【瑞萨RA4系列开发板体验】3 GPIO流水灯的前生今世

**开发环境：**

开发环境：

IDE：MKD 5.30

开发板：RA-Eco-RA4M2

MCU：R7FA4M2AD3CFP

上一章通过控制GPIO的高低电平实现了流水灯，但只是告诉了大家怎么做，如何实现流水灯，本文将深入剖析的GPIO流水灯的前生今世，深入研究流水灯的调用逻辑和数据结构。

1 GPIO配置概述

前面一章大概讲解GPIO流水灯，关于GPIO的内容很多，具体请参看《RA4M2 Group User’s Manual Hardware》中I/O Ports相关的章节吧。

1669539201732qv8mv3p84h

要想控制LED亮灭，就需要做以上三件事：使能时钟，配置GPIO参数，最后循环控制GPIO的高低电平就能实现流水灯的效果，GPIO的寄存器这里就不说了，更多详细的寄存器描述看官方手册就行，下面先来看看RA4M2的时钟。

2 RA4M2的时钟系统

2.1 RA4M2时钟架构

时钟是整个处理器运行的基础，时钟信号推动处理器内各个部分执行相应的指令。时钟系统就是CPU的脉搏，决定CPU速率，像人的心跳一样只有有了心跳，人才能做其他的事情，而单片机有了时钟，才能够运行执行指令，才能够做其他的处理 (点灯，串口，ADC)，时钟的重要性不言而喻。

RA4M2相对Cortex-3内核系列的MCU更为复杂，不仅是外设非常多，就连时钟来源就有8个之多。但我们实际使用的时候只会用到有限的几个外设，使用任何外设都需要时钟才能启动，但并不是所有的外设都需要系统时钟那么高的频率，为了兼容不同速度的设备，有些高速，有些低速，如果都用高速时钟，势必造成浪费，而且，同一个电路，时钟越快功耗越快，同时抗电磁干扰能力也就越弱，所以较为复杂的MCU都是采用多时钟源的方法来解决这些问题，因此便有了RA4M2的时钟系统和时钟树。

1669539202578d63eeu8ul0

RA4M2不同的时钟源可以用来驱动系统时钟(SCK)：

● MOSC(Main Clock Oscillator)：主时钟振荡器，连接外部 8 ~ 24 MHz 高速晶振

● SOSC(Sub-Clock Oscillator)：副时钟振荡器，连接外部 32.768 kHz 低速晶振(高速外部时钟信号)

● HOCO(High-speed on-chip oscillator)：高速片上振荡器，振荡频率: 16/18/20 MHz

● MOCO(Middle-speed on-chip oscillator)：中速片上振荡器，振荡频率: 8 MHz

● LOCO(Low-speed on-chip oscillator)：低速片上振荡器，振荡频率: 32.768 kHz

● PLL(Phase Locked Loop): 锁相环时钟，可以对输入时钟进行分频和倍频的功能，PLL 输出频率：100 MHz ~ 200 MHz，PLL2 输出频率：120 MHz ~ 240 MHz

RA4M2有两个二级时钟源：

● IWDTLOCO(IWDT-dedicated clock) ：IWDT专用片上振荡器，振荡频率: 15 kHz

● TCK/SWCLK(External clock input for JTAG/ External clock input for SWD) ：JTAG/SWD的外部时钟输入，振荡频率: 最大25MHz

每个时钟源在不使用时都可以单独被打开或关闭，这样就可以优化系统功耗。

2.2 RA4M2的时钟系统

RA4M2芯片为了实现低功耗，设计了一个功能完善但却非常复杂的时钟系统。普通的MCU 一般只要配置好 GPIO 的寄存器就可以使用了，但 RA4M2还有一个步骤，就是开启外设时钟。

在 RA4M2中，系统时钟源有很多，从来源可分为外部时钟源和内部时钟源，外部时钟源就是从外部通过接晶振的方式获取时钟源，其中 XTAL、XCIN和TCK/SWCLK是外部时钟源，其他的是内部时钟源。

下面我们看看RA4M2的系统时钟源，我们讲解顺序是按图中红圈标示的顺序：

MOSC是高速外部时钟，可接石英/陶瓷谐振器，或者接外部时钟源，频率范围为8MHz~24MHz。我们的开发板接的是24M的晶振。

SOSC是副时钟振荡器，接频率为 32.768kHz 的石英晶体。这个主要是 RTC 的时钟源。

HOCO是高速内部时钟，高速片上振荡器，振荡频率: 16/18/20 MHz。

MOCO是中速片上振荡器，振荡频率为8 MHz。

LOCO是低速片上振荡器，振荡频率为32.768 kHz。

PLL 为锁相环倍频输出，其时钟输入源可选择为MOSC、HOCO。倍频可选择为10~30倍，但是PLL输出频率最大不得超过 200MHz，PLL2输出频率最大不得超过 240MHz。

$C:\Users\BruceOu\Desktop\222222.png$

图中我们用 A~C标示就是系统时钟进过系统时钟主要流向的地方。

A. 此处是FCLK，最高50MHz.

B. B处就是 RA4M2的系统时钟 ICLK，它是供 RA4M2内核中绝大部分部件工作的时钟源，分别是CPU、DMAC、DTC、闪存和 SRAM。系统时钟可选择HCOC、MCOC、LOCO、XTAL、SUBCLK、PLL作为时钟源。系统时钟最大频率为 100MHz，当然你也可以超频，不过一般情况为了系统稳定性是没有必要冒风险去超频的。

