { version = "0.4", optional = true }
 
 [features]
 smoltcp-phy = ["smoltcp"]
+nal = [ 
+    "embedded-time", "embedded-nal", "heapless",
+    "smoltcp-phy", "smoltcp/socket-tcp", "smoltcp/ethernet"
+]
 cortex-m-cpu = ["cortex-m"]
+# Example-based features
+smoltcp-examples = [
+    "smoltcp-phy", "smoltcp/socket-tcp", "smoltcp/ethernet"
+]
+tx_stm32f407 = [
+    "stm32f4xx-hal/stm32f407", "cortex-m", "cortex-m-rtic", "cortex-m-cpu",
+    "panic-itm", "log"
+]
+tcp_stm32f407 = [
+    "stm32f4xx-hal/stm32f407", "cortex-m", "cortex-m-rt", "cortex-m-rtic", "cortex-m-cpu",
+    "smoltcp-examples", "panic-itm", "log"]
 default = []
 
 [[example]]
 name = "tx_stm32f407"
-required-features = ["smoltcp", "cortex-m-cpu"]
+required-features = ["tx_stm32f407"]
 
 [[example]]
 name = "tcp_stm32f407"
-required-features = ["smoltcp", "cortex-m-cpu"]
+required-features = ["tcp_stm32f407"]
 
 [profile.release]
 codegen-units = 1

examples/tcp_stm32f407.rs

@@ -2,31 +2,42 @@
 #![no_main]
 
 extern crate panic_itm;
-use cortex_m::{iprint, iprintln};
+use cortex_m::{iprintln, iprint};
 
-use embedded_hal::{blocking::delay::DelayMs, digital::v2::OutputPin};
-use enc424j600::smoltcp_phy;
-use stm32f4xx_hal::{
-    delay::Delay, gpio::GpioExt, rcc::RccExt, spi::Spi, stm32::ITM, time::Hertz, time::U32Ext,
+use embedded_hal::{
+    digital::v2::OutputPin,
+    blocking::delay::DelayMs
 };
+use stm32f4xx_hal::{
+    rcc::RccExt,
+    gpio::GpioExt,
+    time::U32Ext,
+    stm32::ITM,
+    delay::Delay,
+    spi::Spi,
+    time::Hertz
+};
+use enc424j600::smoltcp_phy;
 
-use core::fmt::Write;
-use core::str;
-use smoltcp::iface::{EthernetInterface, EthernetInterfaceBuilder, NeighborCache};
+use smoltcp::wire::{
+    EthernetAddress, IpAddress, IpCidr, Ipv6Cidr
+};
+use smoltcp::iface::{NeighborCache, EthernetInterfaceBuilder, EthernetInterface};
 use smoltcp::socket::{SocketSet, TcpSocket, TcpSocketBuffer};
-use smoltcp::wire::{EthernetAddress, IpAddress, IpCidr, Ipv6Cidr};
+use core::str;
+use core::fmt::Write;
 
 /// Timer
 use core::cell::RefCell;
 use cortex_m::interrupt::Mutex;
 use cortex_m_rt::exception;
-use smoltcp::time::Instant;
 use stm32f4xx_hal::{
     rcc::Clocks,
-    stm32::SYST,
     time::MilliSeconds,
-    timer::{Event as TimerEvent, Timer},
+    timer::{Timer, Event as TimerEvent},
+    stm32::SYST
 };
+use smoltcp::time::Instant;
 /// Rate in Hz
 const TIMER_RATE: u32 = 20;
 /// Interval duration in milliseconds
@@ -44,34 +55,31 @@ fn timer_setup(syst: SYST, clocks: Clocks) {
 #[exception]
 fn SysTick() {
     cortex_m::interrupt::free(|cs| {
-        *TIMER_MS.borrow(cs).borrow_mut() += TIMER_DELTA;
+        *TIMER_MS.borrow(cs)
+            .borrow_mut() += TIMER_DELTA;
     });
 }
 
 /// Obtain current time in milliseconds
 pub fn timer_now() -> MilliSeconds {
-    let ms = cortex_m::interrupt::free(|cs| *TIMER_MS.borrow(cs).borrow());
+    let ms = cortex_m::interrupt::free(|cs| {
+        *TIMER_MS.borrow(cs)
+            .borrow()
+    });
     ms.ms()
 }
 
 ///
 use stm32f4xx_hal::{
-    gpio::{
-        gpioa::{PA4, PA5, PA6, PA7},
-        Alternate, Output, PushPull, AF5,
-    },
     stm32::SPI1,
+    gpio::{
+        gpioa::{PA5, PA6, PA7, PA4},
+        Alternate, AF5, Output, PushPull
+    }
 };
 type SpiEth = enc424j600::Enc424j600<
-    Spi<
-        SPI1,
-        (
-            PA5<Alternate<AF5>>,
-            PA6<Alternate<AF5>>,
-            PA7<Alternate<AF5>>,
-        ),
-    >,
-    PA4<Output<PushPull>>,
+    Spi<SPI1, (PA5<Alternate<AF5>>, PA6<Alternate<AF5>>, PA7<Alternate<AF5>>)>,
+    PA4<Output<PushPull>>
 >;
 
 pub struct NetStorage {
@@ -81,15 +89,19 @@ pub struct NetStorage {
 
 static mut NET_STORE: NetStorage = NetStorage {
     // Placeholder for the real IP address, which is initialized at runtime.
-    ip_addrs: [IpCidr::Ipv6(Ipv6Cidr::SOLICITED_NODE_PREFIX)],
+    ip_addrs: [IpCidr::Ipv6(
+        Ipv6Cidr::SOLICITED_NODE_PREFIX,
+    )],
     neighbor_cache: [None; 8],
 };
 
 #[rtic::app(device = stm32f4xx_hal::stm32, peripherals = true, monotonic = rtic::cyccnt::CYCCNT)]
 const APP: () = {
     struct Resources {
-        eth_iface: EthernetInterface<'static, smoltcp_phy::SmoltcpDevice<SpiEth>>,
-        itm: ITM,
+        eth_iface: EthernetInterface<
+            'static,
+            smoltcp_phy::SmoltcpDevice<SpiEth>>,
+        itm: ITM
     }
 
     #[init()]
@@ -101,14 +113,11 @@ const APP: () = {
         c.core.DWT.enable_cycle_counter();
         c.core.DCB.enable_trace();
 
-        let clocks = c
-            .device
-            .RCC
-            .constrain()
+        let clocks = c.device.RCC.constrain()
             .cfgr
             .sysclk(168.mhz())
             .hclk(168.mhz())
-            .pclk1(42.mhz())
+            .pclk2(42.mhz())        // used by SPI1
             .require_pll48clk()
             .freeze();
         let mut delay = Delay::new(c.core.SYST, clocks);
@@ -117,7 +126,8 @@ const APP: () = {
         let mut itm = c.core.ITM;
         let stim0 = &mut itm.stim[0];
 
-        iprintln!(stim0, "Eth TCP Server on STM32-F407 via NIC100/ENC424J600");
+        iprintln!(stim0,
+            "Eth TCP Server on STM32-F407 via NIC100/ENC424J600");
 
