[嵌入式]S32K之时钟模块及串口通信

概述

S32K系列芯片开发时，尽管官方提供了SDK并且目前已经更新至4.02版本，并有Processor expert一键配置，时钟，外设，中断等等组件经过配置之后，可以生成驱动函数，一键拖动调用，一部分需要手动填充入参。即使这样在开发过程中不明所以，新项目也仅仅是参考移植，没有增长。所以打算对每个外设做一个手写版本，并作记录。

时钟

S32K的时钟比较多，FIRC,SIRC,SOSC,LPO,RTC。在S32K1XXX系列中没有PLL，通过配置使能相关寄存器，达到想要的时钟源及时钟分频，但看参考手册不够直观，S32DS提供了明了的始终结构，对开发很有帮助
上图为运行状态下的时钟图

上图为外设的时钟选择


以上是VCCR的时钟分配

参考以上时钟图可以很清楚的知道需要配置哪些寄存器，始终结构是怎样的组成，但是一旦时钟配置有误，会出现不能驱动外设的情况，具体在debug模式下可以查看该时钟寄存器的VLD状态，如果配置没有问题，该位置位。我在驱动串口时，发现发送缓冲区一直处于full状态，查了好久才发现SOSCVLD位没有置位，在修改串口时钟源为SIRC之后，可以发送数据。

时钟初始化代码

#include "clockdriver.h"
static void ConfigFIRC(void)
{
	SCG->FIRCCSR &= (uint32_t)(~SCG_FIRCCSR_FIRCEN_MASK);
	SCG->FIRCDIV = SCG_FIRCDIV_FIRCDIV1(1) | SCG_FIRCDIV_FIRCDIV2(1);
	SCG->FIRCCFG = SCG_FIRCCFG_RANGE(0);
	while(SCG->FIRCCSR & SCG_FIRCCSR_LK_MASK);
	SCG->FIRCCSR = SCG_FIRCCSR_FIRCEN(1);
	while((SCG->FIRCCSR & SCG_FIRCCSR_FIRCVLD_MASK) >> SCG_FIRCCSR_FIRCVLD_SHIFT != 1);
}
static void ConfigSIRC(void)
{
	SCG->SIRCCSR &= (uint32_t)(~SCG_SIRCCSR_SIRCEN_MASK);
	SCG->SIRCDIV = SCG_SIRCDIV_SIRCDIV1(1) | SCG_SIRCDIV_SIRCDIV2(1);
	SCG->SIRCCFG = SCG_SIRCCFG_RANGE(1);
	while(SCG->SIRCCSR & SCG_SIRCCSR_LK_MASK);
	SCG->SIRCCSR = SCG_SIRCCSR_SIRCEN(1);
	while((SCG->SIRCCSR & SCG_SIRCCSR_SIRCVLD_MASK) >> SCG_SIRCCSR_SIRCVLD_SHIFT != 1);
}
static void ConfigSOSC(void)
{
	SCG->SOSCDIV = SCG_SOSCDIV_SOSCDIV1(1) | SCG_SOSCDIV_SOSCDIV2(1);
	SCG->SOSCCFG = SCG_SOSCCFG_RANGE(2) | SCG_SOSCCFG_HGO(0) | SCG_SOSCCFG_EREFS(1);
	while(SCG->SOSCCSR & SCG_SOSCCSR_LK_MASK);
	SCG->SOSCCSR = SCG_SOSCCSR_SOSCEN(1);
	while((SCG->SOSCCSR & SCG_SOSCCSR_SOSCVLD_MASK) >> SCG_SOSCCSR_SOSCVLD_SHIFT != 1);
}
static void ConfigLPO(void)
{
	SIM->LPOCLKS = SIM_LPOCLKS_LPO32KCLKEN(1);
	SIM->LPOCLKS = SIM_LPOCLKS_LPO32KCLKEN(1);
	SIM->LPOCLKS = SIM_LPOCLKS_LPOCLKSEL(0);
	SIM->LPOCLKS = SIM_LPOCLKS_RTCCLKSEL(3);
 }
static void ConfigRunMode(void)
{
    SCG->RCCR = SCG_RCCR_SCS(3) | SCG_RCCR_DIVCORE(0) | SCG_RCCR_DIVSLOW(1) | SCG_RCCR_DIVBUS(0);
    while((SCG->CSR & SCG_CSR_SCS_MASK) != (uint32_t)0x03000000);
}
static void ConfigVLPRMode(void)
{
	SCG->VCCR = SCG_VCCR_SCS(2) | SCG_VCCR_DIVCORE(1) | SCG_VCCR_DIVBUS(0) | SCG_VCCR_DIVSLOW(3);
}