C. 这里的C处是大部分外设的时钟输入源了。从时钟图上可以看出，其他所有外设的时钟最终来源都是 SCK。SCK 通过分频器分频后送给各模块使用。

3 RA4M2的时钟配置剖析

主频的时钟为默认的 200 MHz，来源是MOSC的24MHz时钟，经过PLL倍频，流向系统时钟。详细请查看RA Smart Configurator文件的配置。

1669539204323ib03y6el0l

当系统复位后就会进入Reset_Handler() -> SystemInit() -> bsp_clock_init()，bsp_clock_init()函数就是整个系统时钟的初始化部分，重点看这里，代码如下：

[文件路径: ra\fsp\src\bsp\mcu\all\bsp_clocks.c]

/*******************************************************************************************************************//**
 * Initializes system clocks.  Makes no assumptions about current register settings.
 **********************************************************************************************************************/
void bsp_clock_init (void)
{
    /* Unlock CGC and LPM protection registers. */
    R_SYSTEM->PRCR = (uint16_t) BSP_PRV_PRCR_UNLOCK;

#if BSP_FEATURE_BSP_FLASH_CACHE
 #if !BSP_CFG_USE_LOW_VOLTAGE_MODE && BSP_FEATURE_BSP_FLASH_CACHE_DISABLE_OPM

    /* Disable flash cache before modifying MEMWAIT, SOPCCR, or OPCCR. */
    R_BSP_FlashCacheDisable();
 #else

    /* Enable the flash cache and don't disable it while running from flash. On these MCUs, the flash cache does not
     * need to be disabled when adjusting the operating power mode. */
    R_BSP_FlashCacheEnable();
 #endif
#endif

#if BSP_FEATURE_BSP_FLASH_PREFETCH_BUFFER

    /* Disable the flash prefetch buffer. */
    R_FACI_LP->PFBER = 0;
#endif

    bsp_clock_freq_var_init();

#if BSP_CLOCK_CFG_MAIN_OSC_POPULATED
 #if BSP_CFG_STARTUP_CLOCK_REG_NOT_RESET

    /* Update the main oscillator drive, source, and wait states if the main oscillator is stopped.  If the main
     * oscillator is running, the drive, source, and wait states are assumed to be already set appropriately. */
    if (R_SYSTEM->MOSCCR)
    {
        /* Don't write to MOSCWTCR unless MOSTP is 1 and MOSCSF = 0. */
        FSP_HARDWARE_REGISTER_WAIT(R_SYSTEM->OSCSF_b.MOSCSF, 0U);

        /* Configure main oscillator drive. */
        R_SYSTEM->MOMCR = BSP_PRV_MOMCR;

        /* Set the main oscillator wait time. */
        R_SYSTEM->MOSCWTCR = (uint8_t) BSP_CLOCK_CFG_MAIN_OSC_WAIT;
    }

 #else

    /* Configure main oscillator drive. */
    R_SYSTEM->MOMCR = BSP_PRV_MOMCR;

    /* Set the main oscillator wait time. */
    R_SYSTEM->MOSCWTCR = (uint8_t) BSP_CLOCK_CFG_MAIN_OSC_WAIT;
 #endif
#endif

#if BSP_FEATURE_CGC_HAS_SOSC
 #if BSP_CLOCK_CFG_SUBCLOCK_POPULATED

    /* If Sub-Clock Oscillator is started at reset, stop it before configuring the subclock drive. */
    if (0U == R_SYSTEM->SOSCCR)
    {
        /* Stop the Sub-Clock Oscillator to update the SOMCR register. */
        R_SYSTEM->SOSCCR = 1U;

        /* Allow a stop interval of at least 5 SOSC clock cycles before configuring the drive capacity
         * and restarting Sub-Clock Oscillator. */
        R_BSP_SoftwareDelay(BSP_PRV_SUBCLOCK_STOP_INTERVAL_US, BSP_DELAY_UNITS_MICROSECONDS);
    }

    /* Configure the subclock drive as subclock is not running. */
    R_SYSTEM->SOMCR = ((BSP_CLOCK_CFG_SUBCLOCK_DRIVE << BSP_FEATURE_CGC_SODRV_SHIFT) & BSP_FEATURE_CGC_SODRV_MASK);

    /* Restart the Sub-Clock Oscillator. */
    R_SYSTEM->SOSCCR = 0U;
  #if (BSP_CLOCKS_SOURCE_CLOCK_SUBCLOCK == BSP_CFG_CLOCK_SOURCE) || (BSP_PRV_HOCO_USE_FLL)

    /* If the subclock is the system clock source OR if FLL is used, wait for stabilization. */
    R_BSP_SubClockStabilizeWait(BSP_CLOCK_CFG_SUBCLOCK_STABILIZATION_MS);
  #endif
 #else
    R_SYSTEM->SOSCCR = 1U;
 #endif
#endif

