ESP8266 rare hang

Hi again,

well, I have been trying with the lates ESP8266 1.3.0 SDK but the problem still persists. Sometimes, when the WIFI connection is lost (switching off the router for example), and the WIFI network comes back, the ESP8266 module does not recover, and from that moment on, it will NEVER recover. A network scan does not show the network. And even if you reset the system, the ESP8266 does not recover.

However, if you ERASE the full flash and you flash your program again with esptool.py, the system recovers.

The reason is that the internal firmware stores something in the flash that is not correct, and the system cannot recover from that situation without cleaning the sector where this wrong information has been written.

We have done an experiment. We place this at the begining of the user_main function (after UART initialization):

 

uint16_t s,res;

os_printf(“Erasing sectors\n”);
for (s=0x70;s<=0x7F; s++)
{
res = spi_flash_erase_sector(s);
os_printf(“Sector erased 0x%02X. Res %d\n”,s,res);
}

And when the system hangs, it recovers after reset always!!!

Now, we inspect:

python esptool.py erase_flash

python esptool.py read_flash 0x00000 0x80000 erased.bin

python esptool.py write_flash 0x00000 firmware\0x00000.bin 0x40000 firmware\0x40000.bin

python esptool.py read_flash 0x00000 0x80000 written.bin

then we corrupt the system by switching on and off the wifi, and we read back the result:

python esptool.py read_flash 0x00000 0x80000 corrupted.bin

And wow!! It is there! We have changes in 0x7D000 0x7E000 and 0x7F000

0x7D000

0x7E000

0x7F000

This is not a real surprise:

config ADDR_BLOBSETTING1
hex "Adress of blob settings in flash (copy 1)"
default 0x7d000

config ADDR_BLOBSETTING2
hex "Adress of blob settings in flash (copy 2)"
default 0x7e000

But 0x7F000 ???? What is this doing there??