前一段时间拿到了ST官方的STM32L4R9AI discovery开发板研究了一下。可能是刚出的板子，资料比较少，STM32cubeMX附带的例程也非常少。很多功能没有做demo，那就来慢慢给他补上吧。要达到的目标不是能跑起来就行了，要能发挥最大的性能和全部的功能。             这篇就来讲一下开发板板载的型号为IS66WV1M16EBLL的PSRAM初始化时序设置。      
     首先是MCU主频是设置在120M。

        PSRAM的FMC接口设置。

         时序设置。

       下面是寄存器设置，可以直接在SystemInit里初始化PSRAM。
__IO uint32_t tmp = 0x00;


/*-- GPIOs Configuration -----------------------------------------------------*/
   /* Enable GPIOD, GPIOE, GPIOF and GPIOG interface clock */
  RCC->AHB2ENR   |= 0x000001FF;
  /* Delay after an RCC peripheral clock enabling */
  tmp = READ_BIT(RCC->AHB2ENR, RCC_AHB2ENR_GPIODEN);

  /* Connect PDx pins to FMC Alternate function */
  GPIOD->AFR[0]  = 0xC0CC00CC;
  GPIOD->AFR[1]  = 0xCCCCCCCC;
  /* Configure PDx pins in Alternate function mode */  
  GPIOD->MODER   = 0xAAAABAFA;
  /* Configure PDx pins speed to 100 MHz */  
  GPIOD->OSPEEDR = 0xFFFFCF0F;
  /* Configure PDx pins Output type to push-pull */  
  GPIOD->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PDx pins */
  GPIOD->PUPDR   = 0x00000000;

  /* Connect PEx pins to FMC Alternate function */
  GPIOE->AFR[0]  = 0xC000C0CC;
  GPIOE->AFR[1]  = 0xCCCCCCCC;
  /* Configure PEx pins in Alternate function mode */
  GPIOE->MODER   = 0xAAAABFBA;
  /* Configure PEx pins speed to 100 MHz */
  GPIOE->OSPEEDR = 0xFFFFC0CF;
  /* Configure PEx pins Output type to push-pull */  
  GPIOE->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PEx pins */
  GPIOE->PUPDR   = 0x00000000;

  /* Connect PFx pins to FMC Alternate function */
  GPIOF->AFR[0]  = 0x00CCCCCC;
  GPIOF->AFR[1]  = 0xCCCC0000;
  /* Configure PFx pins in Alternate function mode */   
  GPIOF->MODER   = 0xAAFFFAAA;
  /* Configure PFx pins speed to 100 MHz */
  GPIOF->OSPEEDR = 0xFF000FFF;
  /* Configure PFx pins Output type to push-pull */  
  GPIOF->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PFx pins */
  GPIOF->PUPDR   = 0x00000000;

  /* Connect PGx pins to FMC Alternate function */
  GPIOG->AFR[0]  = 0x00CCCCCC;
  GPIOG->AFR[1]  = 0x00000000;
  /* Configure PGx pins in Alternate function mode */
  GPIOG->MODER   = 0xFFFFFAAA;
  /* Configure PGx pins speed to 100 MHz */
  GPIOG->OSPEEDR = 0x00000FFF;
  /* Configure PGx pins Output type to push-pull */  
  GPIOG->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PGx pins */
  GPIOG->PUPDR   = 0x00000000;

/*-- FMC/FSMC Configuration --------------------------------------------------*/
  /* Enable the FMC/FSMC interface clock */
  RCC->AHB3ENR         |= 0x00000001;


  /* Delay after an RCC peripheral clock enabling */
  tmp = READ_BIT(RCC->AHB3ENR, RCC_AHB3ENR_FMCEN);
  /* Configure and enable Bank1_SRAM1 */
  FMC_Bank1_R->BTCR[0]  = 0x00005095;
  FMC_Bank1_R->BTCR[1]  = 0x4FF104F3;
  FMC_Bank1E_R->BWTR[1] = 0x0FF103F3;


        项目代码地址在http://github.com/babycheng/STM32L4R9AIDISCOVERY.git。研究好了的代码会及时推送上去。
        项目使用 Arm Compiler 6.9 工具链，调试工具是开发板上集成的STLINK。使用MDK编译以后直接进debug模式运行。程序在SRAM1里面运行。烧进flash运行没有设置。

        本人水平有限，以上如有错误之处，敬请指出。
        转载请注明出处http://smallcsduck.blog.163.com

感谢分享，请汇总到4月技术原创
https://www.stmcu.org.cn/module/forum/thread-615497-1-1.html