main.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013-2020 Damien P. George
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <stdio.h>
#include <string.h>

#include "py/runtime.h"
#include "py/stackctrl.h"
#include "py/gc.h"
#include "py/mperrno.h"
#include "py/mphal.h"
#include "shared/readline/readline.h"
#include "shared/runtime/pyexec.h"
#include "shared/runtime/softtimer.h"
#include "lib/oofatfs/ff.h"
#include "lib/littlefs/lfs1.h"
#include "lib/littlefs/lfs1_util.h"
#include "lib/littlefs/lfs2.h"
#include "lib/littlefs/lfs2_util.h"
#include "extmod/modmachine.h"
#include "extmod/modnetwork.h"
#include "extmod/vfs.h"
#include "extmod/vfs_fat.h"
#include "extmod/vfs_lfs.h"

#if MICROPY_PY_LWIP
#include "lwip/init.h"
#include "lwip/apps/mdns.h"
#if MICROPY_PY_NETWORK_CYW43
#include "lib/cyw43-driver/src/cyw43.h"
#endif
#endif

#if MICROPY_PY_BLUETOOTH
#include "extmod/modbluetooth.h"
#endif

#include "boardctrl.h"
#include "mpbthciport.h"
#include "mpu.h"
#include "rfcore.h"
#include "systick.h"
#include "pendsv.h"
#include "powerctrl.h"
#include "pybthread.h"
#include "gccollect.h"
#include "factoryreset.h"
#include "modmachine.h"
#include "i2c.h"
#include "spi.h"
#include "uart.h"
#include "timer.h"
#include "led.h"
#include "pin.h"
#include "extint.h"
#include "usrsw.h"
#include "usb.h"
#include "rtc.h"
#include "storage.h"
#include "sdcard.h"
#include "sdram.h"
#include "rng.h"
#include "accel.h"
#include "servo.h"
#include "dac.h"
#include "pyb_can.h"
#include "subghz.h"

#if MICROPY_PY_THREAD
static pyb_thread_t pyb_thread_main;
#endif

#if defined(MICROPY_HW_UART_REPL)
#ifndef MICROPY_HW_UART_REPL_RXBUF
#define MICROPY_HW_UART_REPL_RXBUF (260)
#endif
static machine_uart_obj_t pyb_uart_repl_obj;
static uint8_t pyb_uart_repl_rxbuf[MICROPY_HW_UART_REPL_RXBUF];
#endif

void nlr_jump_fail(void *val) {
    printf("FATAL: uncaught exception %p\n", val);
    mp_obj_print_exception(&mp_plat_print, MP_OBJ_FROM_PTR(val));
    MICROPY_BOARD_FATAL_ERROR("");
}

void abort(void) {
    MICROPY_BOARD_FATAL_ERROR("abort");
}

#ifndef NDEBUG
void MP_WEAK __assert_func(const char *file, int line, const char *func, const char *expr) {
    (void)func;
    printf("Assertion '%s' failed, at file %s:%d\n", expr, file, line);
    MICROPY_BOARD_FATAL_ERROR("");
}
#endif

static mp_obj_t pyb_main(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_opt, MP_ARG_INT, {.u_int = 0} }
    };

    if (mp_obj_is_str(pos_args[0])) {
        MP_STATE_PORT(pyb_config_main) = pos_args[0];

        // parse args
        mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
        mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
        #if MICROPY_ENABLE_COMPILER
        MP_STATE_VM(mp_optimise_value) = args[0].u_int;
        #endif
    }
    return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_KW(pyb_main_obj, 1, pyb_main);

#if MICROPY_HW_FLASH_MOUNT_AT_BOOT
// avoid inlining to avoid stack usage within main()
MP_NOINLINE static bool init_flash_fs(uint reset_mode) {
    if (reset_mode == BOARDCTRL_RESET_MODE_FACTORY_FILESYSTEM) {
        // Asked by user to reset filesystem
        factory_reset_create_filesystem();
    }

    // Default block device to entire flash storage
    mp_obj_t bdev = MP_OBJ_FROM_PTR(&pyb_flash_obj);

    int ret;

