That was the same issue that was reported in post startup-freertos-9-0-0-stm32f4-interrupt-before-starting-scheduler-hang/7105
Mentioned post appeared first on Sourceforge, but there is a copy here
I have also tried not defining them and allowing the driver to use its default values which are 5 and 5.
Note that you can safely set ETH_TXBUFNB to 1, and ETH_RXBUFNB to many, 9 if you have. When sending, the driver will wait patiently for a free DMA buffer. That happens in this line:
if( xSemaphoreTake( xTXDescriptorSemaphore, xBlockTimeTicks ) != pdPASS )
{
/* Time-out waiting for a free TX descriptor. */
break;
}
It will wait for at most 50 ms, which gives enough time for the previous packet to be transmitted.
So I recommend:
#define ETH_RXBUFNB 9
#define ETH_TXBUFNB 1
Note that each RX DMA buffer needs one Network Buffer. When there is no buffer available, an incoming packet will be dropped, in prvNetworkInterfaceInput.
About versions, have you tried the latest version of FreeRTOS+TCP?
And a last thought: I still wonder if there is a slight difference between the EMACs of an STM32F2 and STM32F4.