pounder_test/src/main.rs

#![no_std]
#![no_main]
#![feature(asm)]
// Enable returning `!`
#![feature(never_type)]

#[cfg(not(feature = "semihosting"))]
extern crate panic_abort;
#[cfg(feature = "semihosting")]
extern crate panic_semihosting;

#[macro_use]
extern crate log;

use core::ptr;
use core::sync::atomic::{AtomicU32, AtomicBool, Ordering};
use core::fmt::Write;
use cortex_m_rt::{exception};
use stm32h7::stm32h7x3::{self as stm32, interrupt};
use heapless::{String, Vec, consts::*};

use smoltcp as net;

use serde::{Serialize, Deserialize};
use serde_json_core::{ser::to_string, de::from_slice};

mod eth;

mod iir;
use iir::*;

#[cfg(not(feature = "semihosting"))]
fn init_log() {}

#[cfg(feature = "semihosting")]
fn init_log() {
    use log::LevelFilter;
    use cortex_m_log::log::{Logger, init as init_log};
    use cortex_m_log::printer::semihosting::{InterruptOk, hio::HStdout};
    static mut LOGGER: Option<Logger<InterruptOk<HStdout>>> = None;
    let logger = Logger {
        inner: InterruptOk::<_>::stdout().unwrap(),
        level: LevelFilter::Info,
    };
    let logger = unsafe {
        LOGGER.get_or_insert(logger)
    };

    init_log(logger).unwrap();
}

// Pull in build information (from `built` crate)
mod build_info {
    #![allow(dead_code)]
    // include!(concat!(env!("OUT_DIR"), "/built.rs"));
}

fn pwr_setup(pwr: &stm32::PWR) {
    // go to VOS1 voltage scale for high perf
    pwr.cr3.write(|w|
        w.scuen().set_bit()
         .ldoen().set_bit()
         .bypass().clear_bit()
    );
    while pwr.csr1.read().actvosrdy().bit_is_clear() {}
    pwr.d3cr.write(|w| unsafe { w.vos().bits(0b11) });  // vos1
    while pwr.d3cr.read().vosrdy().bit_is_clear() {}
}

fn rcc_reset(rcc: &stm32::RCC) {
    // Reset all peripherals
    rcc.ahb1rstr.write(|w| unsafe { w.bits(0xFFFF_FFFF) });
    rcc.ahb1rstr.write(|w| unsafe { w.bits(0)});
    rcc.apb1lrstr.write(|w| unsafe { w.bits(0xFFFF_FFFF) });
    rcc.apb1lrstr.write(|w| unsafe { w.bits(0)});
    rcc.apb1hrstr.write(|w| unsafe { w.bits(0xFFFF_FFFF) });
    rcc.apb1hrstr.write(|w| unsafe { w.bits(0)});

    rcc.ahb2rstr.write(|w| unsafe { w.bits(0xFFFF_FFFF) });
    rcc.ahb2rstr.write(|w| unsafe { w.bits(0)});
    rcc.apb2rstr.write(|w| unsafe { w.bits(0xFFFF_FFFF) });
    rcc.apb2rstr.write(|w| unsafe { w.bits(0)});

    // do not reset the cpu
    rcc.ahb3rstr.write(|w| unsafe { w.bits(0x7FFF_FFFF) });
    rcc.ahb3rstr.write(|w| unsafe { w.bits(0)});
    rcc.apb3rstr.write(|w| unsafe { w.bits(0xFFFF_FFFF) });
    rcc.apb3rstr.write(|w| unsafe { w.bits(0)});

    rcc.ahb4rstr.write(|w| unsafe { w.bits(0xFFFF_FFFF) });
    rcc.ahb4rstr.write(|w| unsafe { w.bits(0)});
    rcc.apb4rstr.write(|w| unsafe { w.bits(0xFFFF_FFFF) });
    rcc.apb4rstr.write(|w| unsafe { w.bits(0)});
}

fn rcc_pll_setup(rcc: &stm32::RCC, flash: &stm32::FLASH) {
    // Switch to HSI to mess with HSE
    rcc.cr.modify(|_, w| w.hsion().on());
    while rcc.cr.read().hsirdy().is_not_ready() {}
    rcc.cfgr.modify(|_, w| w.sw().hsi());
    while !rcc.cfgr.read().sws().is_hsi() {}
    rcc.cr.write(|w| w.hsion().on());
    rcc.cfgr.reset();