#if BSP_FEATURE_CGC_HAS_HOCOWTCR
 #if BSP_FEATURE_CGC_HOCOWTCR_64MHZ_ONLY

    /* These MCUs only require writes to HOCOWTCR if HOCO is set to 64 MHz. */
  #if 64000000 == BSP_HOCO_HZ
   #if BSP_CFG_USE_LOW_VOLTAGE_MODE

    /* Wait for HOCO to stabilize before writing to HOCOWTCR. */
    FSP_HARDWARE_REGISTER_WAIT(R_SYSTEM->OSCSF_b.HOCOSF, 1U);
   #else

    /* HOCO is assumed to be stable because these MCUs also require the HOCO to be stable before changing the operating
     * power control mode. */
   #endif
    R_SYSTEM->HOCOWTCR = BSP_FEATURE_CGC_HOCOWTCR_VALUE;
  #endif
 #else

    /* These MCUs require HOCOWTCR to be set to the maximum value except in snooze mode.  There is no restriction to
     * writing this register. */
    R_SYSTEM->HOCOWTCR = BSP_FEATURE_CGC_HOCOWTCR_VALUE;
 #endif
#endif

#if !BSP_CFG_USE_LOW_VOLTAGE_MODE
 #if BSP_CFG_STARTUP_CLOCK_REG_NOT_RESET

    /* Switch to high-speed to prevent any issues with the subsequent clock configurations. */
    bsp_prv_operating_mode_set(BSP_PRV_OPERATING_MODE_HIGH_SPEED);
 #elif BSP_FEATURE_CGC_LOW_VOLTAGE_MAX_FREQ_HZ > 0U

    /* MCUs that support low voltage mode start up in low voltage mode. */
    bsp_prv_operating_mode_opccr_set(BSP_PRV_OPERATING_MODE_HIGH_SPEED);

  #if !BSP_PRV_HOCO_USED

    /* HOCO must be running during startup in low voltage mode. If HOCO is not used, turn it off after exiting low
     * voltage mode. */
    R_SYSTEM->HOCOCR = 1U;
  #endif
 #elif BSP_FEATURE_CGC_STARTUP_OPCCR_MODE != BSP_PRV_OPERATING_MODE_HIGH_SPEED

    /* Some MCUs do not start in high speed mode. */
    bsp_prv_operating_mode_opccr_set(BSP_PRV_OPERATING_MODE_HIGH_SPEED);
 #endif
#endif

    /* The FLL function can only be used when the subclock is running. */
#if BSP_PRV_HOCO_USE_FLL

    /* If FLL is to be used configure FLLCR1 and FLLCR2 before starting HOCO. */
    R_SYSTEM->FLLCR2 = BSP_PRV_FLL_FLLCR2;
    R_SYSTEM->FLLCR1 = 1U;
#endif

    /* Start all clocks used by other clocks first. */
#if BSP_PRV_HOCO_USED
    R_SYSTEM->HOCOCR = 0U;

 #if BSP_PRV_HOCO_USE_FLL && (BSP_CLOCKS_SOURCE_CLOCK_HOCO != BSP_CFG_PLL_SOURCE)

    /* If FLL is enabled, wait for the FLL stabilization delay (1.8 ms) */
    R_BSP_SoftwareDelay(BSP_PRV_FLL_STABILIZATION_TIME_US, BSP_DELAY_UNITS_MICROSECONDS);
 #endif

 #if BSP_PRV_STABILIZE_HOCO

    /* Wait for HOCO to stabilize. */
    FSP_HARDWARE_REGISTER_WAIT(R_SYSTEM->OSCSF_b.HOCOSF, 1U);
 #endif
#endif
#if BSP_PRV_MOCO_USED
 #if BSP_CFG_STARTUP_CLOCK_REG_NOT_RESET

    /* If the MOCO is not running, start it and wait for it to stabilize using a software delay. */
    if (0U != R_SYSTEM->MOCOCR)
    {
        R_SYSTEM->MOCOCR = 0U;
  #if BSP_PRV_STABILIZE_MOCO
        R_BSP_SoftwareDelay(BSP_FEATURE_CGC_MOCO_STABILIZATION_MAX_US, BSP_DELAY_UNITS_MICROSECONDS);
  #endif
    }
 #endif
#endif
#if BSP_PRV_LOCO_USED
 #if BSP_CFG_STARTUP_CLOCK_REG_NOT_RESET

    /* If the LOCO is not running, start it and wait for it to stabilize using a software delay. */
    if (0U != R_SYSTEM->LOCOCR)
    {
        R_SYSTEM->LOCOCR = 0U;
  #if BSP_PRV_STABILIZE_LOCO
        R_BSP_SoftwareDelay(BSP_FEATURE_CGC_LOCO_STABILIZATION_MAX_US, BSP_DELAY_UNITS_MICROSECONDS);
  #endif
    }

 #else
    R_SYSTEM->LOCOCR = 0U;
  #if BSP_PRV_STABILIZE_LOCO
    R_BSP_SoftwareDelay(BSP_FEATURE_CGC_LOCO_STABILIZATION_MAX_US, BSP_DELAY_UNITS_MICROSECONDS);
  #endif
 #endif
#endif
#if BSP_PRV_MAIN_OSC_USED
    R_SYSTEM->MOSCCR = 0U;