    #if MICROPY_VFS_LFS1 || MICROPY_VFS_LFS2

    // Try to detect the block device used for the main filesystem based on the
    // contents of the superblock, which can be the first or second block.
    mp_int_t len = -1;
    uint8_t buf[64];
    for (size_t block_num = 0; block_num <= 1; ++block_num) {
        ret = storage_readblocks_ext(buf, block_num, 0, sizeof(buf));

        #if MICROPY_VFS_LFS1
        if (ret == 0 && memcmp(&buf[40], "littlefs", 8) == 0) {
            // LFS1
            lfs1_superblock_t *superblock = (void *)&buf[12];
            uint32_t block_size = lfs1_fromle32(superblock->d.block_size);
            uint32_t block_count = lfs1_fromle32(superblock->d.block_count);
            len = block_count * block_size;
            break;
        }
        #endif

        #if MICROPY_VFS_LFS2
        if (ret == 0 && memcmp(&buf[8], "littlefs", 8) == 0) {
            // LFS2
            lfs2_superblock_t *superblock = (void *)&buf[20];
            uint32_t block_size = lfs2_fromle32(superblock->block_size);
            uint32_t block_count = lfs2_fromle32(superblock->block_count);
            len = block_count * block_size;
            break;
        }
        #endif
    }

    if (len != -1) {
        // Detected a littlefs filesystem so create correct block device for it
        mp_obj_t lfs_bdev = pyb_flash_new_obj(0, len);
        if (lfs_bdev == mp_const_none) {
            // Invalid len detected, filesystem header block likely corrupted.
            // Create bdev with default size to attempt to mount the whole flash or
            // let user attempt recovery if desired.
            bdev = pyb_flash_new_obj(0, -1);
        } else {
            bdev = lfs_bdev;
        }
    }

    #endif

    // Try to mount the flash on "/flash" and chdir to it for the boot-up directory.
    mp_obj_t mount_point = MP_OBJ_NEW_QSTR(MP_QSTR__slash_flash);
    ret = mp_vfs_mount_and_chdir_protected(bdev, mount_point);

    if (ret == -MP_ENODEV && bdev == MP_OBJ_FROM_PTR(&pyb_flash_obj)
        && reset_mode != BOARDCTRL_RESET_MODE_FACTORY_FILESYSTEM) {
        // No filesystem, bdev is still the default (so didn't detect a possibly corrupt littlefs),
        // and didn't already create a filesystem, so try to create a fresh one now.
        ret = factory_reset_create_filesystem();
        if (ret == 0) {
            ret = mp_vfs_mount_and_chdir_protected(bdev, mount_point);
        }
    }

    if (ret != 0) {
        mp_printf(&mp_plat_print, "MPY: can't mount flash\n");
        return false;
    }

    return true;
}
#endif

#if MICROPY_HW_SDCARD_MOUNT_AT_BOOT
static bool init_sdcard_fs(void) {
    bool first_part = true;
    for (int part_num = 1; part_num <= 5; ++part_num) {
        // create vfs object
        fs_user_mount_t *vfs_fat = m_new_obj_maybe(fs_user_mount_t);
        mp_vfs_mount_t *vfs = m_new_obj_maybe(mp_vfs_mount_t);
        if (vfs == NULL || vfs_fat == NULL) {
            break;
        }
        vfs_fat->blockdev.flags = MP_BLOCKDEV_FLAG_FREE_OBJ;
        if (part_num == 5) {
            if (!first_part) {
                break;
            }
            // partitions 1-4 couldn't be mounted, so try FATFS auto-detect mode
            // which will work if there is no partition table, just a filesystem
            sdcard_init_vfs(vfs_fat, 0);
        } else {
            sdcard_init_vfs(vfs_fat, part_num);
        }