    // Ensure HSE is on and stable
    rcc.cr.modify(|_, w|
        w.hseon().on()
         .hsebyp().not_bypassed());
    while !rcc.cr.read().hserdy().is_ready() {}

    rcc.pllckselr.modify(|_, w|
        w.pllsrc().hse()
         .divm1().bits(1)  // ref prescaler
         .divm2().bits(1)  // ref prescaler
    );
    // Configure PLL1: 8MHz /1 *100 /2 = 400 MHz
    rcc.pllcfgr.modify(|_, w|
        w.pll1vcosel().wide_vco()  // 192-836 MHz VCO
         .pll1rge().range8()  // 8-16 MHz PFD
         .pll1fracen().reset()
         .divp1en().enabled()
         .pll2vcosel().medium_vco()  // 150-420 MHz VCO
         .pll2rge().range8()  // 8-16 MHz PFD
         .pll2fracen().reset()
         .divp2en().enabled()
         .divq2en().enabled()
    );
    rcc.pll1divr.write(|w| unsafe {
        w.divn1().bits(100 - 1)  // feebdack divider
         .divp1().div2()  // p output divider
    });
    rcc.cr.modify(|_, w| w.pll1on().on());
    while !rcc.cr.read().pll1rdy().is_ready() {}

    // Configure PLL2: 8MHz /1 *25 / 2 = 100 MHz
    rcc.pll2divr.write(|w| unsafe {
        w.divn1().bits(25 - 1)  // feebdack divider
         .divp1().bits(2 - 1)  // p output divider
         .divq1().bits(2 - 1)  // q output divider
    });
    rcc.cr.modify(|_, w| w.pll2on().on());
    while !rcc.cr.read().pll2rdy().is_ready() {}

    // hclk 200 MHz, pclk 100 MHz
    rcc.d1cfgr.write(|w|
        w.d1cpre().div1()  // sys_ck not divided
         .hpre().div2()  // rcc_hclk3 = sys_d1cpre_ck / 2
         .d1ppre().div2() // rcc_pclk3 = rcc_hclk3 / 2
    );
    rcc.d2cfgr.write(|w|
        w.d2ppre1().div2()  // rcc_pclk1 = rcc_hclk3 / 2
         .d2ppre2().div2() // rcc_pclk2 = rcc_hclk3 / 2
    );
    rcc.d3cfgr.write(|w|
        w.d3ppre().div2()  // rcc_pclk4 = rcc_hclk3 / 2
    );

    // 2 wait states, 0b10 programming delay
    // 185-210 MHz
    flash.acr.write(|w| unsafe {
        w.wrhighfreq().bits(2)
         .latency().bits(2)
    });
    while flash.acr.read().latency().bits() != 2 {}

    // CSI for I/O compensationc ell
    rcc.cr.modify(|_, w| w.csion().on());
    while !rcc.cr.read().csirdy().is_ready() {}

    // Set system clock to pll1_p
    rcc.cfgr.modify(|_, w| w.sw().pll1());
    while !rcc.cfgr.read().sws().is_pll1() {}

    rcc.d1ccipr.write(|w| w.ckpersel().hse());
    rcc.d2ccip1r.modify(|_, w|
        w.spi123sel().pll2_p()
         .spi45sel().pll2_q()
    );
    rcc.d3ccipr.modify(|_, w| w.spi6sel().pll2_q());
}

fn io_compensation_setup(syscfg: &stm32::SYSCFG) {
    syscfg.cccsr.modify(|_, w|
        w.en().set_bit()
         .cs().clear_bit()
         .hslv().clear_bit()
    );
    while syscfg.cccsr.read().ready().bit_is_clear() {}
}

fn gpio_setup(gpioa: &stm32::GPIOA, gpiob: &stm32::GPIOB, gpiod: &stm32::GPIOD,
              gpioe: &stm32::GPIOE, gpiof: &stm32::GPIOF, gpiog: &stm32::GPIOG) {
    // FP_LED0
    gpiod.otyper.modify(|_, w| w.ot5().push_pull());
    gpiod.moder.modify(|_, w| w.moder5().output());
    gpiod.odr.modify(|_, w| w.odr5().clear_bit());

    // FP_LED1
    gpiod.otyper.modify(|_, w| w.ot6().push_pull());
    gpiod.moder.modify(|_, w| w.moder6().output());
    gpiod.odr.modify(|_, w| w.odr6().clear_bit());

