tinyusb example cdc_msc for STM32F042F6P6 with crystal-less oscillator

main.c

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2019 Ha Thach (tinyusb.org)
 *
 * 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 <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "tusb.h"
#include "main.h"

//--------------------------------------------------------------------+
// MACRO CONSTANT TYPEDEF PROTYPES
//--------------------------------------------------------------------+

/* Blink pattern
 * - 250 ms  : device not mounted
 * - 1000 ms : device mounted
 * - 2500 ms : device is suspended
 */
enum  {
  BLINK_NOT_MOUNTED = 250,
  BLINK_MOUNTED = 1000,
  BLINK_SUSPENDED = 2500,
};

static uint32_t blink_interval_ms = BLINK_NOT_MOUNTED;

void led_blinking_task(void);

void cdc_task(void);

void Error_Handler() {
	while (1);
}

void System_Config(void)
{
  SysTick_Config(SystemCoreClock / 1000);

  // enable clocks for pinswap
  __HAL_RCC_SYSCFG_CLK_ENABLE();
  __HAL_RCC_PWR_CLK_ENABLE();
  
  __HAL_REMAP_PIN_ENABLE(HAL_REMAP_PA11_PA12);

  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
  RCC_CRSInitTypeDef RCC_CRSInitStruct = {0};

  /** Initializes the CPU, AHB and APB busses clocks
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI48;
  RCC_OscInitStruct.HSI48State = RCC_HSI48_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the CPU, AHB and APB busses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI48;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
  {
    Error_Handler();
  }
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USB;
  PeriphClkInit.UsbClockSelection = RCC_USBCLKSOURCE_HSI48;

  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    Error_Handler();
  }
  /** Enable the SYSCFG APB clock
  */

  __HAL_RCC_CRS_CLK_ENABLE();

  /** Configures CRS
  */
  RCC_CRSInitStruct.Prescaler = RCC_CRS_SYNC_DIV1;
  RCC_CRSInitStruct.Source = RCC_CRS_SYNC_SOURCE_USB;
  RCC_CRSInitStruct.Polarity = RCC_CRS_SYNC_POLARITY_RISING;
  RCC_CRSInitStruct.ReloadValue = __HAL_RCC_CRS_RELOADVALUE_CALCULATE(48000000,1000);
  RCC_CRSInitStruct.ErrorLimitValue = 34;
  RCC_CRSInitStruct.HSI48CalibrationValue = 32;

  HAL_RCCEx_CRSConfig(&RCC_CRSInitStruct);

  // recalc clock
  SystemCoreClockUpdate();

  // enable GPIO and USB clocks, D-/D+ are on GPIOA
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_USB_CLK_ENABLE();
}

volatile uint32_t system_ticks = 0;
void SysTick_Handler (void)
{
  system_ticks++;
}

uint32_t board_millis(void)
{
  return system_ticks;
}

/*------------- MAIN -------------*/
int main(void)
{
  System_Config();
  tusb_init();

  while (1)
  {
    tud_task(); // tinyusb device task
    led_blinking_task();

    cdc_task();
  }

  return 0;
}

//--------------------------------------------------------------------+
// Device callbacks
//--------------------------------------------------------------------+

// Invoked when device is mounted
void tud_mount_cb(void)
{
  blink_interval_ms = BLINK_MOUNTED;
}

// Invoked when device is unmounted
void tud_umount_cb(void)
{
  blink_interval_ms = BLINK_NOT_MOUNTED;
}

// Invoked when usb bus is suspended
// remote_wakeup_en : if host allow us  to perform remote wakeup
// Within 7ms, device must draw an average of current less than 2.5 mA from bus
void tud_suspend_cb(bool remote_wakeup_en)
{
  (void) remote_wakeup_en;
  blink_interval_ms = BLINK_SUSPENDED;
}

// Invoked when usb bus is resumed
void tud_resume_cb(void)
{
  blink_interval_ms = BLINK_MOUNTED;
}


//--------------------------------------------------------------------+
// USB CDC
//--------------------------------------------------------------------+
void cdc_task(void)
{
  if ( tud_cdc_connected() )
  {
    // connected and there are data available
    if ( tud_cdc_available() )
    {
      uint8_t buf[64];

      // read and echo back
      uint32_t count = tud_cdc_read(buf, sizeof(buf));

      for(uint32_t i=0; i<count; i++)
      {
        tud_cdc_write_char(buf[i]);

        if ( buf[i] == '\r' ) tud_cdc_write_char('\n');
      }

      tud_cdc_write_flush();
    }
  }
}

// Invoked when cdc when line state changed e.g connected/disconnected
void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts)
{
  (void) itf;

  // connected
  if ( dtr && rts )
  {
    // print initial message when connected
    tud_cdc_write_str("\r\nTinyUSB CDC MSC device example\r\n");
  }
}

// Invoked when CDC interface received data from host
void tud_cdc_rx_cb(uint8_t itf)
{
  (void) itf;
}

//--------------------------------------------------------------------+
// BLINKING TASK
//--------------------------------------------------------------------+
void led_blinking_task(void)
{
  static uint32_t start_ms = 0;
  static bool led_state = false;

  // Blink every interval ms
  if ( board_millis() - start_ms < blink_interval_ms) return; // not enough time
  start_ms += blink_interval_ms;

  led_state = 1 - led_state; // toggle
}