@cyber_v1 very interesting. May I ask how you interfaced with the chip? Was it over USB or UART/JTAG? Do you have a date code? I removed the front cap of our modules and found the units that do not function were manufactured in 2023, while the working units were made in 2021. On the front of the mo...

Interesting. I used a bare ESP32-C3 chip in my design (no space for the module on the board) and ordered the PCB and assembly from JLCPCB. It worked out of the box. Even the 32kHz crystal works (initially I thought it was a hardware issue but it turned out I was dumb and it was a configuration issue).

Thanks everybody for the help!

The remaining piece of mystery is that 0x5000000&0x1ffffff=0x1000000 but as far as I understand, zero threshold was used instead, which lead to the MCU to always report the timeout. I figured this out as well. TIMG_RTC_CALI_TIMEOUT_THRES was indeed set to 0x1000000. Together with the default TIMG_R...

I have realized something while studying the ESP32-C3 Technical Reference Manual and the source code of esp-idf. I didn't reset the cranked up values between I tested the old board and the custom board :oops: :oops: :oops: I reset CONFIG_RTC_CLK_CAL_CYCLES to the default of 3000 and it worked! D (27...

Yes, the output is the same with or without the probes.

I don't understand how it's possible. It seems there is some issue with the MCU itself

The firmware doesn't detect any ticks. a) can you post the log output of the chip starting? b) what "ticks" are you looking at/for? SPIWP:0xee mode:DIO, clock div:1 load:0x3fcd5820,len:0x1708 load:0x403cc710,len:0x928 load:0x403ce710,len:0x2c4c entry 0x403cc710 I (24) boot: ESP-IDF v5.1-dirty 2nd s...

Here you are, using a 10x probe.
AFAIU pin 4 is the "input" of the crystal and pin 5 is the output. So the output is around 0.24V

The capacitors are 15pF each and the crystal is JGHC S3132768092070.
I tried to check with an oscilloscope and I see 32768 Hz oscillations, around 0.4V in amplitude. Is that not enough? The firmware doesn't detect any ticks. What am I missing?

Hello! I'm having trouble with the 32.786kHz crystal; it doesn't start! One board is Wemos C3 Pico https://www.wemos.cc/en/latest/c3/c3_pico.html; I tried two different crystals, different capacitors, tried to put a resistor in parallel (though the hardware design guidelines document says it must no...