         // NIC100 / ENC424J600 Set-up
         let spi1 = c.device.SPI1;
@@ -137,14 +147,13 @@ const APP: () = {
         let eth_iface = {
             let mut spi_eth = {
                 let spi_eth_port = Spi::spi1(
-                    spi1,
-                    (spi1_sck, spi1_miso, spi1_mosi),
+                    spi1, (spi1_sck, spi1_miso, spi1_mosi),
                     enc424j600::spi::interfaces::SPI_MODE,
-                    Hertz(enc424j600::spi::interfaces::SPI_CLOCK_FREQ),
-                    clocks,
-                );
+                    10_500_000.hz(),    // PCLK2 @ 42MHz, set SPI1 baud rate as f_PCLK2 divided by 4
+                    clocks);
 
-                SpiEth::new(spi_eth_port, spi1_nss).cpu_freq_mhz(168)
+                SpiEth::new(spi_eth_port, spi1_nss)
+                    .cpu_freq_mhz(168)
             };
 
             // Init controller
@@ -166,7 +175,7 @@ const APP: () = {
                     0 => iprint!(stim0, "MAC Address = {:02x}-", byte),
                     1..=4 => iprint!(stim0, "{:02x}-", byte),
                     5 => iprint!(stim0, "{:02x}\n", byte),
-                    _ => (),
+                _ => ()
                 };
             }
 
@@ -199,7 +208,10 @@ const APP: () = {
         timer_setup(delay.free(), clocks);
         iprintln!(stim0, "Timer initialized");
 
-        init::LateResources { eth_iface, itm }
+        init::LateResources {
+            eth_iface,
+            itm
+        }
     }
 
     #[idle(resources=[eth_iface, itm])]
@@ -229,11 +241,8 @@ const APP: () = {
         let greet_handle = socket_set.add(greet_socket);
         {
             let store = unsafe { &mut NET_STORE };
-            iprintln!(
-                stim0,
-                "TCP sockets will listen at {}",
-                store.ip_addrs[0].address()
-            );
+            iprintln!(stim0,
+                "TCP sockets will listen at {}", store.ip_addrs[0].address());
         }
 
         // Copied / modified from:
@@ -245,7 +254,8 @@ const APP: () = {
             let now = timer_now().0;
             let instant = Instant::from_millis(now as i64);
             match iface.poll(&mut socket_set, instant) {
-                Ok(_) => {}
+                Ok(_) => {
+                },
                 Err(e) => {
                     iprintln!(stim0, "[{}] Poll error: {:?}", instant, e)
                 }
@@ -254,40 +264,33 @@ const APP: () = {
             {
                 let mut socket = socket_set.get::<TcpSocket>(echo_handle);
                 if !socket.is_open() {
-                    iprintln!(
-                        stim0,
-                        "[{}] Listening to port 1234 for echoing, time-out in 10s",
-                        instant
-                    );
+                    iprintln!(stim0,
+                        "[{}] Listening to port 1234 for echoing, time-out in 10s", instant);
                     socket.listen(1234).unwrap();
                     socket.set_timeout(Some(smoltcp::time::Duration::from_millis(10000)));
                 }
                 if socket.can_recv() {
-                    iprintln!(
-                        stim0,
-                        "[{}] Received packet: {:?}",
-                        instant,
-                        socket.recv(|buffer| { (buffer.len(), str::from_utf8(buffer).unwrap()) })
-                    );
+                    iprintln!(stim0,
+                    "[{}] Received packet: {:?}", instant, socket.recv(|buffer| {
+                        (buffer.len(), str::from_utf8(buffer).unwrap())
+                    }));
                 }
             }
             // Control the "greeting" socket (:4321)
             {
                 let mut socket = socket_set.get::<TcpSocket>(greet_handle);
                 if !socket.is_open() {
-                    iprintln!(
-                        stim0,
+                    iprintln!(stim0,
                         "[{}] Listening to port 4321 for greeting, \
-                        please connect to the port",
-                        instant
-                    );
+                        please connect to the port", instant);
                     socket.listen(4321).unwrap();
                 }
 
                 if socket.can_send() {
                     let greeting = "Welcome to the server demo for STM32-F407!";
                     write!(socket, "{}\n", greeting).unwrap();
-                    iprintln!(stim0, "[{}] Greeting sent, socket closed", instant);
+                    iprintln!(stim0,
+                        "[{}] Greeting sent, socket closed", instant);
                     socket.close();
                 }
             }

examples/tx_stm32f407.rs

@@ -2,32 +2,34 @@
 #![no_main]
 
 extern crate panic_itm;
-use cortex_m::{iprint, iprintln};
+use cortex_m::{iprintln, iprint};
 
-use embedded_hal::{blocking::delay::DelayMs, digital::v2::OutputPin};
-use enc424j600::EthPhy;
-use stm32f4xx_hal::{
-    delay::Delay, gpio::GpioExt, rcc::RccExt, spi::Spi, stm32::ITM, time::Hertz, time::U32Ext,
+use embedded_hal::{
+    digital::v2::OutputPin,
+    blocking::delay::DelayMs
 };
+use stm32f4xx_hal::{
+    rcc::RccExt,
+    gpio::GpioExt,
+    time::U32Ext,
+    stm32::ITM,
+    delay::Delay,
+    spi::Spi,
+    time::Hertz
+};
+use enc424j600::EthPhy;
 
 ///
 use stm32f4xx_hal::{
-    gpio::{
-        gpioa::{PA4, PA5, PA6, PA7},
-        Alternate, Output, PushPull, AF5,
-    },
     stm32::SPI1,
+    gpio::{
+        gpioa::{PA5, PA6, PA7, PA4},
+        Alternate, AF5, Output, PushPull
+    },
 };
 type SpiEth = enc424j600::Enc424j600<
-    Spi<
-        SPI1,
-        (
-            PA5<Alternate<AF5>>,
-            PA6<Alternate<AF5>>,
-            PA7<Alternate<AF5>>,
-        ),
-    >,
-    PA4<Output<PushPull>>,
+    Spi<SPI1, (PA5<Alternate<AF5>>, PA6<Alternate<AF5>>, PA7<Alternate<AF5>>)>,
+    PA4<Output<PushPull>>
 >;
 
 #[rtic::app(device = stm32f4xx_hal::stm32, peripherals = true, monotonic = rtic::cyccnt::CYCCNT)]
@@ -43,16 +45,11 @@ const APP: () = {
         c.core.SCB.enable_icache();
         c.core.SCB.enable_dcache(&mut c.core.CPUID);
 
-        let clocks = c
-            .device
-            .RCC
-            .constrain()
+        let clocks = c.device.RCC.constrain()
             .cfgr
             .sysclk(168.mhz())
             .hclk(168.mhz())
-            //.pclk1(32.mhz())
-            .pclk1(42.mhz())
-            //.pclk2(64.mhz())
+            .pclk2(42.mhz())        // used by SPI1
             .require_pll48clk()
             .freeze();
         let mut delay = Delay::new(c.core.SYST, clocks);
@@ -60,7 +57,8 @@ const APP: () = {
         // Init ITM
         let mut itm = c.core.ITM;
         let stim0 = &mut itm.stim[0];
-        iprintln!(stim0, "Eth TX Pinging on STM32-F407 via NIC100/ENC424J600");
+        iprintln!(stim0,
+            "Eth TX Pinging on STM32-F407 via NIC100/ENC424J600");
 
