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@neptune22222@kolektiva.social

Post #2088326

2026-04-24 19:29 UTC

@bipolaron I've just received my second revision of an ESP32-C3 prototyping board, and I've fixed an issue in my first board, which had a short circuit across the RXD and TXD pins. I've also added a CP2102N chip to connect to USB. Also, I've tried to add two buttons for pulling BOOT and RESET pins low. The buttons don't work, but I can pull the pins low manually for now. When I try to program the chip, the CP2102N shows up as a USB device in my Linux system, but it still won't program the ESP32-C3, so I'm facing a debugging problem that I haven't yet solved. I notice that the board is only drawing 10mA, and it makes me think it might not be booting up at all. When I pull EN pin low, current draw goes to 0mA, which is good. I'm wondering if the 40MHz crystal is oscillating correctly, but I'm not sure if I even have the tools to measure it. When I put my 100MHz digital oscilloscope probe against the crystal, it shows a flat line around 1V. Reading the design guidelines for the ESP32-C3, it requires an oscillation of at least 500mV, which I'm definitely not seeing on my scope. Also, when I look at the datasheet for the crystal, it doesn't show such a "minimal oscillation voltage" statistic. I can't find a recommended crystal part number anywhere, so I chose this crystal: ECS-400-10-37B2-CKY-TR I'm trying to follow these hardware design notes for the ESP32-C3 hardware: https://docs.espressif.com/projects/esp-hardware-design-guidelines/en/latest/esp32c3/schematic-checklist.html#clock-source Any ideas?

Replies (1)

  • @bipolaron@scholar.social 2026-04-24 21:48

    @neptune22222@kolektiva.social it's probably not the clock. First I'd make sure my user has permissions to /dev/ttyA whatever, though you probably know to check that. Then I'd check the power supply voltage at the chip, and that the reset pin does go high properly. Then I'd scope the digital lines from the converter chip to make sure they look reasonable, maybe the converter chip is not on. Using a scope on the crystal is unreliable, the capacitance of the tip is often enough to make them stop oscillating.

    Open ##2664098