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[Somewhat solved] NES outputs 4.6V on controller port instead of 5V which prevents Blueretro from functioning properly in c/[email protected]

[–] [email protected] 1 points 5 months ago (2 children)

Only Blueretro is affected. Maybe the Blueretro NES adapter cable has just poor quality components. The other cable adapters I have for other consoles work fine, including the SNES which also operates in 5V.

[Somewhat solved] NES outputs 4.6V on controller port instead of 5V which prevents Blueretro from functioning properly in c/[email protected]

[–] [email protected] 2 points 5 months ago* (last edited 5 months ago) (4 children)

It should be possible to power the BlueRetro using the controller port only. IIRC, the controller pins providing power are directly connected to the internal NES regulator, so with enough headroom to spare, you should be good to go. Eventually, this will depend on the firmware of the ESP-WROOM module used by the BlueRetro (max. current draw for the ESP32 should be around 250mA with all peripherals enabled and transmitting, I’d expect the BlueRetro to use quite a bit less in normal operation). That’s also what the 8BitDo is doing, running at around 100mA.

That’s what I thought too. I originally ordered 4 cables (NES, SNES, N64 & GC). I only had troubles with the NES so I decided to just get a replacement. But the replacement has the exact same behaviour, so this is either an issue with my NES or the cable is not designed properly for PAL NES.

Where did you get the level shifter cable from?

What do you mean by that? The cable itself? It’s from Aliexpress.

I’d also like to know the results of your voltage measurement in operation

As stated below:

4.8V on the controller port itself
4.6V inside the cable adapter without Blueretro Core attached
3.9V inside the cable adapter with Blueretro Core attached
3.53V on input, 2.61V on the output of the AMS1117 when powered by the console only (and the Core itself is not functional that way)

If push comes to shove and you decide to replace the LDO, the TLV1117LV made by TI would be a potential candidate, should be a drop-in replacement with better specs (price is about $0.30)

Will it change something when the input power is so low? I feel like I might as well connect the 5V rail directly to the 3.3V input on the Blueretro…

[Somewhat solved] NES outputs 4.6V on controller port instead of 5V which prevents Blueretro from functioning properly in c/[email protected]

[–] [email protected] 1 points 5 months ago* (last edited 5 months ago) (1 children)

What’s is the voltage you measure on the AMS1117?

3.53V on input, 2.61V on the output.

Does the voltage you measure change when you connect via Bluetooth?

I can’t even connect via Bluetooth. The adapter is effectively not functioning at all: the green power LED indicator is functional but you can’t connect anything to it.

Do your measurements change when USB powered?

Measurements are 4.54V on input of the AMS1117 when powered through USB, output is 3.35V (which seems « normal »).

Does the 4.6V output from the controller drop when you connect over Bluetooth?

As stated before can’t even connect through Bluetooth.

Are you measuring the ports when something is connected or when the ports are open?

The 4.8V measured on the controller port are when nothing is connected.

Does your blueretro work on the ports of the other NES devices?

I unfortunately can’t test the other NES as I don’t have access to them. But I tested the same Blueretro Core on SNES, N64 & GameCube without any issues. From what I got, the SNES, N64 & GameCube controller ports are outputing 3.3V directly, not 5V.

[Somewhat solved] NES outputs 4.6V on controller port instead of 5V which prevents Blueretro from functioning properly in c/[email protected]

[–] [email protected] 2 points 5 months ago* (last edited 5 months ago)

The 74AHCT125N appears to be a 3v to 5v level shifter

I don’t think the cable adapter is using this particular chip. I see two much smaller ones. Maybe that’s the issue.

To be abundantly clear, is the Blueretro meant to work when only powered by the console? It certainly wouldn’t be as convenient – an extra cable and power block to deal with – but everything is functional when externally powered by USB, yes?

That’s right Blueretro is supposed to be powered by the console alone. When powerd by USB, it is perfectly functional.

Do I understand that your original post is debugging why the console isn’t sufficient to power the Blueretro?

That’s correct.

[Somewhat solved] NES outputs 4.6V on controller port instead of 5V which prevents Blueretro from functioning properly in c/[email protected]

[–] [email protected] 3 points 5 months ago* (last edited 5 months ago) (2 children)

What I’ve measured so far:

from the controller port directly: 4.8V
from the wires inside the adapter without Blueretro attached: 4.6V
from the wires inside the adapter with Blueretro attached: 3.9V

There are some active components inside the adapter itself, I guess this could explain the drop 0.2V drop.

So is it sagging?

[Somewhat solved] NES outputs 4.6V on controller port instead of 5V which prevents Blueretro from functioning properly in c/[email protected]

[–] [email protected] 2 points 5 months ago

I can respond to at least your second question right now: I can power the Blueretro from USB while on the console that's how I know it is functioning properly when powered properly (my original post wasn't clear enough I guess).

I'll test the voltage while powered on as soon as I can.