        // try to mount the partition
        FRESULT res = f_mount(&vfs_fat->fatfs);

        if (res != FR_OK) {
            // couldn't mount
            m_del_obj(fs_user_mount_t, vfs_fat);
            m_del_obj(mp_vfs_mount_t, vfs);
        } else {
            // mounted via FatFs, now mount the SD partition in the VFS
            if (first_part) {
                // the first available partition is traditionally called "sd" for simplicity
                vfs->str = "/sd";
                vfs->len = 3;
            } else {
                // subsequent partitions are numbered by their index in the partition table
                if (part_num == 2) {
                    vfs->str = "/sd2";
                } else if (part_num == 3) {
                    vfs->str = "/sd3";
                } else {
                    vfs->str = "/sd4";
                }
                vfs->len = 4;
            }
            vfs->obj = MP_OBJ_FROM_PTR(vfs_fat);
            vfs->next = NULL;
            for (mp_vfs_mount_t **m = &MP_STATE_VM(vfs_mount_table);; m = &(*m)->next) {
                if (*m == NULL) {
                    *m = vfs;
                    break;
                }
            }

            #if MICROPY_HW_ENABLE_USB
            if (pyb_usb_storage_medium == PYB_USB_STORAGE_MEDIUM_NONE) {
                // if no USB MSC medium is selected then use the SD card
                pyb_usb_storage_medium = PYB_USB_STORAGE_MEDIUM_SDCARD;
            }
            #endif

            #if MICROPY_HW_ENABLE_USB
            // only use SD card as current directory if that's what the USB medium is
            if (pyb_usb_storage_medium == PYB_USB_STORAGE_MEDIUM_SDCARD)
            #endif
            {
                if (first_part) {
                    // use SD card as current directory
                    MP_STATE_PORT(vfs_cur) = vfs;
                }
            }
            first_part = false;
        }
    }

    if (first_part) {
        mp_printf(&mp_plat_print, "MPY: can't mount SD card\n");
        return false;
    } else {
        return true;
    }
}
#endif

#if defined(STM32N6)
static void risaf_init(void) {
    RIMC_MasterConfig_t rimc_master = {0};

    __HAL_RCC_RIFSC_CLK_ENABLE();
    LL_AHB3_GRP1_EnableClockLowPower(LL_AHB3_GRP1_PERIPH_RIFSC | LL_AHB3_GRP1_PERIPH_RISAF);

    rimc_master.MasterCID = RIF_CID_1;
    rimc_master.SecPriv = RIF_ATTRIBUTE_SEC | RIF_ATTRIBUTE_PRIV;

    HAL_RIF_RIMC_ConfigMasterAttributes(RIF_MASTER_INDEX_SDMMC1, &rimc_master);
    HAL_RIF_RISC_SetSlaveSecureAttributes(RIF_RISC_PERIPH_INDEX_SDMMC1, RIF_ATTRIBUTE_SEC | RIF_ATTRIBUTE_PRIV);
    HAL_RIF_RIMC_ConfigMasterAttributes(RIF_MASTER_INDEX_SDMMC2, &rimc_master);
    HAL_RIF_RISC_SetSlaveSecureAttributes(RIF_RISC_PERIPH_INDEX_SDMMC2, RIF_ATTRIBUTE_SEC | RIF_ATTRIBUTE_PRIV);
}
#endif

void stm32_main(uint32_t reset_mode) {
    // Low-level MCU initialisation.
    stm32_system_init();

    // Set VTOR, the location of the interrupt vector table.
    // On N6, SystemInit does this, setting VTOR to &g_pfnVectors.
    #if !defined(STM32F0) && !defined(STM32N6)
    #if MICROPY_HW_ENABLE_ISR_UART_FLASH_FUNCS_IN_RAM
    // Copy IRQ vector table to RAM and point VTOR there
    extern uint32_t __isr_vector_flash_addr, __isr_vector_ram_start, __isr_vector_ram_end;
    size_t __isr_vector_size = (&__isr_vector_ram_end - &__isr_vector_ram_start) * sizeof(uint32_t);
    memcpy(&__isr_vector_ram_start, &__isr_vector_flash_addr, __isr_vector_size);
    SCB->VTOR = (uint32_t)&__isr_vector_ram_start;
    #else
    #if defined(MICROPY_HW_VTOR)
    // Change IRQ vector table if configured differently
    SCB->VTOR = MICROPY_HW_VTOR;
    #endif
    #endif
    #endif

    #if __CORTEX_M != 33 && __CORTEX_M != 55
    // Enable 8-byte stack alignment for IRQ handlers, in accord with EABI
    SCB->CCR |= SCB_CCR_STKALIGN_Msk;
    #endif