    // LED_FP2
    gpiog.otyper.modify(|_, w| w.ot4().push_pull());
    gpiog.moder.modify(|_, w| w.moder4().output());
    gpiog.odr.modify(|_, w| w.odr4().clear_bit());

    // LED_FP3
    gpiod.otyper.modify(|_, w| w.ot12().push_pull());
    gpiod.moder.modify(|_, w| w.moder12().output());
    gpiod.odr.modify(|_, w| w.odr12().clear_bit());

    // AFE0_A0,1: PG2,PG3
    gpiog.otyper.modify(|_, w|
        w.ot2().push_pull()
         .ot3().push_pull()
    );
    gpiog.moder.modify(|_, w|
        w.moder2().output()
         .moder3().output()
    );
    gpiog.odr.modify(|_, w|
        w.odr2().clear_bit()
         .odr3().clear_bit()
    );

    // ADC0
    // SCK: PG11
    gpiog.moder.modify(|_, w| w.moder11().alternate());
    gpiog.otyper.modify(|_, w| w.ot11().push_pull());
    gpiog.ospeedr.modify(|_, w| w.ospeedr11().very_high_speed());
    gpiog.afrh.modify(|_, w| w.afr11().af5());
    // MOSI: PD7
    // MISO: PA6
    gpioa.moder.modify(|_, w| w.moder6().alternate());
    gpioa.afrl.modify(|_, w| w.afr6().af5());
    // NSS: PG10
    gpiog.moder.modify(|_, w| w.moder10().alternate());
    gpiog.otyper.modify(|_, w| w.ot10().push_pull());
    gpiog.ospeedr.modify(|_, w| w.ospeedr10().very_high_speed());
    gpiog.afrh.modify(|_, w| w.afr10().af5());

    // DAC0
    // SCK: PB10
    gpiob.moder.modify(|_, w| w.moder10().alternate());
    gpiob.otyper.modify(|_, w| w.ot10().push_pull());
    gpiob.ospeedr.modify(|_, w| w.ospeedr10().very_high_speed());
    gpiob.afrh.modify(|_, w| w.afr10().af5());
    // MOSI: PB15
    gpiob.moder.modify(|_, w| w.moder15().alternate());
    gpiob.otyper.modify(|_, w| w.ot15().push_pull());
    gpiob.ospeedr.modify(|_, w| w.ospeedr15().very_high_speed());
    gpiob.afrh.modify(|_, w| w.afr15().af5());
    // MISO: PB14
    // NSS: PB9
    gpiob.moder.modify(|_, w| w.moder9().alternate());
    gpiob.otyper.modify(|_, w| w.ot9().push_pull());
    gpiob.ospeedr.modify(|_, w| w.ospeedr9().very_high_speed());
    gpiob.afrh.modify(|_, w| w.afr9().af5());

    // DAC0_LDAC: PE11
    gpioe.moder.modify(|_, w| w.moder11().output());
    gpioe.otyper.modify(|_, w| w.ot11().push_pull());
    gpioe.odr.modify(|_, w| w.odr11().clear_bit());

    // DAC_CLR: PE12
    gpioe.moder.modify(|_, w| w.moder12().output());
    gpioe.otyper.modify(|_, w| w.ot12().push_pull());
    gpioe.odr.modify(|_, w| w.odr12().set_bit());

    // AFE1_A0,1: PD14,PD15
    gpiod.otyper.modify(|_, w|
        w.ot14().push_pull()
         .ot15().push_pull()
    );
    gpiod.moder.modify(|_, w|
        w.moder14().output()
         .moder15().output()
    );
    gpiod.odr.modify(|_, w|
        w.odr14().clear_bit()
         .odr15().clear_bit()
    );

    // ADC1
    // SCK: PF6
    gpiof.moder.modify(|_, w| w.moder7().alternate());
    gpiof.otyper.modify(|_, w| w.ot7().push_pull());
    gpiof.ospeedr.modify(|_, w| w.ospeedr7().very_high_speed());
    gpiof.afrl.modify(|_, w| w.afr7().af5());
    // MOSI: PF9
    // MISO: PF7
    gpiof.moder.modify(|_, w| w.moder8().alternate());
    gpiof.afrh.modify(|_, w| w.afr8().af5());
    // NSS: PF8
    gpiof.moder.modify(|_, w| w.moder6().alternate());
    gpiof.otyper.modify(|_, w| w.ot6().push_pull());
    gpiof.ospeedr.modify(|_, w| w.ospeedr6().very_high_speed());
    gpiof.afrl.modify(|_, w| w.afr6().af5());

