Question
STM32H747I-DISCO — HardFault_Handler intermittently triggered during Ethernet + LwIP, ping never succeeds
Hi all,
I'm working on the STM32H747I-DISCO (CM7 core, bare-metal LwIP without RTOS, polling mode via MX_LWIP_Process()). Goal is simply to get the board to respond to ping from my PC over Ethernet.
Hardware done:
- Solder bridge rework completed per UM2411 Table 5: SB8 closed / SB21 open (PC1 → ETH_MDC instead of mic DOUT), R87 open / SB17 closed (PE2 → ETH_nINT instead of mic CLK)
Software config:
- ETH set to RMII mode in CubeMX, all 9 RMII pins showing green in Pinout view (PA1, PA2, PA7, PC1, PC4, PC5, PG11, PG12, PG13)
- LWIP middleware enabled, static IP configured (matching my PC's subnet), no DHCP
- USART3 used for debug output via Putty
- Everything runs on CM7 only; CM4 isn't touching ETH/LWIP
Symptom:
The code intermittently jumps into HardFault_Handler(void) — not on every run, which points to a timing/cache-related issue rather than a hard config error. When it doesn't crash, ping still doesn't get a reply.
/* USER CODE BEGIN 0 */
extern struct netif gnetif;
/* USER CODE END 0 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
ethernetif_input(&gnetif);
sys_check_timeouts();
}