    // Hook for a board to run code at start up, for example check if a
    // bootloader should be entered instead of the main application.
    MICROPY_BOARD_STARTUP();

    // Enable caches and prefetch buffers

    #if defined(STM32F4)

    #if INSTRUCTION_CACHE_ENABLE
    __HAL_FLASH_INSTRUCTION_CACHE_ENABLE();
    #endif
    #if DATA_CACHE_ENABLE
    __HAL_FLASH_DATA_CACHE_ENABLE();
    #endif
    #if PREFETCH_ENABLE
    __HAL_FLASH_PREFETCH_BUFFER_ENABLE();
    #endif

    #elif defined(STM32F7) || defined(STM32H7) || defined(STM32N6)

    #if ART_ACCLERATOR_ENABLE
    __HAL_FLASH_ART_ENABLE();
    #endif

    SCB_EnableICache();
    #if defined(STM32N6) && !defined(NDEBUG)
    // Don't enable D-cache on N6 when debugging; see ST Errata ES0620 - Rev 0.2 section 2.1.2.
    #else
    SCB_EnableDCache();
    #endif

    #elif defined(STM32H5)

    HAL_ICACHE_Enable();

    #elif defined(STM32L4)

    #if !INSTRUCTION_CACHE_ENABLE
    __HAL_FLASH_INSTRUCTION_CACHE_DISABLE();
    #endif
    #if !DATA_CACHE_ENABLE
    __HAL_FLASH_DATA_CACHE_DISABLE();
    #endif
    #if PREFETCH_ENABLE
    __HAL_FLASH_PREFETCH_BUFFER_ENABLE();
    #endif

    #endif

    #if defined(STM32N6)
    // SRAM, XSPI needs to remain awake during sleep, eg so DMA from flash works.
    LL_MEM_EnableClockLowPower(0xffffffff);
    LL_AHB5_GRP1_EnableClockLowPower(LL_AHB5_GRP1_PERIPH_XSPI2 | LL_AHB5_GRP1_PERIPH_XSPIM);
    LL_APB4_GRP1_EnableClock(LL_APB4_GRP1_PERIPH_RTC | LL_APB4_GRP1_PERIPH_RTCAPB);
    LL_APB4_GRP1_EnableClockLowPower(LL_APB4_GRP1_PERIPH_RTC | LL_APB4_GRP1_PERIPH_RTCAPB);

    // Enable some AHB peripherals during sleep.
    LL_AHB1_GRP1_EnableClockLowPower(0xffffffff); // GPDMA1, ADC12
    LL_AHB4_GRP1_EnableClockLowPower(0xffffffff); // GPIOA-Q, PWR, CRC

    // Enable some APB peripherals during sleep.
    LL_APB1_GRP1_EnableClockLowPower(0xffffffff); // I2C, I3C, LPTIM, SPI, TIM, UART, WWDG
    LL_APB2_GRP1_EnableClockLowPower(0xffffffff); // SAI, SPI, TIM, UART
    LL_APB4_GRP1_EnableClockLowPower(0xffffffff); // I2C, LPTIM, LPUART, RTC, SPI
    #endif

    mpu_init();

    #if __CORTEX_M >= 0x03
    // Set the priority grouping
    NVIC_SetPriorityGrouping(NVIC_PRIORITYGROUP_4);
    #endif

    // SysTick is needed by HAL_RCC_ClockConfig (called in SystemClock_Config)
    HAL_InitTick(TICK_INT_PRIORITY);

    // set the system clock to be HSE
    SystemClock_Config();

    #if defined(STM32N6)
    risaf_init();
    #endif

    #if defined(STM32F4) || defined(STM32F7)
    #if defined(__HAL_RCC_DTCMRAMEN_CLK_ENABLE)
    // The STM32F746 doesn't really have CCM memory, but it does have DTCM,
    // which behaves more or less like normal SRAM.
    __HAL_RCC_DTCMRAMEN_CLK_ENABLE();
    #elif defined(CCMDATARAM_BASE)
    // enable the CCM RAM
    __HAL_RCC_CCMDATARAMEN_CLK_ENABLE();
    #endif
    #elif defined(STM32H7A3xx) || defined(STM32H7A3xxQ) || defined(STM32H7B3xx) || defined(STM32H7B3xxQ)
    // Enable SRAM clock.
    __HAL_RCC_SRDSRAM_CLK_ENABLE();
    #elif defined(STM32H7)
    // Enable D2 SRAM1/2/3 clocks.
    __HAL_RCC_D2SRAM1_CLK_ENABLE();
    __HAL_RCC_D2SRAM2_CLK_ENABLE();
    #if defined(__HAL_RCC_D2SRAM3_CLK_ENABLE)
    __HAL_RCC_D2SRAM3_CLK_ENABLE();
    #endif
    #endif