    // DAC1
    // SCK: PE2
    gpioe.moder.modify(|_, w| w.moder2().alternate());
    gpioe.otyper.modify(|_, w| w.ot2().push_pull());
    gpioe.ospeedr.modify(|_, w| w.ospeedr2().very_high_speed());
    gpioe.afrl.modify(|_, w| w.afr2().af5());
    // MOSI: PE6
    gpioe.moder.modify(|_, w| w.moder6().alternate());
    gpioe.otyper.modify(|_, w| w.ot6().push_pull());
    gpioe.ospeedr.modify(|_, w| w.ospeedr6().very_high_speed());
    gpioe.afrl.modify(|_, w| w.afr6().af5());
    // MISO: PE5
    // NSS: PE4
    gpioe.moder.modify(|_, w| w.moder4().alternate());
    gpioe.otyper.modify(|_, w| w.ot4().push_pull());
    gpioe.ospeedr.modify(|_, w| w.ospeedr4().very_high_speed());
    gpioe.afrl.modify(|_, w| w.afr4().af5());

    // DAC1_LDAC: PE15
    gpioe.moder.modify(|_, w| w.moder15().output());
    gpioe.otyper.modify(|_, w| w.ot15().push_pull());
    gpioe.odr.modify(|_, w| w.odr15().clear_bit());
}

// ADC0
fn spi1_setup(spi1: &stm32::SPI1) {
    spi1.cfg1.modify(|_, w|
        w.mbr().div4()
         .dsize().bits(16 - 1)
         .fthlv().one_frame()
    );
    spi1.cfg2.modify(|_, w|
        w.afcntr().controlled()
         .ssom().not_asserted()
         .ssoe().enabled()
         .ssiop().active_low()
         .ssm().disabled()
         .cpol().idle_high()
         .cpha().second_edge()
         .lsbfrst().msbfirst()
         .master().master()
         .sp().motorola()
         .comm().receiver()
         .ioswp().disabled()
         .midi().bits(0)
         .mssi().bits(6)
    );
    spi1.cr2.modify(|_, w| w.tsize().bits(1));
    spi1.cr1.write(|w| w.spe().set_bit());
}

// ADC1
fn spi5_setup(spi5: &stm32::SPI5) {
    spi5.cfg1.modify(|_, w|
        w.mbr().div4()
         .dsize().bits(16 - 1)
         .fthlv().one_frame()
    );
    spi5.cfg2.modify(|_, w|
        w.afcntr().controlled()
         .ssom().not_asserted()
         .ssoe().enabled()
         .ssiop().active_low()
         .ssm().disabled()
         .cpol().idle_high()
         .cpha().second_edge()
         .lsbfrst().msbfirst()
         .master().master()
         .sp().motorola()
         .comm().receiver()
         .ioswp().disabled()
         .midi().bits(0)
         .mssi().bits(6)
    );
    spi5.cr2.modify(|_, w| w.tsize().bits(1));
    spi5.cr1.write(|w| w.spe().set_bit());
}

// DAC0
fn spi2_setup(spi2: &stm32::SPI2) {
    spi2.cfg1.modify(|_, w|
        w.mbr().div2()
         .dsize().bits(16 - 1)
         .fthlv().one_frame()
    );
    spi2.cfg2.modify(|_, w|
        w.afcntr().controlled()
         .ssom().not_asserted()
         .ssoe().enabled()
         .ssiop().active_low()
         .ssm().disabled()
         .cpol().idle_low()
         .cpha().first_edge()
         .lsbfrst().msbfirst()
         .master().master()
         .sp().motorola()
         .comm().transmitter()
         .ioswp().disabled()
         .midi().bits(0)
         .mssi().bits(0)
    );
    spi2.cr2.modify(|_, w| w.tsize().bits(0));
    spi2.cr1.write(|w| w.spe().enabled());
    spi2.cr1.modify(|_, w| w.cstart().started());
}