         // NIC100 / ENC424J600 Set-up
         let spi1 = c.device.SPI1;
@@ -78,14 +76,13 @@ const APP: () = {
         // Create SPI1 for HAL
         let mut spi_eth = {
             let spi_eth_port = Spi::spi1(
-                spi1,
-                (spi1_sck, spi1_miso, spi1_mosi),
+                spi1, (spi1_sck, spi1_miso, spi1_mosi),
                 enc424j600::spi::interfaces::SPI_MODE,
-                Hertz(enc424j600::spi::interfaces::SPI_CLOCK_FREQ),
-                clocks,
-            );
+                10_500_000.hz(),    // PCLK2 @ 42MHz, set SPI1 baud rate as f_PCLK2 divided by 4
+                clocks);
 
-            SpiEth::new(spi_eth_port, spi1_nss).cpu_freq_mhz(168)
+            SpiEth::new(spi_eth_port, spi1_nss)
+                .cpu_freq_mhz(168)
         };
 
         // Init
@@ -107,7 +104,7 @@ const APP: () = {
                 0 => iprint!(stim0, "MAC Address = {:02x}-", byte),
                 1..=4 => iprint!(stim0, "{:02x}-", byte),
                 5 => iprint!(stim0, "{:02x}\n", byte),
-                _ => (),
+                _ => ()
             };
         }
 
@@ -128,20 +125,20 @@ const APP: () = {
         let stim0 = &mut c.resources.itm.stim[0];
         // Testing Eth TX
         let eth_tx_dat: [u8; 64] = [
-            0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x08, 0x60, 0x6e, 0x44, 0x42, 0x95, 0x08, 0x06,
-            0x00, 0x01, 0x08, 0x00, 0x06, 0x04, 0x00, 0x01, 0x08, 0x60, 0x6e, 0x44, 0x42, 0x95,
-            0xc0, 0xa8, 0x01, 0x64, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0xa8, 0x01, 0xe7,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x69, 0xd0, 0x85, 0x9f,
+            0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x08, 0x60,
+            0x6e, 0x44, 0x42, 0x95, 0x08, 0x06, 0x00, 0x01,
+            0x08, 0x00, 0x06, 0x04, 0x00, 0x01, 0x08, 0x60,
+            0x6e, 0x44, 0x42, 0x95, 0xc0, 0xa8, 0x01, 0x64,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0xa8,
+            0x01, 0xe7, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x69, 0xd0, 0x85, 0x9f
         ];
         loop {
             let mut eth_tx_packet = enc424j600::tx::TxPacket::new();
             eth_tx_packet.update_frame(&eth_tx_dat, 64);
-            iprint!(
-                stim0,
-                "Sending packet (len={:}): ",
-                eth_tx_packet.get_frame_length()
-            );
+            iprint!(stim0,
+                "Sending packet (len={:}): ", eth_tx_packet.get_frame_length());
             for i in 0..20 {
                 let byte = eth_tx_packet.get_frame_byte(i);
                 match i {
@@ -152,7 +149,7 @@ const APP: () = {
                     13..=14 | 16..=18 => iprint!(stim0, "{:02x}", byte),
                     5 | 11 | 15 => iprint!(stim0, "{:02x} ", byte),
                     19 => iprint!(stim0, "{:02x} ...\n", byte),
-                    _ => (),
+                    _ => ()
                 };
             }
             c.resources.spi_eth.send_packet(&eth_tx_packet);

src/lib.rs

@@ -2,16 +2,22 @@
 
 pub mod spi;
 use embedded_hal::{
-    blocking::{delay::DelayUs, spi::Transfer},
+    blocking::{
+        spi::Transfer,
+        delay::DelayUs,
+    },
     digital::v2::OutputPin,
 };
 
 pub mod rx;
 pub mod tx;
 
-#[cfg(feature = "smoltcp")]
+#[cfg(feature="smoltcp")]
 pub mod smoltcp_phy;
 
+#[cfg(feature="nal")]
+pub mod nal;
+
 /// Max raw frame array size
 pub const RAW_FRAME_LENGTH_MAX: usize = 1518;
 
@@ -27,7 +33,7 @@ pub enum Error {
     SpiPortError,
     RegisterError,
     // TODO: Better name?
-    NoRxPacketError,
+    NoRxPacketError
 }
 
 impl From<spi::Error> for Error {
@@ -37,13 +43,15 @@ impl From<spi::Error> for Error {
 }
 
 /// ENC424J600 controller in SPI mode
-pub struct Enc424j600<SPI: Transfer<u8>, NSS: OutputPin> {
+pub struct Enc424j600<SPI: Transfer<u8>,
+                      NSS: OutputPin> {
     spi_port: spi::SpiPort<SPI, NSS>,
     rx_buf: rx::RxBuffer,
     tx_buf: tx::TxBuffer,
 }
 
-impl<SPI: Transfer<u8>, NSS: OutputPin> Enc424j600<SPI, NSS> {
+impl <SPI: Transfer<u8>,
+      NSS: OutputPin> Enc424j600<SPI, NSS> {
     pub fn new(spi: SPI, nss: NSS) -> Self {
         Enc424j600 {
             spi_port: spi::SpiPort::new(spi, nss),
@@ -71,14 +79,12 @@ impl<SPI: Transfer<u8>, NSS: OutputPin> Enc424j600<SPI, NSS> {
         // Verify that EUDAST is 0x1234
         let mut eudast = self.spi_port.read_reg_16b(spi::addrs::EUDAST)?;
         if eudast != 0x1234 {
-            return Err(Error::RegisterError);
+            return Err(Error::RegisterError)
         }
         // Poll CLKRDY (ESTAT<12>) to check if it is set
         loop {
             let estat = self.spi_port.read_reg_16b(spi::addrs::ESTAT)?;
-            if estat & 0x1000 == 0x1000 {
-                break;
-            }
+            if estat & 0x1000 == 0x1000 { break }
         }
         // Issue system reset - set ETHRST (ECON2<4>) to 1
         self.spi_port.send_opcode(spi::opcodes::SETETHRST)?;
@@ -86,7 +92,7 @@ impl<SPI: Transfer<u8>, NSS: OutputPin> Enc424j600<SPI, NSS> {
         // Verify that EUDAST is 0x0000
         eudast = self.spi_port.read_reg_16b(spi::addrs::EUDAST)?;
         if eudast != 0x0000 {
-            return Err(Error::RegisterError);
+            return Err(Error::RegisterError)
         }
         delay.delay_us(256);
         Ok(())
@@ -94,14 +100,11 @@ impl<SPI: Transfer<u8>, NSS: OutputPin> Enc424j600<SPI, NSS> {
 
