Yes and no.
I found it easier to use another I2S for the MCLK (@Community member wasn't that your great idea?), it's usually only setting 2 registers and the GPIO.
And you can also use the extra "I2S_CKIN" external clock as source which might not be available for the timer (unless in external clock mode, but then that's an extra input for routing).
/* SPI6 / I2S6 is in domain 3
* -> canNOT be used for DMA to non-D3 RAM
* BUT we can use it as independent
* MCLK source
*/
void I2S6_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = { 0 };
uint32_t u32I2S6Div = 0;
#if( 0 )
RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = { 0 };
/* init peripheral clock */
//PeriphClkInitStruct.Spi6ClockSelection = RCC_SPI6CLKSOURCE_PIN;
PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_SPI6;
PeriphClkInitStruct.Spi6ClockSelection = RCC_SPI6CLKSOURCE_PLL2;
if( HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK ) Error_Handler_FL(__FILE__, __LINE__);
#endif
/* I2S6 clock enable */
__HAL_RCC_SPI6_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
/* I2S6 GPIO Configuration
PA3 ------> I2S6_MCK
*/
GPIO_InitStruct.Pin = I2S6_MCLK_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF5_SPI6;
HAL_GPIO_Init(I2S6_MCLK_GPIO_Port, &GPIO_InitStruct);
/* I2S6 = SPI6 register settings
* to get MCLK output
* clock input is I2S_CKPIN, set with RCC
*/
SPI6->CR1 = 0; /* unused for I2S */
SPI6->CR2 = 0; /* unused for I2S */
/* I2SCFGR: configuration register
* most important settings here
* DMA and I2S enable are set when started
* MCKOE = 1 MCLK is ON, on/off is done with SPI_CR1_SPE
* ODD = 0 unused, for divider I2SDIV
* I2SDIV = 1 divider, start with 1 -> 25.6 MHz
* DATFMT = 0 data alignment - don't care
* WSINV = 0 LRCK hi/lo - don't care
* FIXCH = 0 data length - don't care
* CKPOL = 1 clock polarity ?
* CHLEN = 1 data length - don't care ?
* DATLEN = 10 32-bit - don't care ?
* PCMSYNC = 0 PCM short / long sync - don't care
* I2SSTD = 00 standard - don't care
* I2SCFG = 011 master RX - master is must to turn on MCLK
* I2SMOD = 1 I2S instead of SPI
*/
/* I2SCFGR: configuration register */
SPI6->I2SCFGR = I2S_CFGR_MCLK_OUT_ONLY;
/* get I2S6 MCLK frequency */
if( __HAL_RCC_GET_SPI6_SOURCE() == RCC_SPI6CLKSOURCE_PIN ) u32I2S6Mclk = RCC_VCO_CLOCK_AUDIO_200K;
else if( __HAL_RCC_GET_SPI6_SOURCE() == RCC_SPI6CLKSOURCE_PLL2 ) u32I2S6Mclk = RCC_PLL2_CLOCK_AUDIO;
else if( __HAL_RCC_GET_SPI6_SOURCE() == RCC_SPI6CLKSOURCE_PLL3 ) u32I2S6Mclk = RCC_PLL3_CLOCK_AUDIO;
else u32I2S6Mclk = 0;
u32I2S6Div = (SPI6->I2SCFGR & SPI_I2SCFGR_I2SDIV) >> SPI_I2SCFGR_I2SDIV_Pos;
if( u32I2S6Div == 0 ) u32I2S6Div = 1;
u32I2S6Mclk /= (2 * u32I2S6Div);
/* I2S6 MCLK enable - later with SAI DMA start */
#if( 1 )
/* DEBUG */
MCLK_I2S6_ON;
#endif
}
