ESP32 + PCA9635 Flash at boot

[jonascant]

Hi, is it possible to avoid the brief flash at Boot? Perhaps utilizing the OE Pin? Thanks!

[RobTillaart]

Can you explain a bit more?

[jonascant]

Sorry, Whenever i connect power to the SOC, all channels on the PCA9635 seem to be at the maximum output value, causing a flash on the connected LEDs. When my arduino sketch has loaded, everything is like it should be. Just this brief flash at boot time causes me trouble.

I experienced this with the ESP32 (lolin d32 pro) and ESP8266 (wemos d1 mini).

[RobTillaart]

I have to look into this, might take a few days. has been quite some time that I worked actually with the library.

[jonascant]

Thank you. This is one of the circuits i am using:

[jonascant]

R2 and R3 are not connected. This is to be able to use two transistors without the PCA chip if needed.

[RobTillaart]

From datasheet

So it will cost an IO pin + pull up resistor 1 - 10 K or so to be sure OE is HIGH at startup.

[RobTillaart]

I'm thinking of this interface

1. there should be a function to define the OE pin setOutputEnablePin(uint8_t pin)
2. there should be a function to set OE pin HIGH setOutputEnable(uint8_t value) LOW HIGH
3. there should be a function to set OE pin LOW. setOutputEnable(uint8_t value) LOW HIGH

The latter could also be 2 functions, but as it is expected not being used often, a single one saves some RAM.

Does this meet your needs?

I will prepare a develop branch for it as I think it is a nice feature.

[RobTillaart]

Created a develop branch https://github.com/RobTillaart/PCA9635/tree/develop

Three functions

• bool setOutputEnablePin(uint8_t pin = 255) sets the IO pin to connect to the OE pin of the PCA9635. A value of 255 indicates no pin set/selected. Returns true on success.
• bool enableOutput(uint8_t value) Sets the OE pin HIGH or LOW. All non zero values are HIGH. Returns true on success.
• uint8_t getOutputEnable() get the current value of the OE pin. If pin is not set/selected it will return LOW.

Give it a try

[RobTillaart]

@jonascant Did you have time to try the develop branch?

[jonascant]

Thank you! I didn't get around to it yet, but I will until tomorrow night!

[RobTillaart]

@jonascant Any progress?

[RobTillaart]

@jonascant Any progress?

[jonascant]

Truly sorry, my life got a little crazy. I will test it. Thanks so much! Jonas

Am 20. Februar 2023 17:32:34 MEZ schrieb Rob Tillaart @.***>:

@jonascant Any progress?

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[RobTillaart]

Don't feel pushed, it was silent for quite some time so I was wondering.

[RobTillaart]

@jonascant Any progress?

[RobTillaart]

@jonascant I decided to merge the PR

• code is pretty straightforward
• I did not find problems
• the issue is open for more than a month

If you have test results later I am happy to hear your experiences.

[jonascant]

Thank you, I will let you know! Thanks again!

Am 7. März 2023 16:16:19 MEZ schrieb Rob Tillaart @.***>:

@jonascant I decided to merge the PR

• code is pretty straightforward
• I did not find problems
• the issue is open for more than a month

If you have test results later I am happy to hear your experiences.

-- Reply to this email directly or view it on GitHub: https://github.com/RobTillaart/PCA9635/issues/20#issuecomment-1458348378 You are receiving this because you were mentioned.

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