     pub fn init_rxbuf(&mut self) -> Result<(), Error> {
         // Set ERXST pointer
-        self.spi_port
-            .write_reg_16b(spi::addrs::ERXST, self.rx_buf.get_start_addr())?;
+        self.spi_port.write_reg_16b(spi::addrs::ERXST, self.rx_buf.get_start_addr())?;
         // Set ERXTAIL pointer
-        self.spi_port
-            .write_reg_16b(spi::addrs::ERXTAIL, self.rx_buf.get_tail_addr())?;
+        self.spi_port.write_reg_16b(spi::addrs::ERXTAIL, self.rx_buf.get_tail_addr())?;
         // Set MAMXFL to maximum number of bytes in each accepted packet
-        self.spi_port
-            .write_reg_16b(spi::addrs::MAMXFL, RAW_FRAME_LENGTH_MAX as u16)?;
+        self.spi_port.write_reg_16b(spi::addrs::MAMXFL, RAW_FRAME_LENGTH_MAX as u16)?;
         // Enable RX - set RXEN (ECON1<0>) to 1
         self.spi_port.send_opcode(spi::opcodes::ENABLERX)?;
         Ok(())
@@ -119,10 +122,7 @@ impl<SPI: Transfer<u8>, NSS: OutputPin> Enc424j600<SPI, NSS> {
         // "To accept all incoming frames regardless of content (Promiscuous mode),
         // set the CRCEN, RUNTEN, UCEN, NOTMEEN and MCEN bits."
         let erxfcon_lo = self.spi_port.read_reg_8b(spi::addrs::ERXFCON)?;
-        self.spi_port.write_reg_8b(
-            spi::addrs::ERXFCON,
-            0b0101_1110 | (erxfcon_lo & 0b1010_0001),
-        )?;
+        self.spi_port.write_reg_8b(spi::addrs::ERXFCON, 0b0101_1110 | (erxfcon_lo & 0b1010_0001))?;
         Ok(())
     }
 
@@ -148,7 +148,8 @@ impl<SPI: Transfer<u8>, NSS: OutputPin> Enc424j600<SPI, NSS> {
     }
 }
 
-impl<SPI: Transfer<u8>, NSS: OutputPin> EthPhy for Enc424j600<SPI, NSS> {
+impl <SPI: Transfer<u8>,
+      NSS: OutputPin> EthPhy for Enc424j600<SPI, NSS> {
     /// Receive the next packet and return it
     /// Set is_poll to true for returning until PKTIF is set;
     /// Set is_poll to false for returning Err when PKTIF is not set
@@ -156,21 +157,17 @@ impl<SPI: Transfer<u8>, NSS: OutputPin> EthPhy for Enc424j600<SPI, NSS> {
         // Poll PKTIF (EIR<4>) to check if it is set
         loop {
             let eir = self.spi_port.read_reg_16b(spi::addrs::EIR)?;
-            if eir & 0x40 == 0x40 {
-                break;
-            }
+            if eir & 0x40 == 0x40 { break }
             if !is_poll {
-                return Err(Error::NoRxPacketError);
+                return Err(Error::NoRxPacketError)
             }
         }
         // Set ERXRDPT pointer to next_addr
-        self.spi_port
-            .write_reg_16b(spi::addrs::ERXRDPT, self.rx_buf.get_next_addr())?;
+        self.spi_port.write_reg_16b(spi::addrs::ERXRDPT, self.rx_buf.get_next_addr())?;
         // Read 2 bytes to update next_addr
         let mut next_addr_buf = [0; 3];
         self.spi_port.read_rxdat(&mut next_addr_buf, 2)?;
-        self.rx_buf
-            .set_next_addr((next_addr_buf[1] as u16) | ((next_addr_buf[2] as u16) << 8));
+        self.rx_buf.set_next_addr((next_addr_buf[1] as u16) | ((next_addr_buf[2] as u16) << 8));
         // Read 6 bytes to update rsv
         let mut rsv_buf = [0; 7];
         self.spi_port.read_rxdat(&mut rsv_buf, 6)?;
@@ -182,19 +179,16 @@ impl<SPI: Transfer<u8>, NSS: OutputPin> EthPhy for Enc424j600<SPI, NSS> {
         rx_packet.update_frame_length();
         // Read frame bytes
         let mut frame_buf = [0; RAW_FRAME_LENGTH_MAX];
-        self.spi_port
-            .read_rxdat(&mut frame_buf, rx_packet.get_frame_length())?;
+        self.spi_port.read_rxdat(&mut frame_buf, rx_packet.get_frame_length())?;
         rx_packet.copy_frame_from(&frame_buf[1..]);
         // Set ERXTAIL pointer to (next_addr - 2)
         // * Assume head, tail, next and wrap addresses are word-aligned (even)
         // - If next_addr is at least (start_addr+2), then set tail pointer to the word right before next_addr
         if self.rx_buf.get_next_addr() > self.rx_buf.get_start_addr() {
-            self.spi_port
-                .write_reg_16b(spi::addrs::ERXTAIL, self.rx_buf.get_next_addr() - 2)?;
+            self.spi_port.write_reg_16b(spi::addrs::ERXTAIL, self.rx_buf.get_next_addr() - 2)?;
         // - Otherwise, next_addr will wrap, so set tail pointer to the last word address of RX buffer
         } else {
-            self.spi_port
-                .write_reg_16b(spi::addrs::ERXTAIL, rx::RX_MAX_ADDRESS - 1)?;
+            self.spi_port.write_reg_16b(spi::addrs::ERXTAIL, rx::RX_MAX_ADDRESS - 1)?;
         }
         // Decrement PKTCNT - set PKTDEC (ECON1<8>)
         self.spi_port.send_opcode(spi::opcodes::SETPKTDEC)?;
@@ -205,38 +199,29 @@ impl<SPI: Transfer<u8>, NSS: OutputPin> EthPhy for Enc424j600<SPI, NSS> {
     /// Send an established packet
     fn send_packet(&mut self, packet: &tx::TxPacket) -> Result<(), Error> {
         // Set EGPWRPT pointer to next_addr
-        self.spi_port
-            .write_reg_16b(spi::addrs::EGPWRPT, self.tx_buf.get_next_addr())?;
+        self.spi_port.write_reg_16b(spi::addrs::EGPWRPT, self.tx_buf.get_next_addr())?;
         // Copy packet data to SRAM Buffer
         // 1-byte Opcode is included
         let mut txdat_buf: [u8; RAW_FRAME_LENGTH_MAX + 1] = [0; RAW_FRAME_LENGTH_MAX + 1];
         packet.write_frame_to(&mut txdat_buf[1..]);
-        self.spi_port
-            .write_txdat(&mut txdat_buf, packet.get_frame_length())?;
+        self.spi_port.write_txdat(&mut txdat_buf, packet.get_frame_length())?;
         // Set ETXST to packet start address
-        self.spi_port
-            .write_reg_16b(spi::addrs::ETXST, self.tx_buf.get_next_addr())?;
+        self.spi_port.write_reg_16b(spi::addrs::ETXST, self.tx_buf.get_next_addr())?;
         // Set ETXLEN to packet length
-        self.spi_port
-            .write_reg_16b(spi::addrs::ETXLEN, packet.get_frame_length() as u16)?;
+        self.spi_port.write_reg_16b(spi::addrs::ETXLEN, packet.get_frame_length() as u16)?;
         // Send packet - set TXRTS (ECON1<1>) to start transmission
         self.spi_port.send_opcode(spi::opcodes::SETTXRTS)?;
         // Poll TXRTS (ECON1<1>) to check if it is reset
         loop {
             let econ1_lo = self.spi_port.read_reg_8b(spi::addrs::ECON1)?;
-            if econ1_lo & 0x02 == 0 {
-                break;
-            }
+            if econ1_lo & 0x02 == 0 { break }
         }
         // TODO: Read ETXSTAT to understand Ethernet transmission status
         // (See: Register 9-2, ENC424J600 Data Sheet)
         // Update TX buffer start address
         // * Assume TX buffer consumes the entire general-purpose SRAM block
-        self.tx_buf.set_next_addr(
-            (self.tx_buf.get_next_addr() + packet.get_frame_length() as u16)
-                % self.rx_buf.get_start_addr()
-                - self.tx_buf.get_start_addr(),
-        );
+        self.tx_buf.set_next_addr((self.tx_buf.get_next_addr() + packet.get_frame_length() as u16) %
+            self.rx_buf.get_start_addr() - self.tx_buf.get_start_addr());
         Ok(())
     }
 }

