Posted on November 09, 2015 at 17:11
Ok, so this is my third wave to get into STM32F7, since i have project where tons of complex math needs to be executed in very short time, so i must use STM32F7.
As long as i go as far away from DMA as i can, i guess i can make it work.
But reading article about STM32F7 i found interesting information:
/* Buffers use fro DMA access must begin on an address aligned with the
* D-Cache line and must be an even multiple of the D-Cache line size.
* These size/alignment requirements are necessary so that D-Cache flush
* and invalidate operations will not have any additional effects.
*
* The TX and RX descriptors are normally 16 bytes in size but could be
* 32 bytes in size if the enhanced descriptor format is used (it is not).
*/
/* DMA buffers. DMA buffers must:
*
* 1. Be a multiple of the D-Cache line size. This requirement is assured
* by the definition of RXDMA buffer size above.
* 2. Be aligned a D-Cache line boundaries, and
* 3. Be positioned in DMA-able memory (*NOT* DTCM memory). This must
* be managed by logic in the linker script file.
*
* These DMA buffers are defined sequentially here to best assure optimal
* packing of the buffers.
*/
/* Descriptor allocations */
static union stm32_rxdesc_u g_rxtable[RXTABLE_SIZE]
__attribute__((aligned(ARMV7M_DCACHE_LINESIZE)));
static union stm32_txdesc_u g_txtable[TXTABLE_SIZE]
__attribute__((aligned(ARMV7M_DCACHE_LINESIZE)));
/* Buffer allocations */
static uint8_t g_rxbuffer[RXBUFFER_ALLOC]
__attribute__((aligned(ARMV7M_DCACHE_LINESIZE)));
static uint8_t g_txbuffer[TXBUFFER_ALLOC]
__attribute__((aligned(ARMV7M_DCACHE_LINESIZE)));
So maybe thats why i get data, but data was corrupted. who knows