    MICROPY_BOARD_EARLY_INIT();

    // basic sub-system init
    #if defined(STM32H5)
    volatile uint32_t *src = (volatile uint32_t *)UID_BASE;
    uint32_t *dest = (uint32_t *)&mp_hal_unique_id_address[0];
    dest[0] = src[0];
    dest[1] = src[1];
    dest[2] = src[2];
    #endif
    #if defined(STM32WB)
    rfcore_init();
    #endif
    #if defined(STM32WL)
    subghz_init();
    #endif
    #if MICROPY_HW_SDRAM_SIZE
    sdram_init();
    bool sdram_valid = true;
    UNUSED(sdram_valid);
    #if MICROPY_HW_SDRAM_STARTUP_TEST
    sdram_valid = sdram_test(false);
    #endif
    #endif
    #if MICROPY_PY_THREAD
    pyb_thread_init(&pyb_thread_main);
    #endif
    pendsv_init();
    led_init();
    #if MICROPY_HW_HAS_SWITCH
    switch_init0();
    #endif
    #if MICROPY_PY_MACHINE
    machine_init();
    #endif
    #if MICROPY_HW_ENABLE_RTC
    rtc_init_start(false);
    #endif
    uart_init0();

    #if defined(MICROPY_HW_UART_REPL)
    // Set up a UART REPL using a statically allocated object
    pyb_uart_repl_obj.base.type = &machine_uart_type;
    pyb_uart_repl_obj.uart_id = MICROPY_HW_UART_REPL;
    pyb_uart_repl_obj.is_static = true;
    pyb_uart_repl_obj.timeout = 0;
    pyb_uart_repl_obj.timeout_char = 2;
    uart_init(&pyb_uart_repl_obj, MICROPY_HW_UART_REPL_BAUD, UART_WORDLENGTH_8B, UART_PARITY_NONE, UART_STOPBITS_1, 0);
    uart_set_rxbuf(&pyb_uart_repl_obj, sizeof(pyb_uart_repl_rxbuf), pyb_uart_repl_rxbuf);
    uart_attach_to_repl(&pyb_uart_repl_obj, true);
    MP_STATE_PORT(machine_uart_obj_all)[MICROPY_HW_UART_REPL - 1] = &pyb_uart_repl_obj;
    MP_STATE_PORT(pyb_stdio_uart) = &pyb_uart_repl_obj;
    #endif

    spi_init0();
    #if MICROPY_PY_PYB_LEGACY && MICROPY_HW_ENABLE_HW_I2C
    i2c_init0();
    #endif
    #if MICROPY_HW_ENABLE_SDCARD || MICROPY_HW_ENABLE_MMCARD
    sdcard_init();
    #endif
    #if MICROPY_HW_ENABLE_STORAGE
    storage_init();
    #endif
    #if MICROPY_PY_LWIP
    // lwIP doesn't allow to reinitialise itself by subsequent calls to this function
    // because the system timeout list (next_timeout) is only ever reset by BSS clearing.
    // So for now we only init the lwIP stack once on power-up.
    lwip_init();
    #if LWIP_MDNS_RESPONDER
    mdns_resp_init();
    #endif
    systick_enable_dispatch(SYSTICK_DISPATCH_LWIP, mod_network_lwip_poll_wrapper);
    #endif
    #if MICROPY_PY_BLUETOOTH
    mp_bluetooth_hci_init();
    #endif