 #if BSP_PRV_STABILIZE_MAIN_OSC

    /* Wait for main oscillator to stabilize. */
    FSP_HARDWARE_REGISTER_WAIT(R_SYSTEM->OSCSF_b.MOSCSF, 1U);
 #endif
#endif

    /* Start clocks that require other clocks. At this point, all dependent clocks are running and stable if needed. */

#if BSP_PRV_STARTUP_OPERATING_MODE != BSP_PRV_OPERATING_MODE_LOW_SPEED
 #if BSP_FEATURE_CGC_HAS_PLL2 && BSP_CFG_PLL2_SOURCE != BSP_CLOCKS_CLOCK_DISABLED
    R_SYSTEM->PLL2CCR = BSP_PRV_PLL2CCR;
  #if (3U == BSP_FEATURE_CGC_PLLCCR_TYPE)
    R_SYSTEM->PLL2CCR2 = BSP_PRV_PLL2CCR2;
  #endif

    /* Start PLL2. */
    R_SYSTEM->PLL2CR = 0U;
 #endif                                /* BSP_FEATURE_CGC_HAS_PLL2 && BSP_CFG_PLL2_ENABLE */
#endif

#if BSP_PRV_PLL_SUPPORTED && BSP_PRV_PLL_USED
 #if BSP_CLOCKS_SOURCE_CLOCK_PLL == BSP_CFG_CLOCK_SOURCE

    /* Configure the PLL registers. */
  #if 1U == BSP_FEATURE_CGC_PLLCCR_TYPE
    R_SYSTEM->PLLCCR = (uint16_t) BSP_PRV_PLLCCR;
  #elif 2U == BSP_FEATURE_CGC_PLLCCR_TYPE
    R_SYSTEM->PLLCCR2 = (uint8_t) BSP_PRV_PLLCCR;
  #elif 3U == BSP_FEATURE_CGC_PLLCCR_TYPE
    R_SYSTEM->PLLCCR  = (uint16_t) BSP_PRV_PLLCCR;
    R_SYSTEM->PLLCCR2 = (uint16_t) BSP_PRV_PLLCCR2;
  #endif

  #if BSP_FEATURE_CGC_PLLCCR_WAIT_US > 0

    /* This loop is provided to ensure at least 1 us passes between setting PLLMUL and clearing PLLSTP on some
     * MCUs (see PLLSTP notes in Section 8.2.4 "PLL Control Register (PLLCR)" of the RA4M1 manual R01UH0887EJ0100).
     * Five loops are needed here to ensure the most efficient path takes at least 1 us from the setting of
     * PLLMUL to the clearing of PLLSTP. HOCO is the fastest clock we can be using here since PLL cannot be running
     * while setting PLLCCR. */
    bsp_prv_software_delay_loop(BSP_DELAY_LOOPS_CALCULATE(BSP_PRV_MAX_HOCO_CYCLES_PER_US));
  #endif
 #endif

    R_SYSTEM->PLLCR = 0U;

 #if BSP_PRV_STABILIZE_PLL

    /* Wait for PLL to stabilize. */
    FSP_HARDWARE_REGISTER_WAIT(R_SYSTEM->OSCSF_b.PLLSF, 1U);
 #endif
#endif

    /* Set source clock and dividers. */
#if BSP_CFG_STARTUP_CLOCK_REG_NOT_RESET
 #if BSP_TZ_SECURE_BUILD

    /* In case of soft reset, make sure callback pointer is NULL initially. */
    g_bsp_clock_update_callback = NULL;
 #endif

 #if BSP_FEATURE_CGC_HAS_CPUCLK
    bsp_prv_clock_set(BSP_CFG_CLOCK_SOURCE, BSP_PRV_STARTUP_SCKDIVCR, BSP_PRV_STARTUP_SCKDIVCR2);
 #else
    bsp_prv_clock_set(BSP_CFG_CLOCK_SOURCE, BSP_PRV_STARTUP_SCKDIVCR, 0);
 #endif
#else
    bsp_prv_clock_set_hard_reset();
#endif

    /* If the MCU can run in a lower power mode, apply the optimal operating speed mode. */
#if !BSP_CFG_USE_LOW_VOLTAGE_MODE
 #if BSP_PRV_STARTUP_OPERATING_MODE != BSP_PRV_OPERATING_MODE_HIGH_SPEED
  #if BSP_PRV_PLL_SUPPORTED
   #if BSP_CFG_STARTUP_CLOCK_REG_NOT_RESET
    if (BSP_PRV_OPERATING_MODE_LOW_SPEED == BSP_PRV_STARTUP_OPERATING_MODE)
    {
        /* If the MCU has a PLL, ensure PLL is stopped and stable before entering low speed mode. */
        R_SYSTEM->PLLCR = 1U;

        /* Wait for PLL to stabilize. */
        FSP_HARDWARE_REGISTER_WAIT(R_SYSTEM->OSCSF_b.PLLSF, 0U);

    #if BSP_FEATURE_CGC_HAS_PLL2

        /* If the MCU has a PLL2, ensure PLL2 is stopped and stable before entering low speed mode. */
        R_SYSTEM->PLL2CR = 1U;

