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STM32F756 Ethernet needs DTCM

Question asked by diz on Nov 22, 2017
Latest reply on Dec 4, 2017 by diz


I have problems with ethernet (using the HAL library 1.8.0) on the STM32F756ZG.

If I place the DMA buffers in the DTCM (0x20000000-0x2000ffff), it works fine. If I place the DMA buffer anywhere else (SRAM1, SRAM2), I get only on every second ping an answer (50% loss).

I don't use the MPU and I don't activate the data cache (SCB.CCR.DC = 0).

I also tried (despite the dcache being deactivated) flushing the data cache (SCB_DCacheClean()) before sending data in low_level_output() and invalidating the data cache (SCB_DCacheInvalidate()) before reading data in low_level_input(), but to no avail.

Does anybody has an idea?