lib works when esp8266 is connected via ftdi cable. fails when using 5v into the V+ pin

[geetee24]

no idea why this bug.

Any ideas? The code fails to set and get register values correctly.

[tttttx2]

That sounds like it could be an electrical issue. Can you make sure you have hooked up gnd and 5V of the VGA connector to the esp as well?

Not quite sure what exact board you have, but maybe the 5V pin of the VGA connector is connected to the ftdi 5V pin directly, but the Vin port runs over a voltage regulator, which only provides 3.3V to the esp and thus does not provide the 5V output to the VGA pin the way you hooked it up? (So 5V is on Vin but not on any 5V ports that you use of the board)

[geetee24]

adafruit huzzah breakbout. unit is all wired perfectly 5v etc.....

[tttttx2]

Ok, then try supplying 3.3V to the VGA 5V instead. Usually it's TTL, maybe the 5V source you use now is slightly higher and thus shifts the HIGH voltage range slightly above what the GPIO pins can provide, compared to the ftdi chip.

Essentially it's just I2C communication, and depends a bit on the display implementation if it works with 3.3V.

[geetee24]

I found that all three of my wall warts power supplies were providing 4.95 V. And we’re causing a problem. Yet if I used simply power from the USB port, which was precisely 5.0 V the problem goes away. Have you ever heard of such a thing?

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On Fri, Apr 5, 2024 at 11:08 PM tttttx2 ***@***.***> wrote: Ok, then try supplying 3.3V to the VGA 5V instead. Usually it's TTL, maybe the 5V source you use now is slightly higher and thus shifts the HIGH voltage range slightly above what the GPIO pins can provide, compared to the ftdi chip. Essentially it's just I2C communication, and depends a bit on the display implementation if it works with 3.3V. — Reply to this email directly, view it on GitHub <#5 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABS6UT3YENEBXJA623LGWV3Y36GPBAVCNFSM6AAAAABFZYEU2KVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDANBQHE4DIMJUGU> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[tttttx2]

Nice.

I guess the following could be your issue:

For 5V TTL you have a voltage range being considered as LOW (e.g. 0-1V) and another one being considered as HIGH (e.g. 4-5V). Those levels heavily depend on the device you're trying to communicate with, as well as if your 5V is actually 5V or a bit different (as that might shift those levels)

If you then try to use a 3.3V output of the esp8266, you might fall in the high range for a high output, if you're unlucky you don't - and thus can't communicate with the device at all, or only with errors.

That's also where my suggestion of using 3.3V instead of 5V on the VGA pin comes from, as this might set your voltage range to 3.3V (and thus accept 3.3V high signals) for the communication instead of the 5V, if you're lucky and the display accepts this.

The proper thing would be to use a level shifter in between, or 5V GPIO capable microcontrollers ;)