        /* Wait for PLL to stabilize. */
        FSP_HARDWARE_REGISTER_WAIT(R_SYSTEM->OSCSF_b.PLL2SF, 0U);
    #endif
    }
   #endif
  #endif
    bsp_prv_operating_mode_set(BSP_PRV_STARTUP_OPERATING_MODE);
 #endif
#endif

#if defined(BSP_PRV_POWER_USE_DCDC) && (BSP_PRV_POWER_USE_DCDC == BSP_PRV_POWER_DCDC_STARTUP) && \
    (BSP_PRV_STARTUP_OPERATING_MODE <= BSP_PRV_OPERATING_MODE_MIDDLE_SPEED)

    /* Start DCDC as part of BSP startup when configured (BSP_CFG_DCDC_ENABLE == 2). */
    R_BSP_PowerModeSet(BSP_CFG_DCDC_VOLTAGE_RANGE);
#endif

    /* Configure BCLK if it exists on the MCU. */
#ifdef BSP_CFG_BCLK_OUTPUT
 #if BSP_CFG_BCLK_OUTPUT > 0U
    R_SYSTEM->BCKCR   = BSP_CFG_BCLK_OUTPUT - 1U;
    R_SYSTEM->EBCKOCR = 1U;
 #else
  #if BSP_CFG_STARTUP_CLOCK_REG_NOT_RESET
    R_SYSTEM->EBCKOCR = 0U;
  #endif
 #endif
#endif

    /* Configure SDRAM clock if it exists on the MCU. */
#ifdef BSP_CFG_SDCLK_OUTPUT
    R_SYSTEM->SDCKOCR = BSP_CFG_SDCLK_OUTPUT;
#endif

    /* Configure CLKOUT. */
#if BSP_CFG_CLKOUT_SOURCE == BSP_CLOCKS_CLOCK_DISABLED
 #if BSP_CFG_STARTUP_CLOCK_REG_NOT_RESET
    R_SYSTEM->CKOCR = 0U;
 #endif
#else
    uint8_t ckocr = BSP_CFG_CLKOUT_SOURCE | (BSP_CFG_CLKOUT_DIV << BSP_PRV_CKOCR_CKODIV_BIT);
    R_SYSTEM->CKOCR = ckocr;
    ckocr          |= (1U << BSP_PRV_CKOCR_CKOEN_BIT);
    R_SYSTEM->CKOCR = ckocr;
#endif

#if BSP_PRV_STARTUP_OPERATING_MODE != BSP_PRV_OPERATING_MODE_LOW_SPEED
 #if BSP_CFG_UCK_SOURCE != BSP_CLOCKS_CLOCK_DISABLED

    /* If the USB clock has a divider setting in SCKDIVCR2. */
  #if BSP_FEATURE_BSP_HAS_USB_CLOCK_DIV && !BSP_FEATURE_BSP_HAS_USBCKDIVCR
    R_SYSTEM->SCKDIVCR2 = BSP_PRV_UCK_DIV << BSP_PRV_SCKDIVCR2_UCK_BIT;
  #endif                               /* BSP_FEATURE_BSP_HAS_USB_CLOCK_DIV && !BSP_FEATURE_BSP_HAS_USBCKDIVCR */

    /* If there is a REQ bit in USBCKCR than follow sequence from section 8.2.29 in RA6M4 hardware manual R01UH0890EJ0050. */
  #if BSP_FEATURE_BSP_HAS_USB_CLOCK_REQ

    /* Request to change the USB Clock. */
    R_SYSTEM->USBCKCR_b.USBCKSREQ = 1;

    /* Wait for the clock to be stopped. */
    FSP_HARDWARE_REGISTER_WAIT(R_SYSTEM->USBCKCR_b.USBCKSRDY, 1U);

    /* Write the settings. */
    R_SYSTEM->USBCKDIVCR = BSP_PRV_UCK_DIV;

    /* Select the USB Clock without enabling it. */
    R_SYSTEM->USBCKCR = BSP_CFG_UCK_SOURCE | R_SYSTEM_USBCKCR_USBCKSREQ_Msk;
  #endif                               /* BSP_FEATURE_BSP_HAS_USB_CLOCK_REQ */

  #if BSP_FEATURE_BSP_HAS_USB_CLOCK_SEL

    /* Some MCUs use an alternate register for selecting the USB clock source. */
   #if BSP_FEATURE_BSP_HAS_USB_CLOCK_SEL_ALT
    #if BSP_CLOCKS_SOURCE_CLOCK_PLL == BSP_CFG_UCK_SOURCE

    /* Write to USBCKCR to select the PLL. */
    R_SYSTEM->USBCKCR_ALT = 0;
    #elif BSP_CLOCKS_SOURCE_CLOCK_HOCO == BSP_CFG_UCK_SOURCE

    /* Write to USBCKCR to select the HOCO. */
    R_SYSTEM->USBCKCR_ALT = 1;
    #endif
   #else

    /* Select the USB Clock. */
    R_SYSTEM->USBCKCR = BSP_CFG_UCK_SOURCE;
   #endif
  #endif                               /* BSP_FEATURE_BSP_HAS_USB_CLOCK_REQ */

