RP2040-Zero + SN74AHCT125N

[AstaRom]

Good day @awawa-dev

I decided to try the rp2040 board in my assembly (the main board at the moment is esp32).
I sketched out the circuit, soldered everything, and launched it for testing.

With the following connection diagram everything worked fine:

• the board 'rp2040' was powered via Type-C;
• the 'level shifter' received power from the 'LED strip';
• Common ground line between 'SN74AHCT125N', 'LED strip', 'rp2040' board and 'RPi4'.

The rp2040 specification states that the board can be powered directly through pins on the board (5V, GND), rather than just via USB.
I decided to try it out and powered the board directly from the LED strip unit, similar to a level shifter.

• the board 'rp2040' received power from the 'LED strip';
• the 'level shifter' received power from the 'LED strip';
• Common ground line between 'SN74AHCT125N', 'LED strip', 'rp2040' board and 'RPi4'.

Connection diagram

With this scheme, everything stops working, 3 to 4 diodes in the strip periodically blink.
The 'rp2040' board does not respond in any way to commands from the HyperHDR interface.

Have you by any chance tried this type of connection?
If so, did everything work fine?

[awawa-dev]

Hi
Sorry, I've no clue :( I don't use power by pinout solution because I dont trust such connections but it's my experience from Raspberry Pi SBC boards not Pico. As far I know 5v pin on Zero board is VSYS so you can power the board using external power supply when the USB-C is disconnected (https://www.penguintutor.com/electronics/pico-power). Unless they connected it to VBUS directly during the cost "optimization" process and then the LED power supply may be out of the tolerance.

3 to 4 diodes in the strip periodically blink.

if these LEDs blink even when HyperHDR is not working that's the mayor problem. Something triggers data line and it's not HyperSPI because it's using data integrity check. Maybe it's a common ground problem somehow (loops)?

[AstaRom]

If you have a spare usb2.0 cable you can do an experiment and after removing the cable plug and accessing the individual wires connect the 5v cable to the 5v pin and the ground from that cable to the board. Then provide a power supply (ex. from the power bank). If this works, the problem lies in the unstable power supply. Maybe a decoupling capacitor will help a bit? Unfortunately, I'm not an electronics engineer ;)

Today I received a new board. I installed it and everything worked fine.
The RP2040 receives power through the contacts (5V, GND) on the board and HyperHDR can now control it normally.

It turns out that I received the first board with a manufacturing defect/malfunction.

[awawa-dev]

Did you receive exactly the same model?

[AstaRom]

Did you receive exactly the same model?

Yes, exactly the same board, in appearance. The only difference is that I bought it from a different seller.

[awawa-dev]

Strange. Although I've heard of problems with some Pico Zeros powered directly but by 3.3V (installed for nefarious purposes in certain consoles). So maybe their quality matters in certain scenarios.

[AstaRom]

Perhaps, in the first board purchased, some element (resistor, capacitor, etc.) was not soldered on it or was poorly soldered. With conveyor assembly, no one is immune from this. I quickly examined both, it seems that everything that is on the first one is also on the second one, but whether they are welded well or not, most likely, can only be seen through a microscope.

[AstaRom]

While I had a free minute, I made a sketch of the printed circuit board.

Example

It's easier to put together than the example in the title of the discussion, but it's less compact.

I think these examples may be useful to users of the HyperHDR community.

[TechsavvyCNC]

So you only have to connect 5 volts to the one pin on the SN74AHCT125N?

[AstaRom]

Top block, top to bottom: +5, Led data 1, Led data 2, -5 (Gnd).

From these pins, power is supplied via jumpers on the board to the level shifter and to rp2040.

[TechsavvyCNC]

So I should connect the pi to the pi zero like this image. Also wire the SN74AHCT125N like the picture?

[AstaRom]

[TechsavvyCNC]

[

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[TechsavvyCNC]

Is esp32 or rp2040 better?

[AstaRom]

Both options have the right to life. Esp32 can be used with WLED; rp2040 can be selected only for a wired connection, the board is more compact.

[TechsavvyCNC]

So I should wire my esp32 like this picture?

I don't need to plug it into usb and I shoud use firmware hypserspi right?

[AstaRom]

Esp32 needs to be powered from USB.
The above example is for the RP2040-Zero board.

[TechsavvyCNC]

The image above of the esp32 is right? Use io 18,19, 23 and 5. Also use USB to power it.

[AstaRom]

Yes, the connection diagram above is correct

[AstaRom]

19 pin is not necessary to connect now.