Posted on August 08, 2013 at 21:17I faced a critical problem of i2s of STM32.
I'm developing a simple system for i2s level meter.
MCU - STM32F103RCT6 with external X-tal(12MHz), 72MHz of running clock
Inpit Audio - 48KHz, 16bits, stereo i2s digital audio (MCU pin : WS, SD, SCK used)
Using the ST library,
First, I set RCC like this,
SystemInit (); // set system clock - 72MHz
...
RCC_APB1PeriphClockCmd( RCC_APB1Periph_I2C1 | RCC_APB1Periph_SPI2, ENABLE ); // I2S
...
then, I set I2Ss port,NVIC_InitTypeDef NVIC_InitStructure;
/* SPI2 IRQ channel configuration */
NVIC_InitStructure.NVIC_IRQChannel = SPI2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x00;
NVIC_Init(&NVIC_InitStructure);
SPI_I2S_DeInit(SPI2);
/* I2S peripheral configuration */
I2S_InitStructure.I2S_Standard = I2S_Standard_Phillips;
I2S_InitStructure.I2S_DataFormat = I2S_DataFormat_16bextended;
I2S_InitStructure.I2S_MCLKOutput = I2S_MCLKOutput_Disable;
I2S_InitStructure.I2S_AudioFreq = I2S_AudioFreq_48k;
I2S_InitStructure.I2S_CPOL = I2S_CPOL_Low;
/* I2S2 configuration */
I2S_InitStructure.I2S_Mode = I2S_Mode_SlaveRx;
I2S_Init(SPI2, &I2S_InitStructure);
/* Enable the I2S2 */
I2S_Cmd(SPI2, ENABLE);
/* Enable the I2S2 RxNE interrupt */
SPI_I2S_ITConfig(SPI2, SPI_I2S_IT_RXNE, ENABLE);
After that,
I read i2s register, when i2s audio of simple tone signal was connected,
the maximum value was changed intermittently.
10 results of test are below
test 0 : 3592
test 1 : 3592
test 2 : 3592test 3 : 0
test 4 : 3592test 5 : 32177
test 6 : 4095
test 7 : 32177
test 8 : 63
test 9 : 3592( expected value of I2S is 3592)
I guess this problem is about init i2s port or clock,so I did almost change options.
(changed Dataformat, Mode, CPOL, AudioFreq...)
but it was not effective.
Would you help me if you have an experience of i2s?
Thanks for all,
Frank
#slave #stm32 #i2s