src/nal.rs

@@ -0,0 +1,314 @@
+use core::cell::RefCell;
+use core::convert::TryInto;
+use heapless::{consts, Vec};
+use embedded_nal as nal;
+use nal::nb;
+use smoltcp as net;
+use embedded_hal::{
+    blocking::spi::Transfer,
+    digital::v2::OutputPin
+};
+pub use embedded_time as time;
+use time::duration::*;
+
+#[derive(Debug)]
+pub enum NetworkError {
+    NoSocket,
+    ConnectionFailure,
+    ReadFailure,
+    WriteFailure,
+    Unsupported,
+    TimeFault,
+}
+
+pub type NetworkInterface<SPI, NSS> = net::iface::EthernetInterface<
+    'static,
+    crate::smoltcp_phy::SmoltcpDevice<
+        crate::Enc424j600<SPI, NSS>
+    >,
+>;
+
+pub struct NetworkStack<'a, SPI, NSS, IntClock>
+where
+    SPI: 'static + Transfer<u8>,
+    NSS: 'static + OutputPin,
+    IntClock: time::Clock<T = u32>,
+{
+    network_interface: RefCell<NetworkInterface<SPI, NSS>>,
+    sockets: RefCell<net::socket::SocketSet<'a>>,
+    next_port: RefCell<u16>,
+    unused_handles: RefCell<Vec<net::socket::SocketHandle, consts::U16>>,
+    time_ms: RefCell<u32>,
+    last_update_instant: RefCell<Option<time::Instant<IntClock>>>,
+    clock: IntClock,
+    connection_timeout_ms: u32,
+}
+
+impl<'a, SPI, NSS, IntClock> NetworkStack<'a, SPI, NSS, IntClock>
+where
+    SPI: Transfer<u8>,
+    NSS: OutputPin,
+    IntClock: time::Clock<T = u32>,
+{
+    pub fn new(
+        interface: NetworkInterface<SPI, NSS>,
+        sockets: net::socket::SocketSet<'a>,
+        clock: IntClock,
+        connection_timeout_ms: u32,
+    ) -> Self {
+        let mut unused_handles: Vec<net::socket::SocketHandle, consts::U16> = Vec::new();
+        for socket in sockets.iter() {
+            unused_handles.push(socket.handle()).unwrap();
+        }
+        NetworkStack {
+            network_interface: RefCell::new(interface),
+            sockets: RefCell::new(sockets),
+            next_port: RefCell::new(49152),
+            unused_handles: RefCell::new(unused_handles),
+            time_ms: RefCell::new(0),
+            last_update_instant: RefCell::new(None),
+            clock,
+            connection_timeout_ms,
+        }
+    }
+
+    // Initiate or advance the timer, and return the duration in ms as u32.
+    fn update(&self) -> Result<u32, NetworkError> {
+        let mut duration_ms: u32 = 0;
+        // Check if it is the first time the stack has updated the time itself
+        let now = match *self.last_update_instant.borrow() {
+            // If it is the first time, do not advance time
+            // Simply store the current instant to initiate time updating
+            None => self.clock.try_now().map_err(|_| NetworkError::TimeFault)?,
+            // If it was updated before, advance time and update last_update_instant
+            Some(instant) => {
+                // Calculate elapsed time
+                let now = self.clock.try_now().map_err(|_| NetworkError::TimeFault)?;
+                let mut duration = now.checked_duration_since(&instant);
+                // Normally, the wrapping clock should produce a valid duration.
+                // However, if `now` is earlier than `instant` (e.g. because the main 
+                // application cannot get a valid epoch time during initialisation, 
+                // we should still produce a duration that is just 1ms.
+                if duration.is_none() {
+                    self.time_ms.replace(0);
+                    duration = Some(Milliseconds(1_u32)
+                        .to_generic::<u32>(IntClock::SCALING_FACTOR)
+                        .map_err(|_| NetworkError::TimeFault)?);
+                }
+                let duration_ms_time: Milliseconds<u32> = duration.unwrap().try_into()
+                    .map_err(|_| NetworkError::TimeFault)?;
+                duration_ms = *duration_ms_time.integer();
+                // Adjust duration into ms (note: decimal point truncated)
+                self.advance_time(duration_ms);
+                now
+            }
+        };
+        self.last_update_instant.replace(Some(now));
+        Ok(duration_ms)
+    }
+
+    fn advance_time(&self, duration_ms: u32) {
+        let time = self.time_ms.borrow().wrapping_add(duration_ms);
+        self.time_ms.replace(time);
+    }
+
+    // Poll on the smoltcp interface
+    fn poll(&self) -> Result<bool, NetworkError> {
+        match self.network_interface.borrow_mut().poll(
+            &mut self.sockets.borrow_mut(),
+            net::time::Instant::from_millis(*self.time_ms.borrow() as u32),
+        ) {
+            Ok(changed) => Ok(!changed),
+            Err(_e) => {
+                Ok(true)
+            }
+        }
+    }
+
+    fn get_ephemeral_port(&self) -> u16 {
+        // Get the next ephemeral port
+        let current_port = self.next_port.borrow().clone();
+        let (next, wrap) = self.next_port.borrow().overflowing_add(1);
+        *self.next_port.borrow_mut() = if wrap { 49152 } else { next };
+        return current_port;
+    }
+}
+impl<'a, SPI, NSS, IntClock> nal::TcpStack for NetworkStack<'a, SPI, NSS, IntClock>
+where
+    SPI: Transfer<u8>,
+    NSS: OutputPin,
+    IntClock: time::Clock<T = u32>,
+{
+    type TcpSocket = net::socket::SocketHandle;
+    type Error = NetworkError;
+    fn open(&self, _mode: nal::Mode) -> Result<Self::TcpSocket, Self::Error> {
+        match self.unused_handles.borrow_mut().pop() {
+            Some(handle) => {
+                // Abort any active connections on the handle.
+                let mut sockets = self.sockets.borrow_mut();
+                let socket: &mut net::socket::TcpSocket = &mut *sockets.get(handle);
+                socket.abort();
+                Ok(handle)
+            }
+            None => Err(NetworkError::NoSocket),
+        }
+    }
+
+    fn connect(
+        &self,
+        handle: Self::TcpSocket,
+        remote: nal::SocketAddr,
+    ) -> Result<Self::TcpSocket, Self::Error> {
+        {
+            // If the socket has already been connected, ignore the connection
+            // request silently.
+            let mut sockets = self.sockets.borrow_mut();
+            let socket: &mut net::socket::TcpSocket = &mut *sockets.get(handle);
+            if socket.state() == net::socket::TcpState::Established {
+                return Ok(handle)
+            }
+        }
+
+        {
+            let mut sockets = self.sockets.borrow_mut();
+            let socket: &mut net::socket::TcpSocket = &mut *sockets.get(handle);
+            // abort() instead of close() prevents TcpSocket::connect() from
+            // raising an error