// DAC1
fn spi4_setup(spi4: &stm32::SPI4) {
    spi4.cfg1.modify(|_, w|
        w.mbr().div2()
         .dsize().bits(16 - 1)
         .fthlv().one_frame()
    );
    spi4.cfg2.modify(|_, w|
        w.afcntr().controlled()
         .ssom().not_asserted()
         .ssoe().enabled()
         .ssiop().active_low()
         .ssm().disabled()
         .cpol().idle_low()
         .cpha().first_edge()
         .lsbfrst().msbfirst()
         .master().master()
         .sp().motorola()
         .comm().transmitter()
         .ioswp().disabled()
         .midi().bits(0)
         .mssi().bits(0)
    );
    spi4.cr2.modify(|_, w| w.tsize().bits(0));
    spi4.cr1.write(|w| w.spe().enabled());
    spi4.cr1.modify(|_, w| w.cstart().started());
}

fn tim2_setup(tim2: &stm32::TIM2) {
    tim2.psc.write(|w| unsafe { w.psc().bits(200 - 1) });  // from 200 MHz
    tim2.arr.write(|w| unsafe { w.bits(2 - 1) });  // µs
    tim2.dier.write(|w| w.ude().set_bit());
    tim2.egr.write(|w| w.ug().set_bit());
    tim2.cr1.modify(|_, w|
        w.dir().clear_bit()  // up
         .cen().set_bit());  // enable
}

fn dma1_setup(dma1: &stm32::DMA1, dmamux1: &stm32::DMAMUX1, ma: usize, pa0: usize, pa1: usize) {
    dma1.st[0].cr.modify(|_, w| w.en().clear_bit());
    while dma1.st[0].cr.read().en().bit_is_set() {}

    dma1.st[0].par.write(|w| unsafe { w.bits(pa0 as u32) });
    dma1.st[0].m0ar.write(|w| unsafe { w.bits(ma as u32) });
    dma1.st[0].ndtr.write(|w| unsafe { w.ndt().bits(1) });
    dmamux1.ccr[0].modify(|_, w| w.dmareq_id().tim2_up());
    dma1.st[0].cr.modify(|_, w| unsafe {
        w.pl().bits(0b01)  // medium
         .circ().set_bit()  // reload ndtr
         .msize().bits(0b10)  // 32
         .minc().clear_bit()
         .mburst().bits(0b00)
         .psize().bits(0b10)  // 32
         .pinc().clear_bit()
         .pburst().bits(0b00)
         .dbm().clear_bit()
         .dir().bits(0b01)  // memory_to_peripheral
         .pfctrl().clear_bit()  // dma is FC
    });
    dma1.st[0].fcr.modify(|_, w| w.dmdis().clear_bit());
    dma1.st[0].cr.modify(|_, w| w.en().set_bit());

    dma1.st[1].cr.modify(|_, w| w.en().clear_bit());
    while dma1.st[1].cr.read().en().bit_is_set() {}

    dma1.st[1].par.write(|w| unsafe { w.bits(pa1 as u32) });
    dma1.st[1].m0ar.write(|w| unsafe { w.bits(ma as u32) });
    dma1.st[1].ndtr.write(|w| unsafe { w.ndt().bits(1) });
    dmamux1.ccr[1].modify(|_, w| w.dmareq_id().tim2_up());
    dma1.st[1].cr.modify(|_, w| unsafe {
        w.pl().bits(0b01)  // medium
         .circ().set_bit()  // reload ndtr
         .msize().bits(0b10)  // 32
         .minc().clear_bit()
         .mburst().bits(0b00)
         .psize().bits(0b10)  // 32
         .pinc().clear_bit()
         .pburst().bits(0b00)
         .dbm().clear_bit()
         .dir().bits(0b01)  // memory_to_peripheral
         .pfctrl().clear_bit()  // dma is FC
    });
    dma1.st[1].fcr.modify(|_, w| w.dmdis().clear_bit());
    dma1.st[1].cr.modify(|_, w| w.en().set_bit());
}

const SCALE: f32 = ((1 << 15) - 1) as f32;

#[link_section = ".sram1.datspi"]
static mut DAT: u32 = 0x201;  // EN | CSTART

static ETHERNET_PENDING: AtomicBool = AtomicBool::new(true);

const TCP_RX_BUFFER_SIZE: usize = 8192;
const TCP_TX_BUFFER_SIZE: usize = 8192;

macro_rules! create_socket {
    ($set:ident, $rx_storage:ident, $tx_storage:ident, $target:ident) => (
        let mut $rx_storage = [0; TCP_RX_BUFFER_SIZE];
        let mut $tx_storage = [0; TCP_TX_BUFFER_SIZE];
        let tcp_rx_buffer = net::socket::TcpSocketBuffer::new(&mut $rx_storage[..]);
        let tcp_tx_buffer = net::socket::TcpSocketBuffer::new(&mut $tx_storage[..]);
        let tcp_socket = net::socket::TcpSocket::new(tcp_rx_buffer, tcp_tx_buffer);
        let $target = $set.add(tcp_socket);
    )
}