void ConfigClkOut(void)
{
	SCG->CLKOUTCNFG |= SCG_CLKOUTCNFG_CLKOUTSEL(1);
	SIM->CHIPCTL &= ~SIM_CHIPCTL_CLKOUTEN_MASK;
	SIM->CHIPCTL &= ~SIM_CHIPCTL_CLKOUTSEL_MASK;
	SIM->CHIPCTL |= SIM_CHIPCTL_CLKOUTSEL(2);
	SIM->CHIPCTL |= SIM_CHIPCTL_CLKOUTDIV(0);
	SIM->CHIPCTL |= SIM_CHIPCTL_CLKOUTEN(1);
}

void ClockInit(void)
{
	(void)ConfigFIRC();
	(void)ConfigSIRC();
	(void)ConfigSOSC();
	//(void)ConfigLPO();
	(void)ConfigRunMode();
	//(void)ConfigVLPRMode();
}

串口代码只写了发送，使能了FIFO,未使用中断

void Uart0Init(void)
{
	PCC->PCCn[PCC_PORTC_INDEX] |= PCC_PCCn_CGC(1);
/* SET PIN PTC2 MUX AS UART0_TX, SET PIN PTC3 MUX AS UART0_RX*/
	PORTC->PCR[2] &=PORT_PCR_MUX_MASK;
	PORTC->PCR[2] |= PORT_PCR_MUX(4);//PTC2 MUX = ALT4, UART0_TX
	PORTC->PCR[3] &=PORT_PCR_MUX_MASK;
	PORTC->PCR[3] |= PORT_PCR_MUX(4);//PTC3 MUX = ALT4, UART0_RX
/* SET PIN MUX END */
/*
 * TURN OFF CLOCK BEFORE SELECT CLOCK
 * */
	PCC->PCCn[PCC_LPUART0_INDEX] &= ~PCC_PCCn_CGC_MASK;
	PCC->PCCn[PCC_LPUART0_INDEX] &= ~PCC_PCCn_PCS_MASK;
/* SELECT CLOCK SOURCE UART0 */
	PCC->PCCn[PCC_LPUART0_INDEX] |= PCC_PCCn_PCS(1);
/* SELECT CLOCK SOURCE UART0 END */
/* ENABLE CLOCK TO UART0 */
	PCC->PCCn[PCC_LPUART0_INDEX] |= PCC_PCCn_CGC(1);
/* ENABLE CLOCK TO UART0 END */
	LPUART0->CTRL &= ~LPUART_CTRL_TE_MASK;
	LPUART0->CTRL &= ~LPUART_CTRL_RE_MASK;
	LPUART0->BAUD |=  LPUART_BAUD_SBR(52);
	LPUART0->BAUD |=  LPUART_BAUD_OSR(15);
	LPUART0->CTRL |= LPUART_CTRL_TE_MASK;
	LPUART0->CTRL |= LPUART_CTRL_RE_MASK;

