Pico D4 unable to flash

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SimoneT
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Joined: Mon Jun 27, 2022 11:51 am

Pico D4 unable to flash

Postby SimoneT » Mon Jun 27, 2022 12:04 pm

Hi folks, I'm developing a custom Pico D4 board which has been prototyped.
Problem is that there is no communication with Pico, the CP2104 becomes visible but it is impossible to flash it:

Connecting........_____....._____....._____....._____....._____....._____....._____
A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header
*** [upload] Error 2

Same result from PlatformIO or using esptool.py manually...

Things I tryed:
- Swapping 10uF capacitor on RST with a 1uF
- Removing pullup on GPIO0
- Manually trying to pull GPIO0 low while resetting
- Even removing the Pico to check that there are no solder bridges underneath

I know from the datasheet that GPIO2 and GPIO12 may be left floating since they have internal pullups/down
I cutted the jumper to leave GPIO16 unconnected.
Still no luck

Powering the board with 5V it is drawing +/-30mA which seems to be a little on the low side.

Would you mind having a look at my schematics and provide me with some feedback?

Thanks a lot!
Attachments
ESP32miniCAN SCH.pdf
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ESP_Sprite
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Joined: Thu Nov 26, 2015 4:08 am

Re: Pico D4 unable to flash

Postby ESP_Sprite » Tue Jun 28, 2022 7:17 am

- Are you getting a proper 3.3V?
- If you open a terminal (or idf.py monitor) and you reset the ESP, do you get any chatter on the serial port?

EDIT: Think I found it: Your VDD3P3_RTC is not connected to 3.3V.

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SimoneT
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Joined: Mon Jun 27, 2022 11:51 am

Re: Pico D4 unable to flash

Postby SimoneT » Tue Jun 28, 2022 7:21 am

Hi,
- yes 3.3V stable
- no feedback in a terminal when resetting the board

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SimoneT
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Re: Pico D4 unable to flash

Postby SimoneT » Tue Jun 28, 2022 7:26 am

I see thanks.
Do you think that not powering RTC may make the Pico unable to work properly?

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SimoneT
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Re: Pico D4 unable to flash

Postby SimoneT » Tue Jun 28, 2022 12:27 pm

I tryied soldering a very thin wire from the unconnected pin to 3,3V but it doesn't change.
Admittedly soldering a qfn pin to a wire is not that easy, under the microscope it seems ok but I may have made a bad joint...

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