    #if MICROPY_PY_NETWORK_CYW43
    {
        cyw43_init(&cyw43_state);
        uint8_t buf[8];
        memcpy(&buf[0], "PYBD", 4);
        mp_hal_get_mac_ascii(MP_HAL_MAC_WLAN0, 8, 4, (char *)&buf[4]);
        cyw43_wifi_ap_set_ssid(&cyw43_state, 8, buf);
        cyw43_wifi_ap_set_auth(&cyw43_state, CYW43_AUTH_WPA2_MIXED_PSK);
        cyw43_wifi_ap_set_password(&cyw43_state, 8, (const uint8_t *)"pybd0123");
    }
    #endif

    boardctrl_state_t state;
    state.reset_mode = reset_mode;
    state.log_soft_reset = false;

    MICROPY_BOARD_BEFORE_SOFT_RESET_LOOP(&state);

soft_reset:

    MICROPY_BOARD_TOP_SOFT_RESET_LOOP(&state);

    // Python threading init
    #if MICROPY_PY_THREAD
    mp_thread_init();
    #endif

    // Stack limit init.
    mp_cstack_init_with_top(&_estack, (char *)&_estack - (char *)&_sstack);

    // GC init
    gc_init(MICROPY_HEAP_START, MICROPY_HEAP_END);

    // Add additional GC blocks (if enabled).
    #if MICROPY_GC_SPLIT_HEAP
    typedef struct {
        uint8_t *addr;
        uint32_t size;
    } gc_blocks_table_t;

    extern const gc_blocks_table_t _gc_blocks_table_start;
    extern const gc_blocks_table_t _gc_blocks_table_end;

    for (gc_blocks_table_t const *block = &_gc_blocks_table_start; block < &_gc_blocks_table_end; block++) {
        if (block->size) {
            gc_add(block->addr, block->addr + block->size);
        }
    }
    #endif

    #if MICROPY_ENABLE_PYSTACK
    static mp_obj_t pystack[384];
    mp_pystack_init(pystack, &pystack[384]);
    #endif

    // MicroPython init
    mp_init();

    // Initialise low-level sub-systems.  Here we need to very basic things like
    // zeroing out memory and resetting any of the sub-systems.  Following this
    // we can run Python scripts (eg boot.py), but anything that is configurable
    // by boot.py must be set after boot.py is run.

    readline_init0();
    pin_init0();
    extint_init0();
    timer_init0();

    #if MICROPY_HW_ENABLE_CAN
    pyb_can_init0();
    #endif

    #if MICROPY_HW_ENABLE_USB
    pyb_usb_init0();
    #endif

    #if MICROPY_PY_MACHINE_I2S
    machine_i2s_init0();
    #endif

    // Initialise the local flash filesystem.
    // Create it if needed, mount in on /flash, and set it as current dir.
    bool mounted_flash = false;
    #if MICROPY_HW_FLASH_MOUNT_AT_BOOT
    mounted_flash = init_flash_fs(state.reset_mode);
    #endif

    bool mounted_sdcard = false;
    #if MICROPY_HW_SDCARD_MOUNT_AT_BOOT
    // if an SD card is present then mount it on /sd/
    if (sdcard_is_present()) {
        // if there is a file in the flash called "SKIPSD", then we don't mount the SD card
        if (!mounted_flash || mp_vfs_import_stat("SKIPSD") == MP_IMPORT_STAT_NO_EXIST) {
            mounted_sdcard = init_sdcard_fs();
        }
    }
    #endif

    #if MICROPY_HW_ENABLE_USB
    // if the SD card isn't used as the USB MSC medium then use the internal flash
    if (pyb_usb_storage_medium == PYB_USB_STORAGE_MEDIUM_NONE) {
        pyb_usb_storage_medium = PYB_USB_STORAGE_MEDIUM_FLASH;
    }
    #endif

    // set sys.path based on mounted filesystems (/sd is first so it can override /flash)
    if (mounted_sdcard) {
        mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR__slash_sd));
        mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR__slash_sd_slash_lib));
    }
    if (mounted_flash) {
        mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR__slash_flash));
        mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR__slash_flash_slash_lib));
    }

    // reset config variables; they should be set by boot.py
    MP_STATE_PORT(pyb_config_main) = MP_OBJ_NULL;

    // Run optional frozen boot code.
    #ifdef MICROPY_BOARD_FROZEN_BOOT_FILE
    pyexec_frozen_module(MICROPY_BOARD_FROZEN_BOOT_FILE, false);
    #endif

    // Run boot.py (or whatever else a board configures at this stage).
    if (MICROPY_BOARD_RUN_BOOT_PY(&state) == BOARDCTRL_GOTO_SOFT_RESET_EXIT) {
        goto soft_reset_exit;
    }

    // Now we initialise sub-systems that need configuration from boot.py,
    // or whose initialisation can be safely deferred until after running
    // boot.py.