+            socket.abort();
+            match remote.ip() {
+                nal::IpAddr::V4(addr) => {
+                    let address =
+                        net::wire::Ipv4Address::from_bytes(&addr.octets()[..]);
+                    socket
+                        .connect((address, remote.port()), self.get_ephemeral_port())
+                        .map_err(|_| NetworkError::ConnectionFailure)?;
+                    net::wire::IpAddress::Ipv4(address)
+                },
+                nal::IpAddr::V6(addr) => {
+                    let address =
+                        net::wire::Ipv6Address::from_parts(&addr.segments()[..]);
+                    socket
+                        .connect((address, remote.port()), self.get_ephemeral_port())
+                        .map_err(|_| NetworkError::ConnectionFailure)?;
+                    net::wire::IpAddress::Ipv6(address)
+                }
+            }
+        };
+        // Blocking connect
+        // Loop to wait until the socket is staying established or closed,
+        // or the connection attempt has timed out.
+        let mut timeout_ms: u32 = 0;
+        loop {
+            {
+                let mut sockets = self.sockets.borrow_mut();
+                let socket: &mut net::socket::TcpSocket = &mut *sockets.get(handle);
+                // TCP state at ESTABLISHED means there is connection, so
+                // simply return the socket.
+                if socket.state() == net::socket::TcpState::Established {
+                    return Ok(handle)
+                }
+                // TCP state at CLOSED implies that the remote rejected connection;
+                // In this case, abort the connection, and then return the socket
+                // for re-connection in the future.
+                if socket.state() == net::socket::TcpState::Closed {
+                    socket.abort();
+                    // TODO: Return Err(), but would require changes in quartiq/minimq
+                    return Ok(handle)
+                }
+            }
+            
+            // Any TCP states other than CLOSED and ESTABLISHED are considered
+            // "transient", so this function should keep waiting and let smoltcp poll
+            // (e.g. for handling echo reqeust/reply) at the same time.
+            timeout_ms += self.update()?;
+            self.poll()?;
+
+            // Time out, and return the socket for re-connection in the future.
+            if timeout_ms > self.connection_timeout_ms {
+                // TODO: Return Err(), but would require changes in quartiq/minimq
+                return Ok(handle)
+            }
+        }
+    }
+
+    fn is_connected(&self, handle: &Self::TcpSocket) -> Result<bool, Self::Error> {
+        let mut sockets = self.sockets.borrow_mut();
+        let socket: &mut net::socket::TcpSocket = &mut *sockets.get(*handle);
+        Ok(socket.state() == net::socket::TcpState::Established)
+    }
+
+    fn write(&self, handle: &mut Self::TcpSocket, buffer: &[u8]) -> nb::Result<usize, Self::Error> {
+        let mut write_error = false;
+        let mut non_queued_bytes = &buffer[..];
+        while non_queued_bytes.len() != 0 {
+            let result = {
+                let mut sockets = self.sockets.borrow_mut();
+                let socket: &mut net::socket::TcpSocket = &mut *sockets.get(*handle);
+                let result = socket.send_slice(non_queued_bytes);
+                result
+            };
+            match result {
+                Ok(num_bytes) => {
+                    // If the buffer is completely filled, close the socket and
+                    // return an error
+                    if num_bytes == 0 {
+                        write_error = true;
+                        break;
+                    }
+                    // In case the buffer is filled up, push bytes into ethernet driver
+                    if num_bytes != non_queued_bytes.len() {
+                        self.update()?;
+                        self.poll()?;
+                    }
+                    // Process the unwritten bytes again, if any
+                    non_queued_bytes = &non_queued_bytes[num_bytes..]
+                }
+                Err(_) => {
+                    write_error = true;
+                    break;
+                }
+            }
+        }
+        if write_error {
+            // Close the socket to push it back to the array, for
+            // re-opening the socket in the future
+            self.close(*handle)?;
+            return Err(nb::Error::Other(NetworkError::WriteFailure))
+        }   
+        Ok(buffer.len())
+    }
+
+    fn read(
+        &self,
+        handle: &mut Self::TcpSocket,
+        buffer: &mut [u8],
+    ) -> nb::Result<usize, Self::Error> {
+        // Enqueue received bytes into the TCP socket buffer
+        self.update()?;
+        self.poll()?;
+        {
+            let mut sockets = self.sockets.borrow_mut();
+            let socket: &mut net::socket::TcpSocket = &mut *sockets.get(*handle);
+            let result = socket.recv_slice(buffer);
+            match result {
+                Ok(num_bytes) => { return Ok(num_bytes) },
+                Err(_) => {},
+            }
+        }
+        // Close the socket to push it back to the array, for
+        // re-opening the socket in the future
+        self.close(*handle)?;
+        Err(nb::Error::Other(NetworkError::ReadFailure))
+    }
+
+    fn close(&self, handle: Self::TcpSocket) -> Result<(), Self::Error> {
+        let mut sockets = self.sockets.borrow_mut();
+        let socket: &mut net::socket::TcpSocket = &mut *sockets.get(handle);
+        socket.close();
+        let mut unused_handles = self.unused_handles.borrow_mut();
+        if unused_handles.iter().find(|&x| *x == handle).is_none() {
+            unused_handles.push(handle).unwrap();
+        }
+        Ok(())
+    }
+}

src/rx.rs

@@ -13,7 +13,7 @@ pub const RSV_LENGTH: usize = 6;
 pub struct RxBuffer {
     start_addr: u16,
     next_addr: u16,
-    tail_addr: u16,
+    tail_addr: u16
 }
 
 impl RxBuffer {
@@ -21,28 +21,28 @@ impl RxBuffer {
         RxBuffer {
             start_addr: ERXST_DEFAULT,
             next_addr: ERXST_DEFAULT,
-            tail_addr: ERXTAIL_DEFAULT,
+            tail_addr: ERXTAIL_DEFAULT
         }
     }
 
     pub fn set_start_addr(&mut self, addr: u16) {
         self.start_addr = addr;
     }
-    pub fn get_start_addr(&self) -> u16 {
+    pub fn get_start_addr(& self) -> u16{
         self.start_addr
     }
 