  #if BSP_FEATURE_BSP_HAS_USB_CLOCK_REQ

    /* Wait for the USB Clock to be started. */
    FSP_HARDWARE_REGISTER_WAIT(R_SYSTEM->USBCKCR_b.USBCKSRDY, 0U);
  #endif                               /* BSP_FEATURE_BSP_HAS_USB_CLOCK_REQ */
 #endif                                /* BSP_CFG_USB_ENABLE */
#endif                                 /* BSP_PRV_STARTUP_OPERATING_MODE != BSP_PRV_OPERATING_MODE_LOW_SPEED */

    /* Set the OCTASPI clock if it exists on the MCU (See section 8.2.30 of the RA6M4 hardware manual R01UH0890EJ0050). */
#if BSP_FEATURE_BSP_HAS_OCTASPI_CLOCK && BSP_CFG_OCTA_SOURCE != BSP_CLOCKS_CLOCK_DISABLED
    bsp_octaclk_settings_t octaclk_settings =
    {
        .source_clock = (bsp_clocks_source_t) BSP_CFG_OCTA_SOURCE,
        .divider      = (bsp_clocks_octaclk_div_t) BSP_CFG_OCTA_DIV
    };
    R_BSP_OctaclkUpdate(&octaclk_settings);
#endif                                 /* BSP_FEATURE_BSP_HAS_OCTASPI_CLOCK && BSP_CFG_OCTASPI_CLOCK_ENABLE */

    /* Set the CANFD clock if it exists on the MCU */
#if BSP_FEATURE_BSP_HAS_CANFD_CLOCK && (BSP_CFG_CANFDCLK_SOURCE != BSP_CLOCKS_CLOCK_DISABLED) && \
    (BSP_CFG_CANFDCLK_SOURCE != BSP_CLOCKS_SOURCE_CLOCK_MAIN_OSC)

    bsp_peripheral_clock_set(&R_SYSTEM->CANFDCKCR,
                             &R_SYSTEM->CANFDCKDIVCR,
                             BSP_CFG_CANFDCLK_DIV,
                             BSP_CFG_CANFDCLK_SOURCE);
#endif

    /* Set the SCISPI clock if it exists on the MCU */
#if BSP_FEATURE_BSP_HAS_SCISPI_CLOCK && (BSP_CFG_SCISPICLK_SOURCE != BSP_CLOCKS_CLOCK_DISABLED)
    bsp_peripheral_clock_set(&R_SYSTEM->SCISPICKCR,
                             &R_SYSTEM->SCISPICKDIVCR,
                             BSP_CFG_SCISPICLK_DIV,
                             BSP_CFG_SCISPICLK_SOURCE);
#endif

    /* Set the SCI clock if it exists on the MCU */
#if BSP_FEATURE_BSP_HAS_SCI_CLOCK && (BSP_CFG_SCICLK_SOURCE != BSP_CLOCKS_CLOCK_DISABLED)
    bsp_peripheral_clock_set(&R_SYSTEM->SCICKCR, &R_SYSTEM->SCICKDIVCR, BSP_CFG_SCICLK_DIV, BSP_CFG_SCICLK_SOURCE);
#endif

    /* Set the SPI clock if it exists on the MCU */
#if BSP_FEATURE_BSP_HAS_SPI_CLOCK && (BSP_CFG_SPICLK_SOURCE != BSP_CLOCKS_CLOCK_DISABLED)
    bsp_peripheral_clock_set(&R_SYSTEM->SPICKCR, &R_SYSTEM->SPICKDIVCR, BSP_CFG_SPICLK_DIV, BSP_CFG_SPICLK_SOURCE);
#endif

    /* Set the GPT clock if it exists on the MCU */
#if BSP_FEATURE_BSP_HAS_GPT_CLOCK && (BSP_CFG_GPTCLK_SOURCE != BSP_CLOCKS_CLOCK_DISABLED)
    bsp_peripheral_clock_set(&R_SYSTEM->GPTCKCR, &R_SYSTEM->GPTCKDIVCR, BSP_CFG_GPTCLK_DIV, BSP_CFG_GPTCLK_SOURCE);
#endif

    /* Set the IIC clock if it exists on the MCU */
#if BSP_FEATURE_BSP_HAS_IIC_CLOCK && (BSP_CFG_IICCLK_SOURCE != BSP_CLOCKS_CLOCK_DISABLED)
    bsp_peripheral_clock_set(&R_SYSTEM->IICCKCR, &R_SYSTEM->IICCKDIVCR, BSP_CFG_IICCLK_DIV, BSP_CFG_IICCLK_SOURCE);
#endif

    /* Set the I3C clock if it exists on the MCU */
#if BSP_FEATURE_BSP_HAS_I3C_CLOCK && (BSP_CFG_I3CCLK_SOURCE != BSP_CLOCKS_CLOCK_DISABLED)
    bsp_peripheral_clock_set(&R_SYSTEM->I3CCKCR, &R_SYSTEM->I3CCKDIVCR, BSP_CFG_I3CCLK_DIV, BSP_CFG_I3CCLK_SOURCE);
#endif

    /* Set the ADC clock if it exists on the MCU */
#if BSP_FEATURE_BSP_HAS_ADC_CLOCK && (BSP_CFG_ADCCLK_SOURCE != BSP_CLOCKS_CLOCK_DISABLED)
    bsp_peripheral_clock_set(&R_SYSTEM->ADCCKCR, &R_SYSTEM->ADCCKDIVCR, BSP_CFG_ADCCLK_DIV, BSP_CFG_ADCCLK_SOURCE);
#endif

