Posted on July 22, 2013 at 18:28
Hi all!
I'm new in forum.
I wrote this config for I2S.
Instead of MCLK=256*Fs=12, 288000 MHz and CK=48KHz*32bit*2channel=3, 072000 MHz, I measured MCLK=4MHz and CK=1 MHz.
My code is:
RCC_APB1PeriphClockCmd (RCC_APB1Periph_SPI2, ENABLE);
// ....................
/* Connect pins to I2S peripheral */
GPIO_PinAFConfig (PCM1804_PORTC, PCM1804_SCKI_PS, GPIO_AF_SPI2); // I2S2_SCKI
GPIO_PinAFConfig (PCM1804_PORTB, PCM1804_I2S2_CK_PS, GPIO_AF_SPI2); // I2S2_CK
GPIO_PinAFConfig (PCM1804_PORTB, PCM1804_I2S2_SD_PS, GPIO_AF_SPI2); // I2S2_SD
GPIO_PinAFConfig (PCM1804_PORTB, PCM1804_I2S2_LRCK_PS, GPIO_AF_SPI2); // I2S2_LRCK , WS
// I2S2 peripheral configuration
I2S_InitTypeDef I2S2_InitStructure;
SPI_I2S_DeInit (SPI2);
/* For this standard, the WS signal is used to indicate which channel is being transmitted. It is
activated one CK clock cycle before the first bit (MSB) is available.
*/
I2S2_InitStructure.I2S_Standard = I2S_Standard_Phillips;
I2S2_InitStructure.I2S_DataFormat = I2S_DataFormat_24b;
I2S2_InitStructure.I2S_MCLKOutput = I2S_MCLKOutput_Enable;
I2S2_InitStructure.I2S_AudioFreq = I2S_AudioFreq_48k; //
I2S2_InitStructure.I2S_CPOL = I2S_CPOL_Low; //
I2S2_InitStructure.I2S_Mode = I2S_Mode_MasterRx; //
I2S_Init (SPI2, &I2S2_InitStructure);
/* I2S_INTERRUPT */
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_InitStructure.NVIC_IRQChannel = SPI2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init (&NVIC_InitStructure);
/* Enable the Rx buffer not empty interrupt */
SPI_I2S_ITConfig (SPI2, SPI_I2S_IT_RXNE, ENABLE); //
I2S clock configuration in system file is:
/************************* PLL Parameters *************************************/
/* PLL_VCO = (HSE_VALUE or HSI_VALUE / PLL_M) * PLL_N */
#define PLL_M (uint32_t)8
#define PLL_N (uint32_t)336
/* SYSCLK = PLL_VCO / PLL_P */
#define PLL_P (uint32_t)2
/* USB OTG FS, SDIO and RNG Clock = PLL_VCO / PLLQ */
#define PLL_Q (uint32_t)7
/* PLLI2S_VCO = (HSE_VALUE Or HSI_VALUE / PLL_M) * PLLI2S_N
I2SCLK = PLLI2S_VCO / PLLI2S_R */
#define PLLI2S_N (uint32_t)258
#define PLLI2S_R (uint32_t)3
//.................
/******************************************************************************/
/* I2S clock configuration */
/******************************************************************************/
/* PLLI2S clock used as I2S clock source */
RCC->CFGR &= ~RCC_CFGR_I2SSRC;
/* Configure PLLI2S */
RCC->PLLI2SCFGR = (PLLI2S_N << 6) | (PLLI2S_R << 28);
/* Enable PLLI2S */
RCC->CR |= ((uint32_t)RCC_CR_PLLI2SON);
/* Wait till PLLI2S is ready */
while((RCC->CR & RCC_CR_PLLI2SRDY) == 0)
{
}
On disvovery board the oscillator frequency is 8MHz, and in stm32f4xx.h the HSE value is:
#if !defined (HSE_VALUE)
#define HSE_VALUE ((uint32_t)8000000) /*!< Value of the External oscillator in Hz */
#endif /* HSE_VALUE */
Thank you !
Regards
uprog
#stm32f4-i2s