     pub fn set_next_addr(&mut self, addr: u16) {
         self.next_addr = addr;
     }
-    pub fn get_next_addr(&self) -> u16 {
+    pub fn get_next_addr(& self) -> u16 {
         self.next_addr
     }
 
     pub fn set_tail_addr(&mut self, addr: u16) {
         self.tail_addr = addr;
     }
-    pub fn get_tail_addr(&self) -> u16 {
+    pub fn get_tail_addr(& self) -> u16{
         self.tail_addr
     }
 }
@@ -52,7 +52,7 @@ impl RxBuffer {
 pub struct RxPacket {
     rsv: Rsv,
     frame: [u8; RAW_FRAME_LENGTH_MAX],
-    frame_length: usize,
+    frame_length: usize
 }
 
 impl RxPacket {
@@ -60,7 +60,7 @@ impl RxPacket {
         RxPacket {
             rsv: Rsv::new(),
             frame: [0; RAW_FRAME_LENGTH_MAX],
-            frame_length: 0,
+            frame_length: 0
         }
     }
 
@@ -106,14 +106,14 @@ impl RxPacket {
 struct Rsv {
     raw_rsv: [u8; RSV_LENGTH],
     // TODO: Add more definitions
-    frame_length: u16,
+    frame_length: u16
 }
 
 impl Rsv {
     fn new() -> Self {
         Rsv {
             raw_rsv: [0; RSV_LENGTH],
-            frame_length: 0_u16,
+            frame_length: 0_u16
         }
     }
 

src/smoltcp_phy.rs

@@ -1,15 +1,17 @@
-use crate::{tx, EthPhy, RAW_FRAME_LENGTH_MAX};
+use crate::{
+    EthPhy, tx, RAW_FRAME_LENGTH_MAX
+};
 use core::cell;
 use smoltcp::{
     phy::{Device, DeviceCapabilities, RxToken, TxToken},
     time::Instant,
-    Error,
+    Error
 };
 
 pub struct SmoltcpDevice<E: EthPhy> {
     pub eth_phy: cell::RefCell<E>,
     rx_packet_buf: [u8; RAW_FRAME_LENGTH_MAX],
-    tx_packet_buf: [u8; RAW_FRAME_LENGTH_MAX],
+    tx_packet_buf: [u8; RAW_FRAME_LENGTH_MAX]
 }
 
 impl<E: EthPhy> SmoltcpDevice<E> {
@@ -17,7 +19,7 @@ impl<E: EthPhy> SmoltcpDevice<E> {
         SmoltcpDevice {
             eth_phy: cell::RefCell::new(eth_phy),
             rx_packet_buf: [0; RAW_FRAME_LENGTH_MAX],
-            tx_packet_buf: [0; RAW_FRAME_LENGTH_MAX],
+            tx_packet_buf: [0; RAW_FRAME_LENGTH_MAX]
         }
     }
 }
@@ -41,16 +43,16 @@ impl<'a, E: 'a + EthPhy> Device<'a> for SmoltcpDevice<E> {
                 // Construct a RxToken
                 let rx_token = EthRxToken {
                     buf: &mut self.rx_packet_buf,
-                    len: rx_packet.get_frame_length(),
+                    len: rx_packet.get_frame_length()
                 };
                 // Construct a blank TxToken
                 let tx_token = EthTxToken {
                     buf: &mut self.tx_packet_buf,
-                    dev: self_p,
+                    dev: self_p
                 };
                 Some((rx_token, tx_token))
-            }
-            Err(_) => None,
+            },
+            Err(_) => None
         }
     }
 
@@ -59,7 +61,7 @@ impl<'a, E: 'a + EthPhy> Device<'a> for SmoltcpDevice<E> {
         // Construct a blank TxToken
         let tx_token = EthTxToken {
             buf: &mut self.tx_packet_buf,
-            dev: self_p,
+            dev: self_p
         };
         Some(tx_token)
     }
@@ -67,7 +69,7 @@ impl<'a, E: 'a + EthPhy> Device<'a> for SmoltcpDevice<E> {
 
 pub struct EthRxToken<'a> {
     buf: &'a mut [u8],
-    len: usize,
+    len: usize
 }
 
 impl<'a> RxToken for EthRxToken<'a> {
@@ -81,7 +83,7 @@ impl<'a> RxToken for EthRxToken<'a> {
 
 pub struct EthTxToken<'a, E: EthPhy> {
     buf: &'a mut [u8],
-    dev: *mut SmoltcpDevice<E>,
+    dev: *mut SmoltcpDevice<E>
 }
 
 impl<'a, E: 'a + EthPhy> TxToken for EthTxToken<'a, E> {
@@ -95,10 +97,12 @@ impl<'a, E: 'a + EthPhy> TxToken for EthTxToken<'a, E> {
         // Update frame length and write frame bytes
         tx_packet.update_frame(&mut self.buf[..len], len);
         // Send the packet as raw
-        let eth_phy = unsafe { &mut (*self.dev).eth_phy };
+        let eth_phy = unsafe {
+            &mut (*self.dev).eth_phy
+        };
         match eth_phy.borrow_mut().send_packet(&tx_packet) {
-            Ok(_) => result,
-            Err(_) => Err(Error::Exhausted),
+            Ok(_) => { result },
+            Err(_) => Err(Error::Exhausted)
         }
     }
 }

src/spi.rs

@@ -1,4 +1,7 @@
-use embedded_hal::{blocking::spi::Transfer, digital::v2::OutputPin};
+use embedded_hal::{
+    blocking::spi::Transfer,
+    digital::v2::OutputPin,
+};
 
 pub mod interfaces {
     use embedded_hal::spi;
@@ -58,7 +61,8 @@ pub mod addrs {
 
 /// Struct for SPI I/O interface on ENC424J600
 /// Note: stm32f4xx_hal::spi's pins include: SCK, MISO, MOSI
-pub struct SpiPort<SPI: Transfer<u8>, NSS: OutputPin> {
+pub struct SpiPort<SPI: Transfer<u8>,
+                   NSS: OutputPin> {
     spi: SPI,
     nss: NSS,
     #[cfg(feature = "cortex-m-cpu")]
@@ -67,11 +71,12 @@ pub struct SpiPort<SPI: Transfer<u8>, NSS: OutputPin> {
 
 pub enum Error {
     OpcodeError,
-    TransferError,
+    TransferError
 }
 
 #[allow(unused_must_use)]
-impl<SPI: Transfer<u8>, NSS: OutputPin> SpiPort<SPI, NSS> {
+impl <SPI: Transfer<u8>,
+      NSS: OutputPin> SpiPort<SPI, NSS> {
     // TODO: return as Result()
     pub fn new(spi: SPI, mut nss: NSS) -> Self {
         nss.set_high();
@@ -105,7 +110,7 @@ impl<SPI: Transfer<u8>, NSS: OutputPin> SpiPort<SPI, NSS> {
         let mut data_offset = 0;    // number of bytes separating
                                     // actual data from opcode
         match lo_addr {
-            addrs::ERXRDPT | addrs::EGPWRPT => {}
+            addrs::ERXRDPT | addrs::EGPWRPT => { }
             _ => {
                 buf[1] = lo_addr;
                 data_offset = 1;
@@ -116,21 +121,23 @@ impl<SPI: Transfer<u8>, NSS: OutputPin> SpiPort<SPI, NSS> {
             match lo_addr {
                 addrs::ERXRDPT => opcodes::RRXRDPT,
                 addrs::EGPWRPT => opcodes::RGPWRPT,
-                _ => opcodes::RCRU,
+                _ => opcodes::RCRU
             },
-            2 + data_offset, // extra 8-bit lo_addr before data
+            2 + data_offset     // extra 8-bit lo_addr before data
         )?;
-        Ok(buf[data_offset + 1] as u16 | (buf[data_offset + 2] as u16) << 8)
+        Ok(buf[data_offset+1] as u16 | (buf[data_offset+2] as u16) << 8)
     }
 