	LPUART0->FIFO = 0x0003C000;
	LPUART0->FIFO |= LPUART_FIFO_TXFE_MASK;
	LPUART0->FIFO |= LPUART_FIFO_RXFE_MASK;
	LPUART0->WATER = 0x00000000;
	LPUART0->WATER |= LPUART_WATER_TXWATER(3);
	LPUART0->WATER |= LPUART_WATER_RXWATER(3);


	while((LPUART0->CTRL & LPUART_CTRL_TE_MASK) != LPUART_CTRL_TE_MASK);

}

uint8_t UartSendChar(uint8_t buff)
{
	int count = 0;
	while(((LPUART0->STAT & LPUART_STAT_TDRE_MASK) != LPUART_STAT_TDRE_MASK) && count++ < 0xFFFF);
	if(count >= 0xFFFF)
		return 0;
	LPUART0->DATA = buff;
	return 1;
}

uint8_t UartSendString(uint8_t *buff,uint8_t len)
{
	uint8_t i;
	for(i = 0;i<len;i++)
	{
		if(!UartSendChar(buff[i]))
			break;
	}
	if(i < len)
		return 0;
	else
		return 1;

}

主函数如下

/* ###################################################################
**     Filename    : main.c
**     Processor   : S32K1xx
**     Abstract    :
**         Main module.
**         This module contains user's application code.
**     Settings    :
**     Contents    :
**         No public methods
**
** ###################################################################*/
/*!
** @file main.c
** @version 01.00
** @brief
**         Main module.
**         This module contains user's application code.
*/         
/*!
**  @addtogroup main_module main module documentation
**  @{
*/         
/* MODULE main */


/* Including necessary module. Cpu.h contains other modules needed for compiling.*/
#include "Cpu.h"
#include "include.h"

uint8_t Buff2Send[3] = {0x55,0xAA,0xCC};
volatile uint32_t clocktick =  0;
volatile int exit_code = 0;

#define MAXVALUE 50000
/* User includes (#include below this line is not maintained by Processor Expert) */

/*! 
  \brief The main function for the project.
  \details The startup initialization sequence is the following:
 * - startup asm routine
 * - main()
*/
int main(void)
{
  /* Write your local variable definition here */

  /*** Processor Expert internal initialization. DON'T REMOVE THIS CODE!!! ***/
  #ifdef PEX_RTOS_INIT
    PEX_RTOS_INIT();                   /* Initialization of the selected RTOS. Macro is defined by the RTOS component. */
  #endif
  /*** End of Processor Expert internal initialization.                    ***/

  /* Write your code here */
  /* For example: for(;;) { } */
    wdog_stop();
    ClockInit();
    Uart0Init();
    for(;;)
    {
    	clocktick++;
    	if(clocktick > MAXVALUE)
    	{
    		UartSendString(Buff2Send,3);
    		clocktick = 0;
    	}
    }

  /*** Don't write any code pass this line, or it will be deleted during code generation. ***/
  /*** RTOS startup code. Macro PEX_RTOS_START is defined by the RTOS component. DON'T MODIFY THIS CODE!!! ***/
  #ifdef PEX_RTOS_START
    PEX_RTOS_START();                  /* Startup of the selected RTOS. Macro is defined by the RTOS component. */
  #endif
  /*** End of RTOS startup code.  ***/
  /*** Processor Expert end of main routine. DON'T MODIFY THIS CODE!!! ***/
  for(;;) {
    if(exit_code != 0) {
      break;
    }
  }
  return exit_code;
  /*** Processor Expert end of main routine. DON'T WRITE CODE BELOW!!! ***/
} /*** End of main routine. DO NOT MODIFY THIS TEXT!!! ***/

/* END main */
/*!
** @}
*/
/*
** ###################################################################
**
**     This file was created by Processor Expert 10.1 [05.21]
**     for the NXP S32K series of microcontrollers.
**
** ###################################################################
*/

利用示波器或者逻辑分析仪可以验证波特率和发送数据是否正常。
看门狗在缺省状态下为开启，所以第一步需要禁用，这也是一个坑