#[rtfm::app(device = stm32h7::stm32h7x3)]
const APP: () = {
    static SPI: (stm32::SPI1, stm32::SPI2, stm32::SPI4, stm32::SPI5) = ();

    static mut IIR_STATE: [IIRState; 2] = [[0.; 5]; 2];
    static mut IIR_CH: [IIR; 2] = [
        IIR {
            ba: [0., 0., 0., 0., 0.],
            y_offset: 0.,
            y_min: -SCALE - 1.,
            y_max: SCALE
        };
    2];
    static ETHERNET_PERIPH: (stm32::ETHERNET_MAC, stm32::ETHERNET_DMA, stm32::ETHERNET_MTL) = ();

    #[link_section = ".sram3.eth"]
    static mut ETHERNET: eth::Device = eth::Device::new();

    #[init(schedule = [tick])]
    fn init(c: init::Context) -> init::LateResources {
        let dp = c.device;
        let cp = c.core;

        let rcc = dp.RCC;
        rcc_reset(&rcc);

        init_log();
        // info!("Version {} {}", build_info::PKG_VERSION, build_info::GIT_VERSION.unwrap());
        // info!("Built on {}", build_info::BUILT_TIME_UTC);
        // info!("{} {}", build_info::RUSTC_VERSION, build_info::TARGET);

        pwr_setup(&dp.PWR);
        rcc_pll_setup(&rcc, &dp.FLASH);
        rcc.apb4enr.modify(|_, w| w.syscfgen().set_bit());
        io_compensation_setup(&dp.SYSCFG);

        cp.SCB.enable_icache();
        // TODO: ETH DMA coherence issues
        // cp.SCB.enable_dcache(&mut cp.CPUID);
        // cp.DWT.enable_cycle_counter();

        rcc.ahb4enr.modify(|_, w|
            w.gpioaen().set_bit()
            .gpioben().set_bit()
            .gpiocen().set_bit()
            .gpioden().set_bit()
            .gpioeen().set_bit()
            .gpiofen().set_bit()
            .gpiogen().set_bit()
        );
        gpio_setup(&dp.GPIOA, &dp.GPIOB, &dp.GPIOD, &dp.GPIOE, &dp.GPIOF, &dp.GPIOG);

        rcc.apb1lenr.modify(|_, w| w.spi2en().set_bit());
        let spi2 = dp.SPI2;
        spi2_setup(&spi2);

        rcc.apb2enr.modify(|_, w| w.spi4en().set_bit());
        let spi4 = dp.SPI4;
        spi4_setup(&spi4);

        rcc.apb2enr.modify(|_, w| w.spi1en().set_bit());
        let spi1 = dp.SPI1;
        spi1_setup(&spi1);
        spi1.ier.write(|w| w.eotie().set_bit());

        rcc.apb2enr.modify(|_, w| w.spi5en().set_bit());
        let spi5 = dp.SPI5;
        spi5_setup(&spi5);
        // spi5.ier.write(|w| w.eotie().set_bit());

        rcc.ahb2enr.modify(|_, w|
            w
                .sram1en().set_bit()
                .sram2en().set_bit()
                .sram3en().set_bit()
        );
        rcc.ahb1enr.modify(|_, w| w.dma1en().set_bit());
        // init SRAM1 rodata can't load with sram1 disabled
        unsafe { DAT = 0x201 };  // EN | CSTART
        cortex_m::asm::dsb();
        let dat_addr = unsafe { &DAT as *const _ } as usize;
        cp.SCB.clean_dcache_by_address(dat_addr, 4);

        dma1_setup(&dp.DMA1, &dp.DMAMUX1, dat_addr,
                &spi1.cr1 as *const _ as usize,
                &spi5.cr1 as *const _ as usize);

        rcc.apb1lenr.modify(|_, w| w.tim2en().set_bit());