    /* Set the LCD clock if it exists on the MCU */
#if BSP_FEATURE_BSP_HAS_LCD_CLOCK && (BSP_CFG_LCDCLK_SOURCE != BSP_CLOCKS_CLOCK_DISABLED)
    bsp_peripheral_clock_set(&R_SYSTEM->LCDCKCR, &R_SYSTEM->LCDCKDIVCR, BSP_CFG_LCDCLK_DIV, BSP_CFG_LCDCLK_SOURCE);
#endif

    /* Set the USB-HS clock if it exists on the MCU */
#if BSP_FEATURE_BSP_HAS_USBHS_CLOCK && (BSP_CFG_UHSCK_SOURCE != BSP_CLOCKS_CLOCK_DISABLED)
    bsp_peripheral_clock_set(&R_SYSTEM->USBHSCKCR, &R_SYSTEM->USBHSCKDIVCR, BSP_CFG_UHSCK_DIV, BSP_CFG_UHSCK_SOURCE);
#endif

    /* Lock CGC and LPM protection registers. */
    R_SYSTEM->PRCR = (uint16_t) BSP_PRV_PRCR_LOCK;

#if BSP_FEATURE_BSP_FLASH_CACHE && BSP_FEATURE_BSP_FLASH_CACHE_DISABLE_OPM
    R_BSP_FlashCacheEnable();
#endif

#if BSP_FEATURE_BSP_FLASH_PREFETCH_BUFFER
    R_FACI_LP->PFBER = 1;
#endif
}

其中配置时钟的基地址是R_SYSTEM，定义如下：

#define R_SYSTEM         ((R_SYSTEM_Type *) R_SYSTEM_BASE)

可以查看配置时钟的结构体是R_SYSTEM_Type，该结构包含了系统时钟的所有寄存器描述，该结构体非常大，笔者只是截取了部分。

166953920468992eg0bxoz2

总结下，整个bsp_clock_init()函数的主要工作如下：

Step1：时钟配置准备阶段

解锁CGC和LPM保护
启用闪存缓存
初始化时钟参数

Step2：配置系统时钟

配置MOSC，HOCO，MOCO，PLL参数
设置源时钟和分频器

Step3：配置BCLK/SDRAM/CLKOUT输出和外设时钟

配置BCLK/SDRAM/CLKOUT
根据需求配置相应的外设时钟

Step4：锁定CGC和LPM

4 RA4M2的GPIO配置剖析

从在SystemInit ()函数中可以看到，在初始化系统的时钟前后，均调用了R_BSP_WarmStart()函数，其函数原型如下：

[文件路径: src\hal_entry.c]

/*******************************************************************************************************************//**
 * This function is called at various points during the startup process.  This implementation uses the event that is
 * called right before main() to set up the pins.
 *
 * @param[in]  event    Where at in the start up process the code is currently at
 **********************************************************************************************************************/
void R_BSP_WarmStart (bsp_warm_start_event_t event)
{
    if (BSP_WARM_START_RESET == event)
    {
#if BSP_FEATURE_FLASH_LP_VERSION != 0

        /* Enable reading from data flash. */
        R_FACI_LP->DFLCTL = 1U;

        /* Would normally have to wait tDSTOP(6us) for data flash recovery. Placing the enable here, before clock and
         * C runtime initialization, should negate the need for a delay since the initialization will typically take more than 6us. */
#endif
    }

    if (BSP_WARM_START_POST_C == event)
    {
        /* C runtime environment and system clocks are setup. */

        /* Configure pins. */
        R_IOPORT_Open(&g_ioport_ctrl, g_ioport.p_cfg);
    }
}

这里可以看到，在系统时钟初始化后，代码如下：

R_BSP_WarmStart(BSP_WARM_START_POST_CLOCK);

因此，这里就进入了GPIO的配置，核心代码如下：

R_IOPORT_Open(&g_ioport_ctrl,
g_ioport.p_cfg);

g_ioport_ctrl和g_ioport是全局变量，定义如下：

ioport_instance_ctrl_t g_ioport_ctrl;
const ioport_instance_t g_ioport =
        {
            .p_api = &g_ioport_on_ioport,
            .p_ctrl = &g_ioport_ctrl,
            .p_cfg = &g_bsp_pin_cfg,
        };

