https://esp32.com/viewtopic.php?t=14532 Consider using the RISC-V ULP processor. It's supported already, and is the obvious choice if you're writing a ULP program from scratch at this point. FSM's main use case would be for porting an existing program from ESP32, or requiring compatibility with mult...

You need to load your threshold value into a separate register. Then subtract the iterator reg and the threshold reg, result into r0.
If they are equal, r0 will be 0, so you can now use:
jumpr yourlabel 1 LT

If you don't want to pollute r0 you could subtract into any reg, then:
jump label EQ

The preferences feature is not very robust. When I define my string as char ptr and initialize it to an empty string (char * test = ""), then prefs will cause ESP32 to crash when I try to retrieve something from NVS into that char ptr. Did you try Ibernstone's solution?: "You aren't allocating any ...

Also the Tiny at 5V could well be a problem: a logic high on the I2C bus may not be high enough.
Investigate powering it from 3v3 or using level shifters.

Use the ULL (unsigned long long) modifier:
esp_deep_sleep_start(8ULL * 60 * 60 * 1000 * 1000); // sleep 8hrs

Although I can't understand why we have to "manually" call esp_phy_rf_init It needs the calibration data from somewhere. You can enable NVS so that it can store/load it as needed, you can use esp_phy_rf_init to set this data managed by your application, or you can do neither and it will need to per...

Hi Timm, I've had a tinker today to refresh my memory. Here are a few things: Please go to that first link again. I have closed the PR with a comment because I've realised that ESP-IDF already exposes a way to set phy calibration data (plus it saves the ugly mess of reserving RTC memory internally)....

Have you set CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP? https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/kconfig.html#config-bootloader-skip-validate-in-deep-sleep Also reduce bootloader logging level to none, and tie GPIO 15 low or use esp_deep_sleep_disable_rom_logging...

I think the TPS3839 should be monitoring 3V3, not VBAT.

Also you need to swap VDD/Reset.