        // work around the SPI stall erratum
        let dbgmcu = dp.DBGMCU;
        dbgmcu.apb1lfz1.modify(|_, w| w.tim2().set_bit());

        tim2_setup(&dp.TIM2);

        eth::setup(&rcc, &dp.SYSCFG);
        eth::setup_pins(&dp.GPIOA, &dp.GPIOB, &dp.GPIOC, &dp.GPIOG);

        c.schedule.tick(rtfm::Instant::now()).unwrap();

        init::LateResources {
            SPI: (spi1, spi2, spi4, spi5),
            ETHERNET_PERIPH: (dp.ETHERNET_MAC, dp.ETHERNET_DMA, dp.ETHERNET_MTL),
        }
    }

    #[idle(resources = [ETHERNET, ETHERNET_PERIPH])]
    fn idle(c: idle::Context) -> ! {
        let (MAC, DMA, MTL) = c.resources.ETHERNET_PERIPH;

        let hardware_addr = net::wire::EthernetAddress([0x10, 0xE2, 0xD5, 0x00, 0x03, 0x00]);
        unsafe { c.resources.ETHERNET.init(hardware_addr, MAC, DMA, MTL) };
        let mut neighbor_cache_storage = [None; 8];
        let neighbor_cache = net::iface::NeighborCache::new(&mut neighbor_cache_storage[..]);
        let local_addr = net::wire::IpAddress::v4(10, 0, 16, 99);
        let mut ip_addrs = [net::wire::IpCidr::new(local_addr, 24)];
        let mut iface = net::iface::EthernetInterfaceBuilder::new(c.resources.ETHERNET)
                    .ethernet_addr(hardware_addr)
                    .neighbor_cache(neighbor_cache)
                    .ip_addrs(&mut ip_addrs[..])
                    .finalize();
        let mut socket_set_entries: [_; 8] = Default::default();
        let mut sockets = net::socket::SocketSet::new(&mut socket_set_entries[..]);
        create_socket!(sockets, tcp_rx_storage0, tcp_tx_storage0, tcp_handle0);
        create_socket!(sockets, tcp_rx_storage0, tcp_tx_storage0, tcp_handle1);

        // unsafe { eth::enable_interrupt(DMA); }
        let mut last = 0u32;
        let mut last_iter = rtfm::Instant::now();
        //let mut server = Server::new();
        loop {
            // if ETHERNET_PENDING.swap(false, Ordering::Relaxed) { }
            let mut time = last;
            if rtfm::Instant::now() >= last_iter + 200_000.cycles() {
                last_iter += 200_000.cycles();
                time += 1;
            }
            {
                let socket = &mut *sockets.get::<net::socket::TcpSocket>(tcp_handle0);
                if !(socket.is_open() || socket.is_listening()) {
                    socket.listen(1234).unwrap_or_else(|e| warn!("TCP listen error: {:?}", e));
                } else if time > last && socket.can_send() {
                    last = time;
                    //handle_status(socket, time);
                }
            }
            {
                let socket = &mut *sockets.get::<net::socket::TcpSocket>(tcp_handle1);
                if !(socket.is_open() || socket.is_listening()) {
                    socket.listen(1235).unwrap_or_else(|e| warn!("TCP listen error: {:?}", e));
                } else {
                    //server.handle_command(socket);
                }
            }

            if !match iface.poll(&mut sockets, net::time::Instant::from_millis(time as i64)) {
                Ok(changed) => changed,
                Err(net::Error::Unrecognized) => true,
                Err(e) => { info!("iface poll error: {:?}", e); true }
            } {
                // cortex_m::asm::wfi();
            }
        }
    }

    #[task(schedule = [tick])]
    fn tick(c: tick::Context) {
        static mut TIME: u32 = 0;
        *TIME += 1;
        const PERIOD: u32 = 200_000_000;
        c.schedule.tick(c.scheduled + PERIOD.cycles()).unwrap();
    }

    // seems to slow it down
    // #[link_section = ".data.spi1"]
    #[interrupt(resources = [SPI, IIR_STATE, IIR_CH], priority = 3)]
    fn SPI1(c: SPI1::Context) {
        #[cfg(feature = "bkpt")]
        cortex_m::asm::bkpt();
        let (spi1, spi2, spi4, spi5) = c.resources.SPI;
        let iir_ch = c.resources.IIR_CH;
        let iir_state = c.resources.IIR_STATE;