而g_ioport又内嵌了g_bsp_pin_cfg，g_bsp_pin_cfg相关的定义如下：

const ioport_pin_cfg_t g_bsp_pin_cfg_data[] = {
    {
        .pin = BSP_IO_PORT_01_PIN_08,
        .pin_cfg = ((uint32_t) IOPORT_CFG_PERIPHERAL_PIN | (uint32_t) IOPORT_PERIPHERAL_DEBUG)
    },
    {
        .pin = BSP_IO_PORT_01_PIN_09,
        .pin_cfg = ((uint32_t) IOPORT_CFG_PERIPHERAL_PIN | (uint32_t) IOPORT_PERIPHERAL_DEBUG)
    },
    {
        .pin = BSP_IO_PORT_01_PIN_10,
        .pin_cfg = ((uint32_t) IOPORT_CFG_PERIPHERAL_PIN | (uint32_t) IOPORT_PERIPHERAL_DEBUG)
    },
    {
        .pin = BSP_IO_PORT_03_PIN_00,
        .pin_cfg = ((uint32_t) IOPORT_CFG_PERIPHERAL_PIN | (uint32_t) IOPORT_PERIPHERAL_DEBUG)
    },
    {
        .pin = BSP_IO_PORT_04_PIN_04,
        .pin_cfg = ((uint32_t) IOPORT_CFG_PORT_DIRECTION_OUTPUT | (uint32_t) IOPORT_CFG_PORT_OUTPUT_LOW)
    },
    {
        .pin = BSP_IO_PORT_04_PIN_05,
        .pin_cfg = ((uint32_t) IOPORT_CFG_PORT_DIRECTION_OUTPUT | (uint32_t) IOPORT_CFG_PORT_OUTPUT_LOW)
    },
    {
        .pin = BSP_IO_PORT_04_PIN_15,
        .pin_cfg = ((uint32_t) IOPORT_CFG_PORT_DIRECTION_OUTPUT | (uint32_t) IOPORT_CFG_PORT_OUTPUT_LOW)
    },
};

const ioport_cfg_t g_bsp_pin_cfg = {
    .number_of_pins = sizeof(g_bsp_pin_cfg_data)/sizeof(ioport_pin_cfg_t),
    .p_pin_cfg_data = &g_bsp_pin_cfg_data[0],
};

从结构体数组g_bsp_pin_cfg_data中可以看到，我们芯配置的3个GPIO端口，在后面的初始时就能将其初始化了。

R_IOPORT_Open()函数的核心是r_ioport_pins_config ()。

[文件路径: ra\fsp\src\r_ioport\r_ioport.c]

/*******************************************************************************************************************//**
 * Configures pins.
 *
 * @param[in]    p_cfg          Pin configuration data
 **********************************************************************************************************************/
void r_ioport_pins_config (const ioport_cfg_t * p_cfg)
{
#if BSP_MCU_VBATT_SUPPORT
    /* Handle any VBATT domain pin configuration. */
    bsp_vbatt_init(p_cfg);
#endif

    uint16_t       pin_count;
    ioport_cfg_t * p_pin_data;

    p_pin_data = (ioport_cfg_t *) p_cfg;

    R_BSP_PinAccessEnable();           // Protect PWPR from re-entrancy

    for (pin_count = 0U; pin_count < p_pin_data->number_of_pins; pin_count++)
    {
        r_ioport_pfs_write(p_pin_data->p_pin_cfg_data[pin_count].pin, p_pin_data->p_pin_cfg_data[pin_count].pin_cfg);
    }

    R_BSP_PinAccessDisable();
}

r_ioport_pins_config ()函数中，根据GPIO的梳数量依次进行初始化。

r_ioport_pfs_write()函数的原型如下：

[文件路径: ra\fsp\src\r_ioport\r_ioport.c]

/*******************************************************************************************************************//**
 * Writes to the specified pin's PFS register
 *
 * @param[in]    pin        Pin to write PFS data for
 * @param[in]    value      Value to be written to the PFS register
 *
 **********************************************************************************************************************/
static void r_ioport_pfs_write (bsp_io_port_pin_t pin, uint32_t value)
{
    /* PMR bits should be cleared before specifying PSEL. Reference section "20.7 Notes on the PmnPFS Register Setting"
     * in the RA6M3 manual R01UH0886EJ0100. */
    if ((value & IOPORT_PRV_PERIPHERAL_FUNCTION) > 0)
    {
        /* Clear PMR */
        R_PFS->PORT[pin >> IOPORT_PRV_PORT_OFFSET].PIN[pin & BSP_IO_PRV_8BIT_MASK].PmnPFS_b.PMR = 0;

        /* New config with PMR = 0 */
        R_PFS->PORT[pin >> IOPORT_PRV_PORT_OFFSET].PIN[pin &
                                                       BSP_IO_PRV_8BIT_MASK].PmnPFS =
            (value & ~((uint32_t) IOPORT_PRV_PERIPHERAL_FUNCTION));
    }

    /* Write configuration */
    R_PFS->PORT[pin >> IOPORT_PRV_PORT_OFFSET].PIN[pin & BSP_IO_PRV_8BIT_MASK].PmnPFS = value;
}

R_PFS就是GPIO的基地址，定义如下：

#define R_PFS            ((R_PFS_Type *) R_PFS_BASE)

这里就是对GPIO 进行初始化操作，包括模式、方向等

到此，基本对时钟和GPIO分析玩了，我想大家已经对RA4M2固件库的逻辑有了一定的认识，从本质上讲，都是在配置寄存器，只是地址和值不同罢了。只是RA4M2的固件库设计比较复杂，可能对于习惯ST的风格，初学者可能会有些不适用，但是其本质是一样的。

搜索历史

【瑞萨RA4系列开发板体验】3 GPIO流水灯的前生今世

1 GPIO配置概述

2 RA4M2的时钟系统

2.1 RA4M2时钟架构

2.2 RA4M2的时钟系统

3 RA4M2的时钟配置剖析

4 RA4M2的GPIO配置剖析

相关推荐

精选推荐

最新话题

热门话题

创建小组步骤

站长推荐 /7