    #if MICROPY_HW_ENABLE_USB
    // init USB device to default setting if it was not already configured
    if (!(pyb_usb_flags & PYB_USB_FLAG_USB_MODE_CALLED)) {
        #if MICROPY_HW_USB_MSC
        const uint16_t pid = MICROPY_HW_USB_PID_CDC_MSC;
        const uint8_t mode = USBD_MODE_CDC_MSC;
        #else
        const uint16_t pid = MICROPY_HW_USB_PID_CDC;
        const uint8_t mode = USBD_MODE_CDC;
        #endif
        pyb_usb_dev_init(pyb_usb_dev_detect(), MICROPY_HW_USB_VID, pid, mode, 0, NULL, NULL);
    }
    #endif

    #if MICROPY_HW_HAS_MMA7660
    // MMA accel: init and reset
    accel_init();
    #endif

    #if MICROPY_HW_ENABLE_SERVO
    servo_init();
    #endif

    #if MICROPY_PY_NETWORK
    mod_network_init();
    #endif

    // At this point everything is fully configured and initialised.

    // Run main.py (or whatever else a board configures at this stage).
    if (MICROPY_BOARD_RUN_MAIN_PY(&state) == BOARDCTRL_GOTO_SOFT_RESET_EXIT) {
        goto soft_reset_exit;
    }

    #if MICROPY_ENABLE_COMPILER
    // Main script is finished, so now go into REPL mode.
    // The REPL mode can change, or it can request a soft reset.
    for (;;) {
        if (pyexec_mode_kind == PYEXEC_MODE_RAW_REPL) {
            if (pyexec_raw_repl() != 0) {
                break;
            }
        } else {
            if (pyexec_friendly_repl() != 0) {
                break;
            }
        }
    }
    #endif

soft_reset_exit:

    // soft reset

    MICROPY_BOARD_START_SOFT_RESET(&state);

    #if MICROPY_HW_ENABLE_STORAGE
    if (state.log_soft_reset) {
        mp_printf(&mp_plat_print, "MPY: sync filesystems\n");
    }
    storage_flush();
    #endif

    if (state.log_soft_reset) {
        mp_printf(&mp_plat_print, "MPY: soft reboot\n");
    }

    #if MICROPY_PY_BLUETOOTH
    mp_bluetooth_deinit();
    #endif
    #if defined(STM32WL)
    subghz_deinit();
    #endif
    #if MICROPY_PY_NETWORK
    mod_network_deinit();
    #endif
    soft_timer_deinit();
    timer_deinit();
    uart_deinit_all();
    spi_deinit_all();
    #if MICROPY_PY_PYB_LEGACY && MICROPY_HW_ENABLE_HW_I2C
    pyb_i2c_deinit_all();
    #endif
    #if MICROPY_PY_MACHINE_I2C_TARGET
    mp_machine_i2c_target_deinit_all();
    #endif
    #if MICROPY_HW_ENABLE_CAN
    pyb_can_deinit_all();
    #endif
    #if MICROPY_HW_ENABLE_DAC
    dac_deinit_all();
    #endif
    #if MICROPY_PY_MACHINE
    machine_deinit();
    #endif

    #if MICROPY_PY_THREAD
    pyb_thread_deinit();
    #endif

    #if defined(MICROPY_HW_UART_REPL)
    MP_STATE_PORT(pyb_stdio_uart) = &pyb_uart_repl_obj;
    #else
    MP_STATE_PORT(pyb_stdio_uart) = NULL;
    #endif

    MICROPY_BOARD_END_SOFT_RESET(&state);

    gc_sweep_all();
    mp_deinit();

    goto soft_reset;
}

MP_REGISTER_ROOT_POINTER(mp_obj_t pyb_config_main);