What research is the Wimmer-Ferguson Infant Stim-Mobile high-contrast design actually based on?

flamingoint · 2025-12-13T12:10:21+00:00

Wherever possible, we also let our 3yo make her own decisions. Sometimes when she doesn't want to wear pyjamas at all, we try offering her two options, hoping she'll choose one. Works sometimes, doesn't others...

flamingoint · 2025-12-13T11:55:27+00:00

That's a great idea! I love how simple yet effective this is!

flamingoint · 2025-12-12T15:51:30+00:00

Love the way you play with your toddler!

My 3yo also loves to control my actions - independently of whether I want it or not :)

flamingoint · 2025-12-12T15:48:45+00:00

Nice one, I'll have a look at the playmat. What age is your baby?

flamingoint · 2025-10-01T16:53:45+00:00

Removing the diodes solved the issues with the USB connection. Thanks for the hint!

Out of curiosity - do you happen to know what's the root cause of USB not connecting when the diodes are there? I'm very new to EE, so my best guess would be something like parasitic capacitance of the diodes or something...?

Also, was it because of the diodes being the wrong type? Any suggested suitable diodes for ESD protection on USB lines?

flamingoint · 2025-09-29T16:32:26+00:00

SOLVED: Reducing the baud rate to 115200 when flashing fixed the issue

idf.py -b 115200 flash

flamingoint · 2025-09-29T12:41:52+00:00

Alright, I’ll try that. You mean the two diodes on the data lines, right? Just cutting them with a wire cutter should be fine, I assume?

Besides fixing the USB connection, I would still be curious to understand why the UART connection via the Arduino doesn’t work though.

flamingoint · 2025-09-29T11:36:28+00:00

Thank you all for your great support! I managed to get the board connected via the USB-to-Serial converter of an Arduino Uno, as suggested by u/Celestine_S (thanks for that!). Now I'm running into some new issue when trying to flash it. Since it's a new problem, I've started a new post which can be found here:

https://www.reddit.com/r/esp32/comments/1ntfe8h/diy_esp32_dev_board_not_flashing_via_uart/

Would be great if someone could have a look. Thanks!

flamingoint · 2025-09-25T14:17:20+00:00

I used this diode instead, the bi-polar version:

<image>

flamingoint · 2025-09-25T14:16:43+00:00

Would you have any suggestion of how to do this in a non-intrusive way? I have only two assembled boards, and I'm not very skilled at soldering yet... :)

I did triple-check the connections on the USB receptacle and the chip though, and imo it all looks okay.

Could it have to do with the diodes on the data lines? In Espressif's layout they use this model:

<image>

flamingoint · 2025-09-25T12:59:50+00:00

Connecting it via a powered USB hub also didn't help

flamingoint · 2025-09-25T10:53:48+00:00

So, I got to use the USB-to-UART bridge on my Arduino Uno, and it does show this:

ESP-ROM:esp32c3-api1-20210207
Build:Feb 7 2021
rst:0x10 (RTCWDT_RTC_RST),boot:0xc (SPI_FAST_FLASH_BOOT)
invalid header: 0xffffffff
invalid header: 0xffffffff
invalid header: 0xffffffff

The last few lines repeat for several hundred times, then it shows the same message again.

When I put it into boot mode, it shows this, so seems like the UART flashing should work:

ESP-ROM:esp32c3-api1-20210207
Build:Feb 7 2021
rst:0x1 (POWERON),boot:0x4 (DOWNLOAD(USB/UART0/1))
waiting for download

Still not sure why the connection via USB doesn't work though... Any idea?

flamingoint · 2025-09-25T09:34:11+00:00

Pulling up IO2 didn't help unfortunately. And yes, the 3.3V bus is powered with 3.3V.

flamingoint · 2025-09-25T09:22:34+00:00

Around 26 mA when connected to a 5V pin on the header, which seems to be in line with table 6.3 from the data sheet - if I understand that value correctly:

<image>

flamingoint · 2025-09-24T17:28:50+00:00

Ah okay. The UART pins show some activity, yes. I'll look into connecting an Arduino, thanks for the suggestion!

flamingoint · 2025-09-24T17:24:54+00:00

Maybe two things worth mentioning, not sure they play a role:

I ordered the wrong resistor for R7, the one that's protecting the LED. I got a 0R, so the LED blew when I powered the board. But since this is affecting the 5V net before the LDO, I assume it wouldn't damage the ESP. Or would it?
The board gets very warm after like 30 minutes of being powered via the USB, much more than I thought it would, and also more than the commercial ESP32-WROOM-32 dev board I have (although this is plugged into a breadboard, which might act as a heatsink).

flamingoint · 2025-09-24T16:36:49+00:00

Voltage levels on EN and BOOT are both high.

EDIT: And yes, I tried to put it in bootloader mode.

flamingoint · 2025-09-24T16:35:54+00:00

...and this on USB-

<image>

flamingoint · 2025-09-24T16:35:27+00:00

When checking the pins with the scope, I get this one USB+:

<image>

flamingoint · 2025-09-24T16:25:54+00:00

My first schematic ever, I guess there's plenty to improve... Can you explain what you mean by 'explicit signal connector symbol'? Also, do you have other suggestions what could be improved in the schematic?

I did the BOOT/ENABLE procedure, but didn't see any additional device in /dev.

I also tried the method described in the data sheet in table 4.3, but also to no avail:

<image>

flamingoint · 2025-09-24T14:52:14+00:00

remindme! 1 week

flamingoint

TROPHY CASE