        let sr = spi1.sr.read();
        if sr.eot().bit_is_set() {
            spi1.ifcr.write(|w| w.eotc().set_bit());
        }
        if sr.rxp().bit_is_set() {
            let rxdr = &spi1.rxdr as *const _ as *const u16;
            let a = unsafe { ptr::read_volatile(rxdr) };
            let x0 = f32::from(a as i16);
            let y0 = iir_ch[0].update(&mut iir_state[0], x0);
            let d = y0 as i16 as u16 ^ 0x8000;
            let txdr = &spi2.txdr as *const _ as *mut u16;
            unsafe { ptr::write_volatile(txdr, d) };
        }

        let sr = spi5.sr.read();
        if sr.eot().bit_is_set() {
            spi5.ifcr.write(|w| w.eotc().set_bit());
        }
        if sr.rxp().bit_is_set() {
            let rxdr = &spi5.rxdr as *const _ as *const u16;
            let a = unsafe { ptr::read_volatile(rxdr) };
            let x0 = f32::from(a as i16);
            let y0 = iir_ch[1].update(&mut iir_state[1], x0);
            let d = y0 as i16 as u16 ^ 0x8000;
            let txdr = &spi4.txdr as *const _ as *mut u16;
            unsafe { ptr::write_volatile(txdr, d) };
        }
        #[cfg(feature = "bkpt")]
        cortex_m::asm::bkpt();
    }

    /*
    #[interrupt(resources = [ETHERNET_PERIPH], priority = 1)]
    fn ETH(c: ETH::Context) {
        let dma = &c.resources.ETHERNET_PERIPH.1;
        ETHERNET_PENDING.store(true, Ordering::Relaxed);
        unsafe { eth::interrupt_handler(dma) }
    }
    */

    extern "C" {
        // hw interrupt handlers for RTFM to use for scheduling tasks
        // one per priority
        fn DCMI();
        fn JPEG();
        fn SDMMC();
    }
};

#[derive(Deserialize,Serialize)]
struct Request {
    channel: u8,
    iir: IIR,
}

#[derive(Serialize)]
struct Response<'a> {
    code: i32,
    message: &'a str,
}

#[derive(Serialize)]
struct Status {
    t: u32,
    x0: f32,
    y0: f32,
    x1: f32,
    y1: f32
}

struct Server {
    data: Vec<u8, U256>,
    discard: bool,
}

fn reply<T: Serialize>(socket: &mut net::socket::TcpSocket, msg: &T) {
    let mut u: String<U128> = to_string(msg).unwrap();
    u.push('\n').unwrap();
    socket.write_str(&u).unwrap();
}

impl Server {
    fn new() -> Self {
        Self { data: Vec::new(), discard: false }
    }

    fn handle_command(&mut self, socket: &mut net::socket::TcpSocket) {
        while socket.can_recv() {
            let found = socket.recv(|buf| {
                let (len, found) = match buf.iter().position(|&c| c as char == '\n') {
                    Some(end) => (end + 1, true),
                    None => (buf.len(), false),
                };
                if self.data.len() + len >= self.data.capacity() {
                    self.discard = true;
                    self.data.clear();
                } else if !self.discard && len > 0 {
                    self.data.extend_from_slice(&buf[..len - 1]).unwrap();
                }
                (len, found)
            }).unwrap();
            if !found {
                continue;
            }
            let resp = if self.discard {
                self.discard = false;
                Response{ code: 520, message: "command buffer overflow" }
            } else {
                match from_slice::<Request>(&self.data) {
                    Ok(request) => {
                        if request.channel > 1 {
                            Response{ code: 530, message: "invalid channel" }
                        } else {
                            //unsafe { IIR_CH[request.channel as usize] = request.iir; };
                            Response{ code: 200, message: "ok" }
                        }
                    },
                    Err(err) => {
                        warn!("parse error {:?}", err);
                        Response{ code: 550, message: "parse error" }
                    },
                }
            };
            self.data.clear();
            reply(socket, &resp);
            socket.close();
        }
    }
}

fn handle_status(socket: &mut net::socket::TcpSocket, time: u32,
                 iir_state: &[IIRState]) {
    let s = unsafe { Status{
        t: time,
        x0: iir_state[0][0],
        y0: iir_state[0][2],
        x1: iir_state[1][0],
        y1: iir_state[1][2],
    }};
    reply(socket, &s);
}

#[exception]
fn HardFault(ef: &cortex_m_rt::ExceptionFrame) -> ! {
    panic!("HardFault at {:#?}", ef);
}

#[exception]
fn DefaultHandler(irqn: i16) {
    panic!("Unhandled exception (IRQn = {})", irqn);
}