Reason and cause for RTCWDT_RTC_RESET on boot?

[desp32fun]

Hi all,
what is the intended reason and cause for RTCWDT_RTC_RESET on boot?
I had some WROVER-E Modules dying in the field with an RTCWDT_RTC_RESET boot loop after weeks of proper operation.
Sadly, the module does not recover by re-flashing the module like in the first thread below.
My hope would be something buried in the bootloader which could be fixed or circumvented in software?

RTCWDT_RTC_RESET pops up in this thread about WROVER-E: "Hardware Flash Corruption Issue"
https://www.esp32.com/viewtopic.php?f=12&t=25667#p90766

RTCWDT_RTC_RESET pops up in a thread with a different flash-chip: "ESP32-D0WD Design Issue."
viewtopic.php?f=2&t=22813

and probably more. Sadly, the forum search as always only returns an empty white page, so I can't search properly
for more hints.

What I see:

Code: Select all

ets Jul 29 2019 12:21:46

rst:0x10 (RTCWDT_RTC_RESET),boot:0x33 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:2
load:0x3fff0030,len:380
ho 0 tail 12 room 4
load:0x0780000,len:3378177
ets Jul 29 2019 12:21:46

rst:0x10 (RTCWDT_RTC_RESET),boot:0x33 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:2
load:0x3fff0030,len:380
load:0x07800000,len:3378177
ets Jul 29 2019 12:21:46

rst:0x10 (RTCWDT_RTC_RESET),boot:0x33 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:2
load:0x3fff0030,len:380
ho 0 tail 12 room 4
load:0x07800000,len:3378177
ets Jul 29 2019 12:21:46

Any hints there?
Best regards

[WiFive]

Similar to those other issues, there is a problem loading the second stage bootloader from flash. boot:0x33 shows 1.8v flash mode which is not correct for wrover-e unless you override it in efuse.

viewtopic.php?f=12&t=22938

[desp32fun]

I see. Now there's a problem. I've pinned SDIO voltage to 3V3 by burning the appropriate fuse,
and as it seems, the bootloader does not pick that setting up, setting the flash to 1V8?

Are we talking about these fuses?

Code: Select all

espefuse.py --port /dev/ttyUSB0 summary

XPD_SDIO_FORCE (BLOCK0):                 Ignore MTDI pin (GPIO12) for VDD_SDIO on reset     = True R/W (0b1)
XPD_SDIO_REG (BLOCK0):                   If XPD_SDIO_FORCE, enable VDD_SDIO reg on reset    = True R/W (0b1)
XPD_SDIO_TIEH (BLOCK0):                  If XPD_SDIO_FORCE & XPD_SDIO_REG                   = 3.3V R/W (0b1)
... lots of stuff ...
Flash voltage (VDD_SDIO) set to 3.3V by efuse.

[WiFive]

You will not see a change to the boot:0x33 value because it represents strapping pins only

[desp32fun]

So do I understand this correctly?

When some of our WROVER-E boards boot, they provide the flash with 1.8V instead of 3.3V?
And they show in the boot loader that GPIO12 is reading HIGH on startup? (boot:0x33)
And this happens although we've set the Fuses that force VDD_SDIO to 3.3V?

[WiFive]

No, if you set the efuse to force 3.3v you should get 3.3v even with gpio12 high. So that is not the problem then.