     // Currently requires manual slicing (buf[1..]) for the data read back
-    pub fn read_rxdat<'a>(&mut self, buf: &'a mut [u8], data_length: usize) -> Result<(), Error> {
+    pub fn read_rxdat<'a>(&mut self, buf: &'a mut [u8], data_length: usize)
+                         -> Result<(), Error> {
         self.rw_n(buf, opcodes::RRXDATA, data_length)
     }
 
     // Currently requires actual data to be stored in buf[1..] instead of buf[0..]
     // TODO: Maybe better naming?
-    pub fn write_txdat<'a>(&mut self, buf: &'a mut [u8], data_length: usize) -> Result<(), Error> {
+    pub fn write_txdat<'a>(&mut self, buf: &'a mut [u8], data_length: usize)
+                          -> Result<(), Error> {
         self.rw_n(buf, opcodes::WGPDATA, data_length)
     }
 
@@ -149,32 +156,33 @@ impl<SPI: Transfer<u8>, NSS: OutputPin> SpiPort<SPI, NSS> {
         let mut data_offset = 0;    // number of bytes separating
                                     // actual data from opcode
         match lo_addr {
-            addrs::ERXRDPT | addrs::EGPWRPT => {}
+            addrs::ERXRDPT | addrs::EGPWRPT => { }
             _ => {
                 buf[1] = lo_addr;
                 data_offset = 1;
             }
         }
-        buf[1 + data_offset] = data as u8;
-        buf[2 + data_offset] = (data >> 8) as u8;
+        buf[1+data_offset] = data as u8;
+        buf[2+data_offset] = (data >> 8) as u8;
         self.rw_n(
             &mut buf,
             match lo_addr {
                 addrs::ERXRDPT => opcodes::WRXRDPT,
                 addrs::EGPWRPT => opcodes::WGPWRPT,
-                _ => opcodes::WCRU,
+                _ => opcodes::WCRU
             },
-            2 + data_offset, // extra 8-bit lo_addr before data
+            2 + data_offset     // extra 8-bit lo_addr before data
         )
     }
 
     pub fn send_opcode(&mut self, opcode: u8) -> Result<(), Error> {
         match opcode {
-            opcodes::SETETHRST | opcodes::SETPKTDEC | opcodes::SETTXRTS | opcodes::ENABLERX => {
+            opcodes::SETETHRST | opcodes::SETPKTDEC |
+            opcodes::SETTXRTS | opcodes::ENABLERX => {
                 let mut buf: [u8; 1] = [0];
                 self.rw_n(&mut buf, opcode, 0)
             }
-            _ => Err(Error::OpcodeError),
+            _ => Err(Error::OpcodeError)
         }
     }
 
@@ -191,22 +199,23 @@ impl<SPI: Transfer<u8>, NSS: OutputPin> SpiPort<SPI, NSS> {
         self.nss.set_low();
         // >=50ns min. CS_n setup time
         #[cfg(feature = "cortex-m-cpu")]
-        cortex_m::asm::delay((0.05 * (self.cpu_freq_mhz + 1.)) as u32);
+        cortex_m::asm::delay((0.05*(self.cpu_freq_mhz+1.)) as u32);
         // Start writing to SLAVE
         buf[0] = opcode;
-        let result = self.spi.transfer(&mut buf[..data_length + 1]);
+        let result = self.spi.transfer(&mut buf[..data_length+1]);
         match opcode {
-            opcodes::RCRU | opcodes::WCRU | opcodes::RRXDATA | opcodes::WGPDATA => {
+            opcodes::RCRU | opcodes::WCRU |
+            opcodes::RRXDATA | opcodes::WGPDATA => {
                 // Disable chip select
                 // >=50ns min. CS_n hold time
                 #[cfg(feature = "cortex-m-cpu")]
-                cortex_m::asm::delay((0.05 * (self.cpu_freq_mhz + 1.)) as u32);
+                cortex_m::asm::delay((0.05*(self.cpu_freq_mhz+1.)) as u32);
                 self.nss.set_high();
                 // >=20ns min. CS_n disable time
                 #[cfg(feature = "cortex-m-cpu")]
-                cortex_m::asm::delay((0.02 * (self.cpu_freq_mhz + 1.)) as u32);
+                cortex_m::asm::delay((0.02*(self.cpu_freq_mhz+1.)) as u32);    
             }
-            _ => {}
+            _ => { }
         }
         match result {
             Ok(_) => Ok(()),

src/tx.rs

@@ -6,7 +6,7 @@ pub struct TxBuffer {
     start_addr: u16,
     // The following two fields are controlled by firmware
     next_addr: u16,
-    tail_addr: u16,
+    tail_addr: u16
 }
 
 impl TxBuffer {
@@ -14,28 +14,28 @@ impl TxBuffer {
         TxBuffer {
             start_addr: 0x0000,
             next_addr: 0x0001,
-            tail_addr: 0x0000,
+            tail_addr: 0x0000
         }
     }
 
     pub fn set_start_addr(&mut self, addr: u16) {
         self.start_addr = addr;
     }
-    pub fn get_start_addr(&self) -> u16 {
+    pub fn get_start_addr(& self) -> u16{
         self.start_addr
     }
 
     pub fn set_next_addr(&mut self, addr: u16) {
         self.next_addr = addr;
     }
-    pub fn get_next_addr(&self) -> u16 {
+    pub fn get_next_addr(& self) -> u16 {
         self.next_addr
     }
 
     pub fn set_tail_addr(&mut self, addr: u16) {
         self.tail_addr = addr;
     }
-    pub fn get_tail_addr(&self) -> u16 {
+    pub fn get_tail_addr(& self) -> u16{
         self.tail_addr
     }
 }
@@ -44,14 +44,14 @@ impl TxBuffer {
 /// TODO: Generalise MAC addresses
 pub struct TxPacket {
     frame: [u8; RAW_FRAME_LENGTH_MAX],
-    frame_length: usize,
+    frame_length: usize
 }
 
 impl TxPacket {
     pub fn new() -> Self {
         TxPacket {
             frame: [0; RAW_FRAME_LENGTH_MAX],
-            frame_length: 0,
+            frame_length: 0
         }
     }