Serial connection problem and connection to server failed

RIDDSprojects

Dear all,

After unpacking the M5STAMP PICO (D4), I immediately installed the latest firmware. I then soldered it directly to a PCB. However, the blue LED remains lit during startup.

The current meter on my lab power supply repeatedly jumps back and forth (approximately 50~100mA): apparently, it is repeatedly trying to connect. The Wi-Fi mode (yellow) is working properly: I can connect to configure the Wi-Fi key.

I unsoldered GPIO pins G0 through G3 to reinstall the firmware. This doesn't work. "A serial connection cannot be established."

This problem resembles https://forum.m5stack.com/topic/7606/m5stamp-pico-solid-blue-light
However, soldering seems to be the problem here
(of course, I checked for bad connections or short circuits to pins or to components near the pads).

What could I try to fix the problem? Where should I look?

Thank you in advance.

robski

@RIDDSprojects any pictures of it being soldered to pcb?

RIDDSprojects

Hi Robski,

Unfortunately, I can't show a photo due to (future) intellectual property regarding the PCB to which the module is soldered.
Thank you for your input. I'll try to explain the situation in as much detail as possible.
It was soldered manually, but professionally, and then tested for connection and short-circuiting.

When connecting the USB-TTL Downloader, external hardware was disconnected from IO pins G0, G1, and G3 by desoldering solder pads elsewhere on the PCB. EN and 3V3 are not connected.

Do you have any specific questions about the PCB?

robski

@RIDDSprojects just wonder if controller will show same issue out of your pcb

RIDDSprojects

I'm going to completely desolder the Pico and then test it separately. I suspect the problem persists because nothing has been changed on the PCB. I'll post an update of my findings here.

Perhaps it's an ESD-related issue. This is the second time a similar problem has occurred with the Pico, while it hasn't happened with other controllers in a enclosure.

bschwahn

@RIDDSprojects

Greetings,

What is the current draw of the PICO when not soldered to anything (yet doing the same tasks)? Are you sure there are not any issues with the PCB?

I am really in the dark here yet anytime soldering is involved there are concerns.

The problem might be heat related as electronic parts can be sensitive and can only survive a certain level of heat in a given amount of time. As stated ESD can also be an issue especially in dry areas where the relative humidity is less than 30 percent.

Hope you resolve your issues-Brian.

RIDDSprojects

@bschwahn
Thanks for your reply.

The current consumption fluctuates between 50 and 100mA and is due to the Wi-Fi connection (this is what all modules searching for a Wi-Fi connection or exchanging data over Wi-Fi do, so that's not surprising).

I've re-measured all the connections. I haven't desoldered the module yet.

The humidity was approximately 60%. The module was moved between different rooms after the initial firmware update, but before soldering. An ESD issue could have occurred there.

Thank you for your support.